Abstract

IJNM

Indian Journal of Nuclear Medicine

0972-3919

Society of Nuclear Medicine, India

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Oral 1

122004

2049599

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Brain Perfusion in Different Stages of Japanese Encephalitis

Barai

Gambhir

Vandana

Department Of Nuclear Medicine, SGPGIMS Lucknow

AbstractObjective

There is a paucity of regional cerebral blood flow studies in cases of Japanese Encephalitis (JE) with none of the studies available to assess brain perfusion abnormalities in all the three stages of the disease. This study is done to evaluate changes noted in brain perfusion in acute, sub acute and chronic stages of JE as detected by single photon emission computed tomography (SPECT) Material And Methods: Between December 2000 and September 2005,31 patients (19 men and 12 women: mean age 49 years) of various stages of JE [Acute stage n = 5, Sub acute stage n =17, and Chronic stage n = 9] underwent brain perfusion scintigraphy using Tc-99m labeled ECD. Upto 7 days of onset of symptoms was considered to be acute stage, 7 to 56 days was considered to be sub acute stage and any duration beyond 56 days was considered chronic stage.

Results

In acute stage all the 5 patients demonstrated focal areas of hyper perfusion involving mainly the thalamus. Bilateral thalami involvement was noted in 3 patients. Frontal lobe involvement was noted in 4 patients and parietotemporal lobes in 1 patient. In the sub acute stage hypo perfusion was noted in all the patients. The subgroup of patients in the chronic stage demonstrated hypo perfusion as well as normal perfusion. 4 patients showed hypo perfusion, whereas no perfusion defects were noted in 5 patients. Conclusion: Brain perfusion abnormalities observed depends on the stage of the disease. In the acute stage there is focal hyper perfusion to sites of active viral replication, in the sub acute stage focal hypo perfusion is noted due to virus induced damage to cellular protein synthesis machinery and finally perfusion returns to normal due to regeneration of cellular organelles. These results also confirm high frequency of thalamic involvement in JE.

Key wordsJapanese Encephalitis (JE)Brain SPECT

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Renal Perfusion Scintigraphy to Evaluate Pathophysiological Changes in Unilateral Calculus Disease

Sethi

Karun

¹Bansal

Rajesh

²Datta

Mita

¹Gupta

Sanjay

²Kashyap

Ravi

¹Div. of Nuclear Medicine, INMAS, Brig. S.K. Mazumdar Road, Delhi-110 054²Dept. of General Surgery, GTB Hospital and University, College of Medical Sciences, New Delhi

Abstract

Renal/ureteric stone is a common cause of urinary tract obstruction (UTO), which can be diagnosed anatomically by X-ray KUB/USG. The line of management however depends upon the functional implications of the stone, which can be assessed by IVP/Renal scan. The cascade of events, which lead to the pathogenesis of obstructive nephropathy, include increase in the tubular hydrostatic pressure, which leads to compromise in the renal medullary blood supply. In response to this medullary ischemia there is a transient rise is renal blood flow (RBF) mediated by PGE₂, prostacyclin and NO but within a short duration of acute complete obstruction, this transient response is blunted by an increase in the production of endothelin and thromboxane, and activation of Renin Angiotensin System. This in turn leads to a profound vasoconstriction leading to a drastic drop in RBF and the Glomerular Filtration Rate (GFR). This is the stage where renal perfusion scintigraphy can be used as a modality to predict the onset of obstructive nephropathy, which is actually caused as a result of irreversible interstitial fibrosis due to recruitment of macrophages in the ischemic medulla and cortex. Relying upon the excretory phase of the renogram and the effect of diuresis (as per SNM guidelines) might lead to a loss of precious time during which an early intervention would lead to a significant reversibility in the functional status of the kidney.

Materials and Methods

40 patients (20 males and 11 females, having a mean age of 31) of acute renal colic diagnosed as having unilateral ureteric/renal calculus on X-ray KUB/US G were referred for renography. A two-phase radio nuclide renography was performed on each patient with Tc99m DTPA. In the first phase perfusion images were acquired in 32 frames of 2 seconds each followed by the second phase having 75 frames of 16 seconds each. Diuretic intervention was done when required at 15 minutes of the study. The renograms were also assessed to comment upon the severity and type of obstruction on the basis of clearance T_1/2.

Results

All the renograms as well as the composite perfusion images showed a significant reduction in the perfusion in the ipsilateral kidney. 8 (20%) cases however did not suggest obstructive pattern (T_1/2 being les than 10 minutes) on the renogram. The T_1/2 was noted to be more than 20 minutes in rest of the cases.

Conclusion

This study clearly indicates that renal perfusion scintigraphy gives the treating surgeon a chance to intervene at an earlier stage so that a reasonable recovery in the renal functions may be achieved. However, more studies are required to justify the use of renal perfusion scintigraphy on routine basis in every patient of UTO.

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Clinical Relevance of DTPA lung Clearance Data in Patients with Interstitial Lung Disease

Somali

Gavane

Krishna

P D Hinduja National Hospital and MRC, Mumbai

AbstractBackground

Interstitial Lung Disease is commonly diagnosed on HRCT with specific patterns of ground glass and fibrosis. However the activeness of the disease prior to and after therapy is difficult to assess on the CT scan alone. Since the disease primarily affects the alveolar membrane, the DTPA aerosol clearance from the alveoli would be a sensitive indicator of the active or inactive nature of the disease.

Method and Results

Totally 12 patients were included in our prospective study. The CT scan was the initial diagnostic modality.

The DTPA aerosol clearance rate was calculated from the time activity curve generated from the dynamic ventilation images obtained after inhalation of DTPA aerosols. There were 10 patients where both CT and DTPA clearance was abnormal of which 8 patients were on steroid therapy. The abnormal DTPA clearance suggested persistence of active disease. In 2 patients where the DTPA clearance was normal of which one patient showed persistence of ground glass appearance on CT scan while the other patient showed regression of changes seen on pretreatment study.

Conclusion

From the above study we conclude that DTPA aerosol clearance rate is a reliable and sensitive indicator of active disease in interstitial lung disease. The segmental analysis would help in accurate characterization of extent of improvement on treatment.

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Quantitation of Normal Regional Cerebral Perfusion on Tc99m ECD Brain SPECT

Parmar

Bhattacharya

Singh

Prasad

Mittal

Department of Nuclear Medicine, PGIMER, Chandigarh-160012, India

AbstractIntroduction

SPECT brain perfusion scintigraphy is a useful tool in the management of many neurological and psychiatric disorders. A normal database of age-matched controls is essential for accurate assessment of subtle perfusion anomalies. However, a reliable quantitative database of normal subjects is not readily available. This study was carried out to identify normal regional cerebral perfusion in a small group of adults.

Materials and Methods

14 volunteers without any obvious physical, neurological or psychiatric disorders were selected for the study. Two distinct age groups were represented, one comprising 8 male adults aged 25-29 years (26 ± 2.3) and the second of 6 adults (3M, 3F) aged 51-61 years (54 ± 3.9). Imaging was performed under a dual head gamma camera fitted with low energy high-resolution (LEHR) collimators 40 minutes after intravenous administration of 15-20 mCi of Tc99m-ECD. Images were acquired in a continuous circular orbit, using 128 projections (20 seconds each) over 360 degrees, in a 128 x 128 matrix. The image data thus acquired was processed by filtered back projection using a Butterworth smoothing filter with a cutoff frequency of 0.5 and order 10. Attenuation correction with a co-efficient of 0.125 and threshold value 5 was applied. Mid-transverse slice in the orbitomeatal plane followed by additional images in the sagittal and coronal planes were generated.

Bilaterally symmetrical circular/ovoid regions of interest (ROIs) were marked over the frontal, temporal, parietal, and cerebellar regions, as well as the thalami and basal ganglia in the transverse, sagittal and coronal planes. Average radioactive counts per pixel were measured for each ROI. The values for each region were compared to the corresponding ipsilateral cerebellar counts and the ratios recorded.

Results

Region wise ratios for the young male group ranged from 0.78 for the left thalamus to 1.10 for the right frontal lobe, and from 0.76 (right thalamus) to 1.01 (right caudate) in the older adult group. Detailed list of ratios will be presented.

Conclusion

This study was able to establish a range of constant perfusion ratios in different cerebral cortical and subcortical regions in a small group of normal adults. These ratios may be used for identification of minor regional perfusion anomalies in various clinical disorders in a corresponding age group.

Key wordsTc99m ECD SPECTBrainQuantitationNormal

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Use of Bacterial Endotoxin Test (BET) in Quality Assurance and Quality Control of Radio pharmaceuticals

Pilkhawal

Neelam

Karkhanis

Barakha

Board of Radiation and Isotope Technology

Abstract

Gram-negative bacteria have lipopolysacchride (LPS) in the outer membrane of their cell wall that is toxic to specific host. This LPS is called endotoxin because it is toxin and bound to the bacteria and released when the microorganism lyses. Endotoxins cause a response in humans ranging from mild fever to shock or even death. Traditionally rabbit pyrogen test, was used for detection of pyrogens, which was based on monitoring the rise in temparature of rabbit after injection of substance. Since endotoxins account for most of the pyrogens, BET is fast replacing pyrogen testing. The BET is an in-vitro test utilizing ly sate of blood cells of the horseshoe crab (species Limulus), which enzymatically interacts with endotoxin. Presence of endotoxins can be detected by checking for formation of solid gel (i.e. gel-clot method) or by incorporation of turbidometric or colorimetric assay.

This Limulus amebocyte lysate (LAL) test is very sensitive, relatively easy to set up and has been extensively used by nuclear medicine laboratories. The main advantage of this technique is it requires less sample volume and also the test is rapid and convenient and invitro. BET for ready to use radiopharmaceuticals like ¹⁵³ Samarium EDTMP, ¹³¹I-MIBG, ³²P-sodiumorthophosphate, ⁵¹Cr-Sodium chromate, ¹⁸F-Flurodeoxy glucose were carried out by gel-clot technique.

For assuring the quality of final products, the vehicles such as water for injection and saline used in the pharmaceutical preparations are also tested for BET. In the process of standardization of the procedure, test for interference was also carried out. Over the period of two years, many batches of radiopharmaceuticals were tested for BET and in case of ready to use radio-pharmaceuticals failure rate of 5% was found. For assuring the quality of the product and finding cause of failure, troubleshooting was carried out by analyzing vehicles at different dilutions or by re-autoclaving of vehicles. This experience has enabled better practices leading to lower failure rates.

In short BET is, sensitive, in vitro, rapid especially for short lived radio-pharmaceuticals where product can be released for administration to humans after the completion of test, without appreciable loss of radioactivity.

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Iodine-124 Production and Specific Activity Evaluation

Atilio

Anzellotti

¹Alexander

Yordanov

¹Robert

Ylimaki

¹Maximb

Kiselev

¹Eastern Isotopes, Inc./IBA S.A., Virginia Commonwealth University, Richmond VA 23298, U.S.A.²Eastern Isotopes, Inc./IBA S.A., 100 Executive Dr., Suite 100, Sterling VA 20166, U.S.A.

Abstract

Figure 1

Synthesis of 1-iodo-2-naphthol.

Iodine-124 (¹²⁴I) is an attractive isotope of iodine due to its complex radioactive decay scheme and convenient half-life (4.18 d). With the increasing use of positron emission tomography (PET) in nuclear medicine, medical oncology, pharmacokinetics and drug metabolism, ¹²⁴I-labeled radiopharmaceuticals could be most useful for PET imaging.¹ Furthermore, the 4.18 d half-life would permit their use in PET facilities far away from the radionuclide production centers. Limited availability of this radionuclide so far has been a hindrance to its wider development and clinical use. Recently, ¹²⁴I became commercially available, and this has accelerated the development of ¹²⁴I-based PET imaging agents. For example, sodium [¹²⁴I]iodide is reportedly useful for diagnosis and treatment planning in thyroid disease. Another one, [¹²⁴I]m-iodobenzylguanidine ([¹²⁴I]MIBG) holds potential for cardiovascular imaging as well as for diagnosis and treatment planning in malignant diseases such as neuroblastoma, paraganglioma, pheochromocytoma, and carcinoid. The achievement of a radiopharmaceutical preparation possessing the optimal specific activity and radiochemical purity always requires a radiohalogen starting material with no-carrier-added (NCA) specific activity as close to the theoretical carrier-free (CA) specific activity as possible. We have evaluated the NCA SA of sodium [¹²⁴I]iodide batches produced by the ¹²⁴Te (p,n)¹²⁴I reaction using the i-iodo-2-naphthol method. For method calibration, 1-iodo-2-naphthol was prepared according to the Scheme.

For the SA measurements of sodium [¹²⁴I]iodide batches, the later were treated with 2-naphthol in the presence of chloramin-T and the concentrations of the resulting 1-iodo-2-naphthol and 1-bromo-2-naphthol were determined by their UV absorbances. This technique allows for the quantification of even traces of iodine and bromine, due to the high extinction coefficients of their corresponding 1-halo-2-naphthol derivatives.²

References1

Glaser

Luthra

S.K.

Brady

Int. J. Oncology, 2003, 22, 253-267.2

Kloster

Laufer

J. Label. Comp. Radiopharm., 1983, 20, 1305-1315.

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Radiation Level In and Around PET/CT Facility at AIIMS

Kumar

Rajeev

Pant

Senthamizhchelvan

Malhotra

Dept. of Nuclear Medicine, AIIMS, New Delhi

AbstractIntroduction

Positron emission tomography (PET) is a nuclear imaging modality that has rapidly gained favor. ¹⁸F-FDG is the most widely used radiopharmaceutical with a half-life of 109.8min. ¹⁸F decays predominantly by positron emission, which leads to annihilation production of a pair of coincident 0.511 MeV photons. The specific gamma ray constant (Γ) of all positron emitters is considerably higher than those of conventional isotopes. For instance Γ of ¹⁸F is about 3 and 8 times higher than that of ¹³¹I and ^99mTc respectively. Hence radiation safety is of paramount important as far as PET/CT facility is concern.

Objective

The aim of this study is to survey the radiation levels in and around a newly commissioned PET/CT facility at the All India Institute of Medical Sciences, New Delhi.

Materials and Methods

A layout of the PET/CT facility has been drafted. High exposure level points were identified and radiation survey had been carried out in those particular locations. The radiation survey has been carried out using a calibrated RAM GAM-1 survey meter (Rotem Inc. Israel). Radiation levels were monitored around patient waiting hall with two patients injected with 10mCi ¹⁸F-FDG. Radiation dose to technologists performing the scan were also measured during positioning of patients. The exposure level from patients administered with 10mCi ¹⁸F-FDG was measured immediately, at the time of scanning and after the scanning was over.

Results and conclusion

The radiation survey in and around the PET/CT facility showed that the dose levels out side the scanning room varied from 0.3 - 4 mS v/hr. The dose levels at various distances from the patient just after administration of 10 mCi ¹⁸F-FDG and at the time when their scanning is completed is given table-1. It is therefore important for the staff to keep a distance from the patient unless otherwise it is necessary such as during positioning. With proper use of radiation safety guidelines it appears that the dose levels of the staff involved in dose administration and scanning may be well within recommended prescribed limits. The radiation survey in a PET/CT facility is a must from radiation safety point of view and it would also help in improving work practice of the concerned staff. Table 1

Dose levels (average of 5 patients) at various distances from the patient (injected dose 10 mCi 18F-FDG)

location	Body surface	0.5m	1m	2m

Dose level just after dose administration (µSv/hr)	875	107	41	16
Dose level after scanning (µSv/hr)	323	52	20	9.8

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Subclinical Hypothyroidism; A Separate Disease Entity

Mitra

Sujata

Muthu

G.S.

Tata Main Hospital (TMH), Jamshedpur

AbstractIntroduction

Subclinical Hypothyroidism is a syndrome with normal Thyroxine (T₄) and mildly elevated Thyroid Stimulating Hormone (TSH)¹

Aim of the present paper is to study differences in clinical presentation and response to treatment in Subclinical and overt Hypothyroidism.

Materials and Method

The study included 269 patients. Total T₄ (RIA) and TSH (IRMA) were assayed in all patients. In patients with normal T₄, raised TSH, the latter was re-assayed after four weeks. The patients were divided into two-Group A (n=168) consisted of patients with low T₄, raised TSH, Group B (n=75) of patients with normal T₄, raised TSH. Patient's clinical details were recorded before starting Thyroxine 100 mg/more in Group A and 50 mg daily in Group B respectively. Clinical follow -up was monthly. TSH was assayed six weeks after therapy and repeated annually.

Observation

The clinical presentation is given in Table-1. Table 1

Clinical profile

Clinical Profile	Group A	Group B

Age 21-40 years	52.7%	56%
Male: Female	1:74	9:159
Follow up of 1-5 years	81.5%	78%
Asymptomatic	Nil	38%
Weight gain	42%	Nil
Goiter	23.2%	10%
Menstrual irregularity	21.4%	24.5%
Infertility	10.1%	14.8%

The response to Thyroxine replacement is presented in Table 2. Table 2

Response to treatment

Improvement in clinical profile	Group A	Group B

Goiter	84%	92%
Menstrual regulation	72%	88%
Fertility	63%	84%

4% of patients in Group A and 2% in Group B showed biochemical and clinical evidence of hyperthyroidism during treatment requiring a reduction in Thyroxine dose. No build up of Thyroxine dose was required in Group B patients during the follow up period.

Conclusion

The need for Thyroxine replacement in Subclinical Hypothyroidism is controversial.¹ The present study showed benefit in such patients presenting with menstrual irregularity, infertility and goiter. There was no escalation in the requirement of Thyroxine during treatment period. This could possibly indicate mild, non-progressive disease.

Subclinical Hypothyroidism appears to be a separate disease entity, with clinical presentation different to Overt Hypothyroidism. It responds well to low dose Thyroxine replacement.

Key wordsSub-clinical HypothyroidismOvert HypothyroidismThyroxine replacementbenefit

References1

Cooper

David S.

‘Subclinical Hypothyroidism’

NEJM, 2001, Volume 345, Number 4, 260-265

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Analysis of 1400 Cases of Thyrotoxicosis

Bhagat

Department of Nuclear Medicine, Command Hospital (EC), Kolkata-27

Abstract

Results of treatment of 1400 patients of thyrotoxicosis with radioiodine (131 I) are presented. Median follow up was 4 years. Treatment was successful in 1053 (75.2%) while 347 (24.8%) were not controlled with single dose and required retreatment. 140 (10%) cases required third dosefor reaching final treatment. Incidence of hypothyroidism in the first year was 20% and annual increment of hypothyroidism was 1.2%. Age, sex and thyroid hormone values before treatment had no influence on outcome but size of goiter had a direct relationship viz, larger goiters were associated with higher treatment failures. Larger goiters were given more than 5 mci I-131 dose. Need for formula based procedures to calculate the required amount of 131-I for therapy is a good guide for deciding higher doses of radioiodine. Delivered radiation dose of 7000 rads is considered necessary to produce desired therapeutic effect. Table 1

^99mTc-Radiopharmaceuticals	System: Solvent (Support)	Main Impurity	Radiochemical Purity

Sodium pertechnetate	Acetone (Whatman No 3)	RHT	Not less than 95%
Tc-Sulphur colloid	Acetone/Methanol (whatman No 3)	FT& RHT	Not less than 90%
Tc-DTPA	a) Acetone/MEK (Whatman No 3)	FTRHT	Not less than 90%
Tc-DTPA	b) Saline (whatman No 3)	FTRHT	Not less than 90%
Tc-GHA	a) Acetone/MEK (Whatman No 3)	FTRHT	Not less than 90%
Tc-GHA	b) Saline (whatman No 3)	FTRHT	Not less than 90%
Tc-PHYTATE	Acetone/Methanol (Whatman No 3)	FT& RHT	Not less than 90%
Tc-MDP	a) Acetone/MEK (Whatman No 3)	FTRHT	Not less than 90%
Tc-MDP	b) Saline (whatman No 3)	FTRHT	Not less than 90%
Tc-DMSA	a) Acetone/MEK (Whatman No 3)	FTRHT	Not less than 90%
Tc-DMSA	b) Saline (whatman No 3)	FTRHT	Not less than 90%
Tc-MEBROFENIN	a) MEK (Pretreated Whatman No 3)	FTRHT	Not less than 90%
Tc-MEBROFENIN	b) Methanol (ITLC SG)	FTRHT	Not less than 90%
Tc-ECD	Methanol (Whatman No 3)	FT & RHT	Not less than 90%
Tc-EC	a) Acetone (Whatman No 3)	FTRHT	Not less than 90%
Tc-EC	b) Water:Acetonitrile (1:1) (Whatman No 3)	FTRHT	Not less than 90%

FT:- Free pertechnetate
RHT :- Reduced hydrolysed technetium

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QTECH - a user friendly easy to use Quality control test kit for ^99mTc-Radoipharmaceuticals

Ghodke

S Archana

Vanaja

Prabhakar

Sachdev

Pandey

Mehra

Radopharmaceuticals Programme, BRIT; Navi Mumbai, India

Abstract

Radiochemical purity assessment is an important quality control parameter as it indicates purity and integrity of the labeled product. The conventional method available for Radiochemical purity assessment are time consuming. Also the hospital radiopharmacy s a busy unit catering to the imaging/diagnostic needs of several patients on daily basis the conventional Q.C. testing may not be feasible. There is no such product available from a manufacturer in India which help to assess radiochemical purity in a reasonably short time. Hence need for the rapid procedures for evaluating the RCP of Tc-RPS formulation at the hospital end.

A large number of nuclear medicine physicians and technologists had expressed on various occasions, a need for such kit with which the quality of Tc-labeled RP products can be checked rapidly at the hospital. Based on this demand this kit has been configured. QTECH is made specially for use at hospital radiopharmacy. It is a Q.C. test kit consisting of solvents, miniature chromatography strips and the booklet for the RCP protocol procedures. There are total six protocols for eleven products. The miniature procedure employ chromatography paper and ITLC media (8 cms in length) and takes only 20 mins for the experiments This method is developed for the rapid determination of Tc-labeled product, TcO₄ and RHT as conventional Q.C. test using long strip paper chromatography is time consuming and takes ~2 h for the experiments.

The final product protocol procedures are the result of optimizing various parameters namely selection of suitable solvents, duration of paper chromatography run, size of the paper etc. to arrive at an easy to use procedure. All the Tc-RPS were tested for RCP by using miniature chromatography. Results were comparable to conventional RCP determination methods.

Key wordsQTECHRadiochemical PurityRadiopharmaceuticalsTechnetiumKit