Abstract

IJNM

Indian Journal of Nuclear Medicine

0972-3919

Society of Nuclear Medicine, India

ijnm-20-4-poster002

Poster 2

122004

204121131

ijnm-20-4-poster002-001

Evaluation of Carbohydrate Coated Poly (propylene) Imine Dendrimers as Potential Drug Delivery Carrier(s): Pharmacoscintigraphic Studies with Tc-99m Labelled Systems

Babbar

Anil Kumar

¹Agashe

Hrushikesh B.

²Jain

Narendra Kumar

²Jain

Sanyog

¹Sharma

Rakesh Kumar

¹Division of Radiopharmaceuticals, Nano Tech and Stem Cell Research, INMAS, Brig. S. K. Mazumdar Road, Delhi 110054²Dept. of Pharmaceutical Sciences, Dr. Hari Singh Gour University, Sagar (M.P.)

Abstract

The aim of the present work was to study the biodistribution of fifth generation of poly (propylene) imine dendrimers (PPI-5.0G) and carbohydrate (mannose and lactose) coated dendrimers (M-PPI and L-PPI, respectively) in mice in order to explore the potential of carbohydrate coated dendrimers as carrier system for drug delivery. Plain PPI dendrimers were synthesized and were coated with sugars following the established procedures reported in the literature. All the three systems were labeled with technetium-99m. Percent labeling efficiency, in vitro and in vivo stability of the complexes was evaluated. The blood clearance study was performed in female New Zealand rabbits. The biodistribution profile of the dendritic carriers was investigated in female Balb/c mice. The dendritic formulations were labeled with 95% labeling efficiency. The labeled complexes were found to be stable in vitro (97-98 % stability) and in vivo (89-94 % stability). All the formulations were cleared rapidly from circulation; clearance of M-PPI and L-PPI was faster than PPI-5.0G. All the formulations were accumulated in liver to a significant extent but only those with terminal carbohaydrate moieties were retained for longer period. Maximal accumulation of PPI-5.0G and L-PPI was observed in kidneys whereas in case of L-PPI only little activity was detected in kidneys. Rapid clearance of the dendrimers was in accordance with the earlier reports. Higher and longer retention of M-PPI and L-PPI in liver was attributed to lectin-carbohydrate interactions. Lesser accumulation of L-PPI in kidneys was indication of its lesser excretion. This observation can be explained based on molecular weight of L-PPI, which is greater than threshold of glomerular excretion. In general, it was observed that the carbohydrate coated dendrimers get distributed in liver to a significant extent and play a vital role in drug targeting to liver.

ijnm-20-4-poster002-002

Alternative Approach to Dedicated Workstations in Gamma Camera SPECT Systems for Image Processing in Nuclear Medicine

Baghel

Radiation Medicine Centre (BARC), Tata Memorial Centre, Annexe, Parel, Mumbai-400 012

Abstract

In Nuclear Medicine departments, scintillation Gamma Camera SPECT systems are used extensively to carry out diagnostic studies using radioisotopes. These dedicated systems are equipped with dedicated computer systems and most of them have UNIX operating systems with X-windows as graphics user interface (GUI). In a busy nuclear medicine department, there is always need for more than one workstation to work smoothly. In a system, acquisition workstation (AWS) is directly connected to gamma camera for data collection using high-speed communication and analysis workstation(s) are connected to AWS by standard local area network using TCP/IP protocol. These workstations have dedicated hardware with analysis and display software, which are very expensive. The Personal Computers (PCs) can be used as workstations in addition to their stand-alone utilities for this purpose. We have dual head gamma camera SPECT system (Picker AXIS), interfaced with Odyssey FX computer system having UNIX operating system Version 4.0 and X-windows and this system is connected to RMC local area network. We have configured UNIX-based dedicated systems to PC using “WinAxe” X-windows emulation software. All the systems are configured for TCP/IP communication protocol and emulation software is configured with AWS. This emulation software can be installed to any number of PCs to use as workstation, depending on the user license. All the functions of workstations like reconstruction, processing, display and printing can be carried out on these PCs. The software eliminates the requirement of expensive workstations and in addition to it, the doctors can process and report nuclear medicine studies on their PC desktop without going to the gamma camera room. The data displayed on these systems can be captured and stored in graphics format and hard copy can be taken on network laser printer. The major advantage is the number of processing workstations can be increased cost effectively and any PCs can be used as a workstation in addition to its general-purpose use.

ijnm-20-4-poster002-003

Studies on the Feasibility of Using Titanium Polymer as a Potential Adsorbent for Low Specific Activity 99Mo for the Preparation of ⁹⁹Mo-^99mTc Generators

Sarkar

²Nandy

¹Dash

¹Laxminarayan

¹Ram

Ramu

¹Gandhi

¹Pillai

MRA

³Ramamoorthy

³Meera

^1,²

¹Radiochemistry & Isotope Group, BARC, Mumbai - 400 705²Board of Radiation and Isotope Technology (BRIT), BARC, Mumbai - 400 705³International Atomic Energy Agency, A1400, Vienna, Austria

Abstract

Preparation of a zirconium based polymer, poly zirconium compound (PZC), which has higher adsorption capacity (200mg Mo/g of PZC) for low specific activity reactor produced (n,g) ⁹⁹Mo, for preparation of column generators was reported by Japanese scientists [1]. As an off-shoot of the reported developmental work on PZC [1], a titanium based polymer is prepared and evaluated in our present study. A titanium (IV) polymer (TP) was synthesized by reacting titanium (IV) chloride and isopropyl alcohol. The adsorption characteristics of Mo on TP were studied with inactive Mo spiked with tracer quantities of ⁹9Mo and adsorption capacity under dynamic conditions was found to be ~35mg Mo per gram of TP. ⁹9Mo-^99mTc generators containing upto 11.1GBq (300mCi) ⁹9Mo adsorbed on 5.5g of TP column (40x13mm) were prepared and performance was evaluated in terms of ease of elution of ^99mTc, percentage elution yield of ^99mTc, percentage 9⁹Mo break-through, pH of eluate etc. It was seen that about 92% of ^99mTcO₄ available in the generator was eluted within the first 6ml volume of normal saline. Subsequently ^99mTcO₄⁻was eluted in normal saline (6ml) and the mean practical yield of ^99mTc was ~67± 7.8 (n= 10). Although ⁹9Mo breakthrough is higher than the permissible limit of 0.1% at the beginning of the elution of ^99mTc from the generator, it reduced to below permissible limit on subsequent elution of ^99mTc. Use of an alumina column as a purification step would be very effective for reducing ⁹9Mo breakthrough as reported by the Vietnamese group for ⁹9Mo-PZC-alumina based ^99mTc generator [2]. The radiochemical purity of ^99mTcO₄⁻ was >98% while the labeling efficiency of pertechnetate with in-house Tc-cold kit compounds were >95 %.

TP has a modest adsorption capacity for molybdenum in comparison to the conventional adsorbing material, acidic alumina, for making column chromatography generator for ^99mTc. Use of TP as a potential adsorbent for (n,g) ⁹9Mo has been demonstrated for preparation of column type ⁹9Mo - ^99mTc generator system.

Key words⁹⁹Mo - ^99mTc generatorLow specific activity (n.ã) ⁹⁹MoNew adsorbent for MoTitanium Polymer (TP) adsorbent

References1

Masakazu

Katsuyoshi

Koji

Kiyo yuki

Mizuka

Yoshio

Appl. Radiat. Isot, (1997) 38, 5, pp 607.2

Van So

Report of the 1^st Research Coordination Meeting on ‘Development of generator technologies for therapeutic radionuclides’ 2004, IAEA Headquarters, Vienna, Austria. (2004) pp 115-127.

ijnm-20-4-poster002-004

Synthesis and Radiolabeling of -LHI-FA-N4 Peptide for Infection Imaging

Mittal

Gaurav

Chuttani

Krishna

Kumar

Nitin

Sharma

Rakesh K.

Sharma

Rajnish

Mishra*

Anil K.

Institute of Nuclear Medicine and Allied Sciences Brig. S. K. Mazumdar Marg, Delhi-110 054, India

Abstract

Aim of the study was to develop a peptide conjugated with N4 configuration through a lipophilic linker and to label it with different radioisotopes that can specifically discriminate between bacterial and sterile inflammation. For this purpose, we have developed a series of antimicrobial peptides, specific to bacteria and to leukocytes in vitro, which are based on the sequence of honeybee (Apis mellifera) antimicrobial peptide family, Jelleines. In order to label it with 99mTc, the peptide has been conjugated to a N4 configuration on the N-terminal of the peptide, with enhanced lipophilicity with different carbon chains. N4 configuration provides stable chelating moiety to hold the metal ion with very high stability under physiological conditions. Radiolabeling was performed at room temperature using glucoheptonate as a transchelator. Stability studies in saline and serum show that only 0.5% of metal ion was dissociated within a period of 7 hours. Challenge studies with DTPA (1.0mM) and cysteine demonstrate no evidence of transcomplexation of ^99mTc to DTPA and less than 3% of the 99mTc-labeled peptide was transcomplexed to cysteine (1.0mM) after 1hour incubation at 37°C. Biodistribution data of the radiolabeled peptide in 2-3 month old Balb/c mice showed highest uptake in kidneys, liver, intestines and blood. The blood kinetics data in rabbits after intravenously administering 99mTc-labeled peptide exhibited a biphasic blood clearance pattern characterized by a fast half-life i.e., T_1/2(_f) of 17±1.2 min and a slow half-life i.e., T_1/2(s) of 13.7 ± 1.1 h. 99mTc-labeled peptide was injected into mice infected with Staphylococcus aureus (S. aureus) and the amount of radioactivity associated with bacteria and leukocytes was quantitated. Scintigraphy of New Zealand white rabbits infected with S. aureus in the right thigh muscle showed an uptake of 99mTc-labeled peptide up to 24 h post administration. Based on radiochemical studies and animal studies we propose this 99mTc-labeled -LHI-FA-N4-peptide as candidate of preference for detection of bacterial infection in humans.

Key wordsApis melliferaantimicrobial peptides99mTc and infection imaging

References1

Fontana

Mendes

M.A.

de Souza

B.M.

Konno

Cesar

L.M.M.

Malaspina

Palma

M.S.

Peptides, 2004; 25, 919-928.2

Casteels

Ampe

Jacobs

Vaeck

Tempst

EMBO Journal, 1989; 8, 2387-2391.

ijnm-20-4-poster002-005

Novel ^99mTc Radiolabeled Phthalamide Substituted Pyrane Analogue: Synthesis and Biological Studies in Mice

Tiwari

Anjani K

Mishra

Pushpa

Mathur

Rashi

Sharma

R.K.

Mishra

A.K.

Department of Radiopharmaceutical Chemistry, INMAS, Brig. S.K. Majumdar Road, Timarpur Delhi-110054, India

Abstract

The gastrointestinal peptides CCK and gastrin both having similarity at COOH terminal positions along last five amino acids. These two are regulators of different brain neurotransmitters and various activities of gastrointestinal tract. Two different derivative of Phthalamide based Benzopyrane have shown promising result in the imaging of CCK receptors. These two have been synthesized and characterized on the basis of spectroscopic techniques and evaluated radiopharmaceutical potentials. The labeling efficiency was more then 98% and complex was stable for about 8 hours at 30°C and also shown its affinity to most of the organs, known to express CCK receptor.

Three consecutive process in 4-Methyl-7Hydroxy Coumarin and N Methylol Phthalamide having small amount of sulfuric acid with 3 hours refluxing (Product => 4-Methyl-7Hydroxy[ N(-Methyl Phothalamide)] Benzo-[1,2,6]- Pyrazone). The final Pyrane analogue is obtained by treating this product is treated with phenylenediamine in dry Pyridine followed by Benzaldehyde in glacial acetic acid. Labeling efficiencies were found more than 98% for the final; product [4-Styryl, 7Hydroxy - 8(N-Methyl-Phthalamide) quinoline (1,5C) benzamidazole]. Similarly Biodistribution and scintigraphic studies have shown binding of this compound to all CCK receptor organs, which has been further corroborated by scintigraphic studies. In view of this Phathalamide substituted Pyrane analogue is suitable for the imaging of CCK receptors and can be conjugated to wide variety of vector molecules for therapeutic application.

ijnm-20-4-poster002-006

To Assess the Quality of Whole Body 18F-FDG PET/CT Scan after Varying the Acquisition Parameter of CT Scan

Shetye

S Bhakti

Rangrajan

Samuel

Department of BIO-IMAGING Unit, Tata Memorial Hospital, Parel, Mumbai-12

AbstractMethods

10 patients were selected randomly for this study. Whole body 18F-FDG PET/CT scan was performed by intravenous administration of ~10 mci of 18F-FDG. Oral contrast was given to all patients. With proper instructions patients were asked to wait in a separate room. After 45 minutes of waiting period they underwent the whole body scan.

The topograph was taken to decide the scan length of the patient. CT scan of selected range was done to calculate the attenuation correction factor. In routine PET/CT study CT was done using 140 kev X-rays and 110 mAs. CT done using 120 kev X-rays and 60 mAs is called as low dose PET/CT study. Both the studies were evaluated by trained nuclear medicine person and radiologist.

Results

SUV values based on patient's bodyweight were used for the interpretation of the lesions. Lesion showing SUV value above 2.5 is considered as positive site. Total 71 lesions were detected on routine PET/CT study. Out of 71,68 lesions were detected on low dose PET/CT study. Out of these 3 lesions not seen on low dose PET/CT study, two were borderline positive (SUV=2.5), 1 was present in the bone. No change in the sharpness and size of the lesions was observed in both studies. Soft tissue lesions showed higher SUV values than routine PET/CT study but the bony lesions showed lower SUV values than routine study. No significant change in size of the lesion is noted on both the scans.

No significant change was noted in the delineation of lesions in both studies. Lesions seen on routine CT (140 kev) were also seen on low dose CT (120 kev) but scan appeared more grainy using 120 kev X-rays.

CT dose index (CTDI) using 140 kev X-rays and 110 mAs was 7.30 mGy and using 120 kev X-rays and 60 mAs was 2.87 mGy.

Conclusion

In our study we observed that 95% of the lesions got detected on low dose PET/CT scans. A significant difference is observed in a radiation burden delivered to a patient by using routine PET/CT protocol and low dose PET/CT protocol. Hence by using low dose PET/CT protocol for whole body scan would give additional benefit of low radiation dose without compromising the quality of whole body PET/CT scan.

ijnm-20-4-poster002-007

Ectopic Gastric Mucosa

Gupta

Agarwal

Kumari

AzeezAtulya

Kumar

Shah

Dept Of Nuclear Medicine, Manipal, Karnataka, India

Abstract

A 12 year old male presented to the department with a history of bleeding per rectum.

Per rectum examination revealed staining of glove with fresh blood. Rectum was empty and dilated. Blood parameters were within normal limits.

Colonoscopy did not find any bleeding in the ileo-caecal junction. Tc-99m Pertecnetate scan showed an abnormal focus of radiotracer concentration in the left ileo-ceacal fossa with no evidence of further movement-suggestive of ectopic gastric mucosa in Meckel's diverticulum.

Exploratory laparotomy showed the presence of ? Meckel's diverticulum at about 3 feet from the ileo-caecal junction. Resection and anastomosis were done. Histopathology report confirmed it to be Meckel's diverticulum with heterotopic pancreatic tissue.

Key wordsEctopic gastric mucosableeding per rectumMeckel's Diverticulumheterotopic pancreatic tissueTc-99m Pertecnetate scan

References1

Kumar

Tripathi

Chandrashekhar

Agarwala

Kumar

Dasan

J.B.

Malhotra

“Diagnosis of ectopic gastric mucosa using Tc-99m-pertecnetate-Spectrum of scintigraphic findings.”

Br. J. Radiol: 2005 Aug; 78(932): 714-20.2

Emanian

S.A.

Shalaby-Rana

Majd

“The spectrum of heterotopic gastric mucosa in children detected by using Tc-99m-pertecnetate scintigraphy”

Clin. Nuc. Med., 2001 Jun; 26(6): 529-35: Review

ijnm-20-4-poster002-008

Empirical Analysis and Enumeration of Causes for Variable Yields in Production of F¹⁸-FDG

Naresh

AnjaneyuluPhaniraju

Gada

Atul

Vipin

Prasanna

Apollo Gleneagles PET-CTCentre, Hyderabad, Andhrapradesh, India

AbstractBackground

After unloading F¹⁸ from cyclotron target, an automated chemistry unit Explora FDG-4 converts F¹⁸ by nucleophilic substitution reaction into F¹⁸ FDG, used for PET imaging. Explora deploys predefined recipes, which were executed to initiate proceedings for cleaning, testing and synthesis as per manufacturers specifications. The entire operation was continuously monitored for temperature, pressure, radiation changes, control set points and sensor feedback.

Objective

To critically assess various causes for yield variations during production of F¹⁸-FDG using Siemens-CTI FDG-4 Explora chemistry synthesis unit, our initial experience with an aim towards optimization of FDG production.

Materials and Methods

In our seven months experience FDG yield dipped very low at times and on few occasions there was no activity at all. We analyzed various problems, we encountered and stratified them under different categories with an intention to deal with them effectively. These are 1. Regulation factors. 2. Reagent related problems and 3. Maintenance and upkeep related issues.

Conclusion

Explora FDG4 unit has efficiently automated complex chemical reactions and simplified reaction monitoring; still there are some issues that can cause variations in the FDG output.

Apart from instrument factors, variation in the production yields were attributed to

Critical placement of peek-tube-dip line inside reaction vessel.

Unwarranted leaks, despite successful self-test.

Deranged function of purification cascade assembly-not a part of initial self-test check.

De-ranged trapping mechanism.

Maintenance and upkeep of equipment.

Key wordsF¹⁸-FDGExploraSynthesis

ijnm-20-4-poster002-009

Biological Effects of Depleted Uranium

Omar

Ha-Redeye

McMaster University, Hamilton, Canada

AbstractPurpose

Though a great body of information exists concerning Depleted Uranium (DU), there remains significant debate about its potential health effects. Most of the information available discounting the likelihood of any significant effects resulting in the use of DU in a wartime setting is based on human epidemiological studies of uranium millers/miners and workers in nuclear weapons and fuel workers between 1940-1970. However, a newer body of literature has been developed positively demonstrating the adverse effects of DU from the chromosomal level to fetal development in in-vivo and in-vitro studies. Techniques currently exist to estimate the levels of DU in both the environment and the patient. Though urine samples have traditionally been used, they may prove inaccurate as DU stores in long-term deposits in the bones. Since the detrimental effects of DU in the bones has now been well established, the use of gamma scintillation bone scans may prove most effective in identifying early bone lesions. Treatment and suppression for patients suspected of DU exposure is also rapidly developing. The means to identify, estimate, and respond to such incidents is becoming increasingly important as the proliferation of DU weapons expands beyond Western nations.

Objectives

To compare the various means of DU detection and determine the effectiveness of ë scintillation in detecting early bone lesions

To verify the biological effects of DU in human subjects

To evaluate the usefulness of various therapies proposed by literature

MethodsInstrumentation

Urine samples

HpGe solid state detectors

Overly sensitive NaI ë detectors with thick crystals

Rapid detection of fragments or shards with ë-ray spectrometry

Oak bark, sapwood sampling

Therapy

ë scintillation detection of osseous metastases

Phenyl Acetate (Phenyl Fatty Acid) chemoprevention through p21RAS protein pathway

Chelating agents; Cu, Fe, Mn, Zn, EHBP, Tiron, DTPA

Fauna uptake suppression with Ca²⁺ competitive depression

Results

The study was interrupted by the pending conflict in Iraq, which precludes the direct, continued, and uninterrupted access to civilian populations in southern Iraq. The continued conflict introduces additional DU materials, complicating estimations of DU toxicity.

Conclusions

Reports dismissing the adverse effects of DU are based on erroneous assumptions and older literature. Substantial evidence currently support concerns over DU toxicity and their use in military settings. These concerns necessitate longitudinal studies that can conclusively determine their epidemiological effects in human populations when political circumstances allow it.

Key wordsDepleted UraniumIraqcivilian populationstoxicity

ijnm-20-4-poster002-010

Sentinel Lymph Node Scintigraphy & Gamma Probing in Patients With N₀ Head & Neck Cancers - Our Initial Experience

Sundaram

¹Padma

¹Kuriakose

²Iyer

²Kumar

¹Dept. of Nuclear Medicine, Amrita Institute of Medical Sciences, Cochin-26, Kerala²Dept. of Head & Neck surgery, Amrita Institute of Medical Sciences, Cochin-26, Kerala

Abstract

The single most important factor that predicts patient outcome in Head & Neck Squamous cell Carcinoma (HNSCa) is lymph node metastasis status. Reported incidence of occult metastasis is about 30%. Standard treatment offered to these patients is neck dissection. This approach, although beneficial for 30% of patients with metastasis, is an over treatment in 70% pts without metastasis. In our ongoing prospective study, we attempted to develop a minimally invasive approach to evaluate nodal metastasis so that treatment can be directed based on actual stage of disease.

Aim

To assess feasibility & standardize Sentinel Lymphnode Scintigraphy (SLS) in HNSCa pts.

To compare SLS to current gold standard elective neck dissection.

To determine whether SLS can replace elective neck dissection as a diagnostic tool.

Materials and Methods

51 Patients (M:F = 39:12, Mean age: 48+5 yrs) with a clinical staging of N₀ were selected for SLS (9/03 to 3/05). SLS was performed on the day of surgery. 3-4 injections of 0.1 ml each (total < 37MBq) of ^99mTc labeled filtered sulfur colloid were given peritumourally. Imaging performed using a dual head gamma camera & skin markings of sentinel node done. Then intra operative sentinel node probing was preformed using a cordless gamma probe (Gamma Finder, Germany).

Patients were assigned to two groups GpA & GpB 23: 28 pts (A-would undergo Sentinel Node (SN) sampling & neck dissection if SN is positive for metastases by frozen section & B-would undergo SN sampling & neck dissection irrespective of the frozen section result). All had a close follow up for lymph node recurrence.

Results

Most of patient's primary were in oral cavity (tongue: buccal mucosa: floor of mouth = 42:5:4). Primary tumours were staged clinically as T_I: T₂: T₃ = 22:26:3 pts but nodal wise all N₀. SNS & probing was successful in all pts except for one (98%). Frozen section showed 8/51 (16%) SN to be positive for occult metastases. (GpA 2 & GpB 6pts). Only 1/23 pts was found to have lymph node metastasis in GpA & GpB showed no metastasis during 6 months median follow-up period.

Conclusion

This study shows that a standardized SLS is technically feasible & an equally sensitive modality in occult lymph nodal metastasis detection when compared to elective neck dissection. It is possible to obviate neck dissection in N₀ HNSCa pts based on SLS findings.

Key wordsHeadNeck cancersSentinel nodescintigraphy & Gamma probe

ijnm-20-4-poster002-011

Artifacts in Whole Body PET-CT Imaging

Rajai

Prathamesh R.

Tikoo

Sangitaa B.

P. D. Hinduja National Hospital & MRC, Mumbai, India

AbstractBackground

Fluro dioxy glucose positron emitting tomography (¹⁸FDG PET) Imaging is a sensitive technique in the detection of disease in the early metabolic phase. However the specificity is low. One of the reasons for the low specificity is due to Artifacts which mimics the disease.

Method and Results

We retrospectively analysed Whole Body FDG PET images performed during July 2003 - July 2005 for evidence of different types of Artifacts which produce difficulties in interpretation. We encountered the following types of artifacts:

Truncation Artifacts - 1

Brown Fat Artifacts - 6

Bowel Artifacts (Hot) - 3

Bowel Artifacts (Cold)-3

Ureteric Artifacts - 2

Diaphragmetric Artifacts - 1

Stomach Artifacts (Cold) - 2

GE Junction Artifacts (Hot) - 1

Conclusion

We conclude that the knowledge of different types of artifacts in PET-CT imaging should be kept in mind while interpretation of PET images to improve the disease specificity.

ijnm-20-4-poster002-012

Radiation Exposure to Staff Working in PET Facility

Rajashekharrao

Kumar

Hemant

Kamaldeep

Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Centre Annexe Parel, Mumbai - 400 012

Abstract

In India, the use of PET as an imaging modality is growing rapidly since last 2 years. With the advent of PET, several new occupational radiation safety problems have arisen, mainly concerning radiation exposure of PET personnel. The penetrating ability of the high-energy 511 keV g-radiation produced due to the annihilation reaction of positron and negatron is greater than that of 140 keV g emissions from routinely used ^99mTc-labeled radiopharmaceuticals. The specific gamma ray dose constant of 511 keV photons (5.7 R/h/mCi @ 1cm) is almost 7 times higher than that of 140 keV photon (0.8 R/h/mCi @ 1cm). Also, the thickness of lead material required for effective shielding of 511 keV g-rays (HVT=4.0 mm) is much higher than that for 140 keV photons (HVT=0.3 mm) used in conventional diagnostic nuclear medicine. The introduction of PET has therefore given rise to concerns of radiation exposure, especially to staff working in PET facility.

At Radiation Medicine Centre, PET studies are routinely carried out using ¹⁸FDG. The staff working in a PET facility mainly receives exposure from routine work practices like receiving and opening the ¹⁸FDG consignment, dispensing and measurement of radioactivity, dose administration, patient positioning and imaging. We have evaluated the occupational radiation exposure to staff working in our dedicated PET facility using Direct Reading Dosimeters (DRD) and Thermoluminescent Dosimeters (TLD).

The whole body radiation doses to the PET staff per study recorded using DRD ranged from 3.3 mSv to 8.8 mSv with a mean of 5.4±2.0 mSv. From the chest TLD report, the whole body doses per study was calculated and it ranged from 3.9 mSv to16.0 mSv with a mean of 9.6±2.1 mSv. The doses recorded using DRD was found to be lower by a factor of 2 as compared to that using TLD. Considering the fact that the measurements using TLD are more accurate and with an average exposure of almost 10 mSv/study, a single staff performing all the duties in a PET facility and performing 8 studies a day would receive an annual effective dose of almost 20mSv.

Although principles of time, distance and shielding are always practiced for any procedure involving radioactivity administration, particular care needs to be taken to enforce these when working in PET. At our Centre, the policy of rotation duties combined with safe work practices has enabled us to keep the doses to staff working in PET well below the average annual effective dose limits of 20 mS v.

Key wordsRadiation dosesPET¹⁸FDGDRDTLD

ijnm-20-4-poster002-013

Radiation Doses to Comforters From Non-ambulatory and Pediatric Patients Administered Therapeutic Activity of Radioiodine

Rajashekharrao

Kamaldeep

Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Centre Annexe, Parel, Mumbai-400 012

Abstract

Radiation Medicine Centre (RMC) is the largest referral Centre in India for the treatment of patients with differentiated thyroid cancer (DTC) and neural crest tumors (NCT). The therapeutic activity administered for DTC generally ranges from 30-250 mCi of Na1³1I and that for NCT ranges from 50-200 mCi of ¹³¹I-mIBG. These patients after treatment are hospitalized in an isolation room and discharged from the hospital when the whole body ¹³¹I activity retained is less than or equal to 15 mCi, corresponding to an exposure-rate of 3 mR/h or less at 1-metre distance. Patients who are ambulatory and in the adult age group, during their stay inside the isolation room are able to manage and take care of their own routine needs. However, non-ambulatory and pediatric patients are dependent on their family members for their daily care and needs.

During the period 2000-2004,45 non-ambulatory patients of DTC, 6 pediatric patients of DTC and 16 pediatric patients of NCT underwent treatment at RMC. The amount of therapeutic Na¹³¹I activity administered for DTC patients ranged from 37.7 mCi to 265 mCi and that of ¹³¹I-mIBG ranged from 58.8 mCi to 128.7 mCi. The comforters who knowingly and willingly agreed to provide care, comfort and support to the patient after treatment, were given all necessary instructions regarding radiation safety and hygiene practices so as to keep the radiation exposure As Low As Reasonably Achievable (ALARA). Protective clothing, gloves, gum-boots etc. were provided to the comforters while attending to the patient. In order to avoid any accidental uptake of ¹³¹I by the thyroid gland due to contamination, the comforters were administered stable iodide as a blocking agent. Personnel monitoring of these comforters were carried out using Thermoluminescent Dosimeter (TLD. The comforters were routinely monitored to check for any contamination.

In patients with DTC, the radiation doses to the comforters ranged from 0 mSv to 4.95 mSv with a mean±SD of 1.00±1.12 mS v and a median of 0.58 mSv. In patients with NCT, it ranged from 0 mSv to 30.30 mSv with a mean±SD of 7.73±9.92 mSv and a median of 2.08 mSv. The comforters attending to NCT patients received higher doses as most of the patients were in the pediatric age group (2-7 years) and the comforters therefore were in close proximity to the patient for prolonged time period.

The radiation safety surveillance during treatment of non-ambulatory and pediatric patients has enabled us to keep the effective dose to the comforters ALARA.

Key wordsComfortersEffective DosesTherapy¹³¹I¹³¹I-mIBG

ijnm-20-4-poster002-014

Comparison of Tc-99m Perfusion Scintigraphy and Color Doppler Sonography in Diagnosis of Patients with Cold Thyroid Nodules

Sharma

Rajnish

¹Saha

Kanta

¹Chakraborty

K.L.

²Mondal

Anupam

¹Sawroop

¹Rawat

H.S.

¹Sahoo

³Mishra

Anil

¹Kashyap

Ravi

¹Department of Nuclear Medicine, INMAS, Delhi-110054²Department of Radiology, INMAS, Delhi-110054³Department of Cytopathology, INMAS, Delhi-110054

Abstract

We prospectively studied 24 patients with cold thyroid nodules (four malignant and 20 benign nodules) on Tc-99m pertechnetate scintigraphy to investigate the diagnostic value of Tc-99m perfusion scintigraphy and color-doppler sonography in differentiating malignant from benign thyroid nodules. This was followed by an FNAC test at an interval of one week for all the subjects. The patient found to harbor malignancy or an indecisive FNAC reports were subjected to surgery. In each patient, Tc-99m perfusion uptake in the nodule was assessed. Both the uptake and vascularity were classified as low, Iso or high. Five out of 24 nodules showed high Tc-99m perfusion uptake; four of them were malignant. Eight (including four malignant tumors) out of 24 nodules showed increased vascularity compared with normal thyroid tissue on color-Doppler sonography. 1 patient who had a cytopathology report of hyperplastic goiter was found to have high vascularity both on radionuclide scintigraphy and Doppler study. Histopathology done later reported a follicular adenoma. The sensitivity, specificity and positive predictive value of Tc-99m perfusion scintigraphy and color-Doppler sonography were determined to be 80% and 95.2% and 80% for radionuclide perfusion study and 80% and 78.9%, and 50% for color Doppler study respectively. We conclude that Tc-99m perfusion scintigraphy and color-Doppler sonography appear to have similar sensitivity in the detection of malignant thyroid nodules. However color Doppler had a lower specificity and positive predictive value in the diagnosis of malignant nodules. Color Doppler has variable presentations in thyroid nodules. Partial peripheral or central vascularity has been found in benign thyroid nodules.

This may be responsible for lower specificity and positive predictive value of the Doppler study.

Key wordsSolitary thyroid NoduleColor Doppler studyRadionuclide perfusion studies

ijnm-20-4-poster002-015

Quality Assurance and Performance Evaluation of First PET/CTin India USINGNEMANU2-2001 AND AAPMTG36

Rameshwar

¹Dayananda

²Rangarajan

¹Samuel

¹Bio-Imaging unit, Tata Memorial Hospital, Parel, Mumbai-12²Departments of Medical Physics, Tata Memorial Hospital, Parel, Mumbai-12

AbstractAim

To evaluate the performance characteristics of the PET/CT in 2D and 3D mode for whole body scanning, using NEMA-01 and multisliceCT using AAPMTG 36.

Materials and Methods

The PET/CT scanner -GE Discovery ST consists of one integrated gantry containing a) slip ring design CT X-ray tube and Hi-light matrix II detector assembly consisting of 21,888 individual elements b) 24 PET detector rings comprising 12,096 (BGO) crystals each of 6.3 × 6.3 × 30 mm³ and Lower and upper energy were 375 and 650 keV, with 11.7 ns coincidence window. CT acquires a maximum of 16 slices with minimum slice thickness of 0.625 mm in one tube rotation at a scan speed of 0.5 seconds.

Calibrations (detector sensitivity and electronic characterizations such as adjustment of PMTs gain, definition of crystal and energy maps and coincidence timing) were applied, alongwith NEMA-01 tests (resolution, sensitivity, scatter fraction (SF), counting rate performance and NEC) were performed. Whereas for CT, tests were performed to evaluate low and high contrast resolution, image uniformity and noise, CT number accuracy, slice sensitivity profiles and CT dose index CTDI.

ResultPET

The average transaxial and axial spatial resolution (FWHM) at 1 cm and 10 cm off axis was 5.5 (5.3) mm and 6.6 (6.6) mm in 2D, and 5.8 (5.7) mm and 6.7 (6.2) mm in 3D. The average sensitivity (R=0 cm and R= 10 cm) was 2.6 cps/kBq in 2D and 11.8 cps/kBq in 3D. Scatter fraction was 20% in 2D and 46% in 3D. The NEC peak rate was 61.47 kcps at 40.67 kBq/cc in 2D and 45.57 kcps at 16.45 kBq/cc in 3D, when random coincidences were estimated by using k=2 in the NEC formula, while the NEC peak rate was 89.41 kcps at 49 kBq/cc and 60 kcps at 12 kBq/cc in 2D and 3D(using k=1).

Measured sensitivity profile widths were within ± 0.4 mm. Uniformity of mean CT numbers of water (0.53 HU) is in specified limit of 0±2 HU. Image noise is slightly higher (3.98 HU) than manufacturer specified limit of 3.2±0.3 HU. Measured contrast difference between water and plastic, 118.87 HU was within specified limit of 120±12 HU. CTDI on surface (17.37 mGy; head and 10.78 mGy; body) and center (16.51 mGy; head and 5.12 mGy; body) was within specified limit.

Conclusion

PET show excellent system sensitivity with relatively uniform resolution throughout the FOV in both 2D& 3D modes, with the parameters being within acceptable specifications of NEMA NU-2001. Overall performance of the CT scanner is also satisfactory within the limits specified by the manufacturer and AAPM report no 36.

ijnm-20-4-poster002-016

Biological Dosimetry in Patients Receiving Therapeutic Dose of Iodine-131

Senthamizhchelvan

Pant

Bal

Malhotra

lka

Nair

Rath

¹Department of Nuclear Medicine, AIIMS, New Delhi, India²Department of Radiotherapy, AIIMS, New Delhi, India

AbstractObjective

The micronucleus (MN) assay in peripheral blood lymphocytes was used to assess the genotoxic potential of a single dose of iodine-131 (¹³¹I) given to 56 patients for ablation of thyroid remnants after total thyroidectomy.

Methods

Lymphocytes were taken at various times after ¹³¹I therapy (from 2 to 180 days), and evaluated for the presence of MN. Two paired, independent lymphocyte cultures were set up for each blood sample coming from a sub-set of fifty-six patients. 0.5 ml heparinised blood aliquots were cultured in a complete media, consisting of 4.5 ml RPMI-1640 supplemented with 1.5% phytohemoagglutinin (PHA). After 44 h, Cytochalasin B was added to a final concentration of 6mg/ml. Cells were harvested at 72 h, and slides were prepared according to standard procedures. The mitogenic stimulation achieved was sufficient to evaluate the frequency of binucleated lymphocytes with micronuclei (BNMN) in 1000 binucleated cells for each blood sample.

Results

A significantly increased MN frequency was observed in lymphocytes of patients as soon as the first sampling time (2days after ¹³¹I therapy), peaking at day 3 at almost two fold the spontaneous frequency observed in the pre-therapy samples. MN frequency slowly declined thereafter, reaching the baseline levels at the 180-day time point. A significant relationship was found between the MN frequency observed in lymphocytes of patients after ¹³¹I therapy and the genotoxicity.

Conclusion

Increased MN frequency induced by radioiodine therapy has previously been reported for differentiated thyroid cancer (DTC) patients treated with ¹³¹I. The data we obtained, while confirming to some extent the previous findings, indicate nevertheless that the increased level of MN frequency induced by ¹³¹I therapy is still highly significant 60 days after radioiodine treatment, but not at 180 days. Complete disappearance of any incremental effect on MN frequency 180 days after radioiodine therapy suggests either that the damage inducing the abnormally high MN frequency has been recovered or that all damaged cells have selectively been removed within 6 months.

Key wordsDifferentiated thyroid cancerIodine-131 therapyGenotoxicityMicronuclei

ijnm-20-4-poster002-017

Evaluation of Biograph-16 (Siemens) PET-CT High Speed LSO/UFC Detector Generated-Images and Optimizing Imaging Time for Various Protocols Using F18-FDG

Vipin

Reddy

Kavitha

Potharaju

Suryaprakash

Rao

Jyotsna

Gada

Atul

Apollo Gleneagles PET-CT Centre, Apollo Hospital Complex, Jubilee Hills, Hyderabad, AP-500033

AbstractObjective

To standardize acquisition protocols based on assessment of image quality & the effect of variable acquisition time.

Materials and Methods

Randomely selected 25 patients data were analysed by three independent experienced physicians. Followed by CT, PET images were acquired for dual time interval, 45-60 min after injecting (0.15-0.20 mCi/Kg) F-18-FDG.

CT-attenuation corrected, uncorrected PET and PET-CT fused images were displayed after iterative reconstruction for assessment of image quality, in terms of image definition, lesion detection, contrast, resolution and were graded as acceptable/non-acceptable based on adequacy of sampling and without compromising diagnostic confidence.

Conclusion

Based on the above results, the acceptable diagnostic quality average imaging times were standardized and implemented for regular use.

Category	Whole body	Brain	Cardiac

Childrens & thin patients <40Kgs	2-3 min/bed position	5-7 min/bed position	5-7 min
Average built patients 40-70Kgs	3-4 min/bed position	8-10 min/bed position	8-10 min
Above average & Obese patients >70Kgs	5-6 min/bed	10-15 min/bed	10-15 min

Study is ongoing & is amenable to slight modification. Please consider this.

ijnm-20-4-poster002-018

A Magnetic Particle-Solid Phase RIA Kit for Microalbuminuria

Bhatkar

Smita

M.G.R.

Rajan

Apte

Priyanka

Short-term TraineesKetkar

Rashmi

Short-term Trainees

Laboratory Nuclear Medicine Section, Radio chemistry & Isotope Group, BARC, c/o TMH Annexe, Jerbai Wadia Road, Parel, Mumbai-400012.

Abstract

Microalbuminuria (MAU) is defined as the mild elevation in urinary albumin in the range of 20 - 200 µg/min or 30 -300 µg/ml, and is the earliest diagnostic marker of diabetic nephropathy. Hence, periodic monitoring (2-3 times a year) of patients with a diabetic history would be useful in detecting the onset of nephropathy and appropriate treatment can be initiated to delay the progress of the disease.

MAU is specifically measured by immunoassay techniques that are superior to dye-binding chemical methods. Of the immunoassay methods, Radioimmunoassay (RIA) is very robust and reliable and an in-house kit using bovine-Immunoglobulins and polyethylene glycol separation, has been in use for several years. The assay has been made user-friendly by using anti-HS A antibodies coupled to fine magnetic particles (1 -10µ). The standards are made in synthetic urine and the ¹²⁵I-HS A tracer prepared by labeling pure HS A to low a specific activity. The standards, Mag-HSA-Ab and even the ¹²⁵I-HS A have a long shelf life, making the kit useable for over two months.

The Mag-HSA RIA protocol has only three pipetting steps: 25 µl of std/sample is carried out in assay tubes, followed by 100µl of tracer and 1000 µl of Mag-HSA-Ab suspension. After a brief one-hour incubation on a shaker, the Mag-HSA-Ab is settled using a magnetic plate in a few minutes and the supernatant decanted. The assay has the required sensitivity, precision, short assay time and convenience of solid-phase for routine use. It correlates very well (r=0.95) with the existing assay, implying no change in the established normal ranges. The assay will soon be available in a kit form for use in screening/monitoring diabetic patients.

Key wordsMicroalbuminuriaurinary albumindiabetic nephropathyradioimmunoassay

References1

Mogensen

C.E.

Diabetes Care, 1995, 18,pp 572-5812

Borch-Johnson

Br Med J, 1993, 306, 1722-1725.

ijnm-20-4-poster002-019

Stability of 18F-FDG Synthesized at AIIMS PET Centre

SnehlataDhananjayRajivJayaPant

Malhotra

Bandopadhayay

Department of Nuclear Medicine, AIIMS, New Delhi-110029, India

Abstract

Aim of the Study was to find out the stability of 18F-FDG prepared in Nuclear Medicine, PET at AIIMS.

Materials and Methods

Reagents, solvents, gases, columns and other materials. Mannose Triflate, target material (H2 18O water), radioactive fluoride reagent, and other ingradients like anhydrous acetonitrile, HPLC grade water, Cryptofix, K2CO3, ethanol, 1N-HCl, Columns-Purification (packed with resinAG-11 andAG-50),alumina,C-18andQMA, TLCpaper and TLC Scanner, gases-P10, N2,compressed air, syringes -2ml, 5ml, 10ml, 20ml and 60 ml etc. and glasswares.

Procedure

The 18F-is obtained by the nuclear reaction 18O (p,n) 18F in the Cyclotron using 1.2 ml of enriched H218O (> 95%). At the end of bombardment the fluoride is transferred either directly to Explora FDG4 Box or through “V-Vial” by pressurizing with argon gas through QMA column. All kit components, precursor, reagents and accessories for the synthesis are ultra-pure degree and ready for use. The synthesis is achieved in 40-45 minutes by a nucleophilic substitution. The final product is purified by passing through purification column (combination of resin, Alumina and C18). The resulting neutral eluent was sterilized by 0.22 mm millipore and collected in a sterile production vial.

TLC was run in 95% methanol and scanned in TLC scanner at 0, 15, 30 mts and every hour upto 5hrs of the preparation to know the stability and Radiochemical Purity (RCP).

Results

18F-FDG was found to be stable upto five hours. It remained bound upto 98% in first one hour and upto 95% subsequently.

Conclusion

18F-FDG can be used upto five hours without any difficulty.

ijnm-20-4-poster002-020

Euthyroid CLT And Subclinical Hypothyroidism - Natural Course

Shankar

L. Ravi

Sripathy

Institute Of Nuclear Medicine And Allied Sciences Delhi-110054

Abstract

5-10% of chronic lymphocitic thyroiditis (CLT) which present in an euthyroid or compensated hypothyroid state invariably go into frank hypothyroidism in a year. This study was taken to find a possible cause for this. 50 consecutive patients with a cytological diagnosis of CLT, referred to the Institute of Nuclear Medicine and Allied Sciences at Delhi who were in an euthyroid (18 cases) or subclinical hypothyroid (SCH) (32 Cases) state were taken up for the study. Age of the patients varied 12-27 years (avg 18.1 +4.3). There were41 females and 9 males. CLT was diagnosed by the standard Fine Needle Aspiration Cytology technique, FT4 done by RIA (N 11.5 - 23 pm/l), TSH by RIA (N 0.17 - 5.2 uiu/l) and TPO antibodies by Electro chemiluminiscent assay (n<36iu). Mean FT4 levels were 14.03 +1.1 pm/l, TSH being 8.4 + 2.66 uiu/ml. 22 subjects with SCH and 10 euthyroid cases were detected to be TPO antibody positive. Patients were followed up for 24 + 4 months, being reviewed clinically 3-4 monthly and FT4 and TSH levels re-estimated 6 monthly. 6 cases of SCH and 2 euthyroid cases went into overt hypothyroidism during the follow up and were started on hormone replacement therapy. All subjects who became hypothyroid on follow up were TPO antibody positive.

Cases diagnosed as CLT on FNAC with TPO antibodies positive are more likely to go into overt hypothyroidism as compared to antibody negative subjects. We therefore recommended evaluation of these subjects with TPO Ab and 6 monthly follow up irrespective of hormonal status for timely detection and treatment of thyroid dysfunction.

ijnm-20-4-poster002-021

Useful Change In The Standard GFR/Differntial Renal Function Programme

Radhakrishnan

E.R.

Parameshwara

Nagaiah

H.J.

Murthy

K.S. Venkatesh

Department of Nuclear Medicine, Kidwai Memorial Institute of Oncology, Dr. Mh. Marigowda Road, Bangalore, India. Pin 560 029

Abstract

Renal radionuclide scintigraphic studies have been used in clinical nephrourology since 1960. Multiphase 99mTc DTPA renogram is routinely carried out in our department for evaluation of renal function. Studies were analysed using standard GFR/Differential protocol of SIEMENS ICON 9.5 KB 34 Clinical Software. It was observed in some normal renogram studies, that the time to peak activity (T_max) was less than one minute and time from peak to 50 % activity (T _1/2) was very less, which were clinically not correlating.

The macro GFR/Differential programms were reviewed and found that the entire range of curves was used for calculation of the T_max and T_1/2. It was due to the inclusion of the perfusion frames in the calculation, the T_max and T_1/2, values were found to be very low.

The programme was changed such that the perfusions frames were excluded for calculation of T_max and T _1/2. To check the correctness of the changed programme. Over 500 cases were evaluated and using the new programme. Now it was found that the T_max and T _1/2 were clinically correlating. The programme was again verified and confirmed by taking counts of the renogram curves.

We conclude that the perfusion frames should not be included for calculation of T_max and T_1/2.

Key wordsRenogramT_max & T_1/2

ijnm-20-4-poster002-022

Development of Indigenous HS A Nanocolloid Preparation for Use in Sentinel Lymph Node Imaging

Subramanian

Suresh

Pandey

Usha

Kothari

Kanchan

Grace

Samuel

Sarma

D Haladhar

Meera

Venkatesh

Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400 085

AbstractAim

To develop indigenous preparation of human serum albumin nanocolloid for use as a ^99mTc-labeled radiopharmaceutical in sentinel lymph node imaging.

Introduction

It is increasingly considered that surgical removal of sentinel lymph nodes along with the tumor will significantly lower relapse in cancers of breast and other organs without more aggressive measures like mastectomy or complete axillary lymph node removal. ^99mTc labeled human serum albumin (HSA) is currently used to identify sentinel nodes during surgery. With respect to the Indian scenario most kits used are imported and hence efforts must be made to develop an indigenous HSA kit for identifying sentinel nodes, to cover the needs of the Indian medical community.

Experiments and ObservationsNanocolloid Preparation

HSA nanocolloids were prepared using a reported procedure. Briefly, this involves reduction of ‘seeding’ amount of albumin using Sn(II) chloride followed by heating to obtain nuclei for nanocolloid formation. Remaining albumin is added with stirring for actual formation. Filtration through 0.22 mm filter removes higher size range particles. The nanocolloid preparation was lyophilized for prolonged storage. Particle size was estimated using dynamic light scattering (DLS) analysis. The obtained particle diameter was in the range of 70-100nm.

Technetium labeling

For labeling studies, ^99mTcO₄⁻ was added to a suspension of HSA nanocolloid and incubated for 10 min at RT. The procedure gave >95% yield as estimated by ITLC (Saline). Labeled preparation was found stable for 24hrs at room temperature.

Imaging Studies

Figure 1

Rabbit imaging studies showing the passage of ^99mTc-HSA nanocolloid and retention in the lymph nodes (Point of injection highlighted).

Imaging studies of labeled nanocolloid were performed in rabbit. The animal was injected in the footpad region with the labeled preparation and after a while the area was gently massaged to facilitate movement of the preparation. Planar static images were obtained at various time points (15,45,75,105 min) using a gamma camera.

The results are shown in Figure 1, clearly depicting gradual passage of the labeled preparation into the adjoining lymph nodes.

Conclusion

^99mTc-HSA nanocolloids were prepared indigenously and successfully tested. Further work towards clinical trials of the product is being addressed.

Key wordsSentinel nodeTumor imagingBreast cancer

ijnm-20-4-poster002-023

Biological studies for evaluation of Genistein towards development of a radiolabeled diagnostic/therapeutic agent for cancer

Suresh

Subramanian

Kanchan

Kothari

Meera

Venkatesh

Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400 085.

AbstractAim

To perform biological studies for evaluation of Genistein towards development of a radiolabeled agent for cancer nuclear medicine

Introduction

Genistein is a soybean isoflavone associated with reduced cancer risk in populations consuming high levels of soybean. It has been observed to inhibit proliferation of a variety of cancer cell lines, likely by multiple mechanisms of action¹, and is currently under clinical trials as a cancer therapy supplement. We have earlier prepared and characterized ¹²⁵I derivative of Genistein. The present study concentrates on in vitro cell uptake/displacement and in vivo biodistribution for biological evaluation of ¹²⁵I-labeled Genistein.

Experiments and ObservationsCell Uptake

Cell uptake was studied in MCF-7 human breast carcinoma line. At a fixed cell mass of 6 X 10⁵ cells/reaction, MCF-7 was subjected to various concentrations of ¹²⁵I-genistein for 2 hours at 37°C. Blanks with 100-fold cold Genistein were prepared. After incubation, cells were washed free of reaction medium and counted for retained ¹²⁵I activity from the labeled preparation.

Concentration-dependant uptake of ¹²⁵I-labeled Genistein was observed (Figure 1), which was appreciable in the micromolar range (~16%at1.2µM).

Uptake Displacement

Figure 1

Cell uptake of ¹²⁵I-Genistein in MCF-7.

Displacement of in vitro cell uptake of ¹²⁵I-labeled Genistein was studied by challenging the uptake observed at 1.2µM with competitive concentrations (0.5-8.0µM) of cold Genistein. Displacement of ¹²⁵I-genistein corresponded to addition of cold Genistein indicating that both had similar affinity to MCF-7.

In Vivo Distribution

Biodistribution was performed in Swiss mice. ¹²⁵I-labeled Genistein was administered intravenously and its biodistribution was assayed at various time points (1 hour, 3 hours, and 24 hours). Animals were immediately sacrificed at the end of the respective time points and their critical organs measured for retention of ¹²⁵I activity.

Long circulation time was observed for the labeled product. Activity pattern in liver and gastrointestinal tract indicates hepatobiliary clearance of the product.

Key wordsIsoflavonesGenisteintumor targetingcancer radiopharmaceuticals

References1

Dorai

Aggarwal

Cancer Lett., 2004; 215(2): 129-40.