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Vol . 8 No. 3 June 2000  

Clinical & Defence-Related Services

Diagnostic Nuclear Medicine

Clinical nuclear medicine is no more an exotic and experimental branch of medicine in India. Due to significant role played by DRDO as technology assimilator, demonstrator and disseminator, nuclear medicine technology is now easily accessible (there are more than 150 centres in the country today) and has now a well-established role in therapeutic and diagnostic branches of medicine. The cost per investigation has come down due to reduction in overheads. For several decades, a DRDO laboratory was the only nuclear medicine centre in the entire North India apart from AIIMS which generally catered to its own indoor patients. Currently, it is doing all relevant nuclear medicine tests free of cost for defence personnel and their families, and at subsidized rates for civilians referred by a tertiary government hospital.

Besides, common clinical diagnosis is also carried out, where radiological investigations are of limited use but are solved by nuclear medicine in a non-invasive and cost-effective way. These facilities available for public and defence personnel and their family members are :

Genitourinary System

Tc-99m DTPA renal scan can quantitate absolute and differential renal function. Even 5 to 10 per cent of the
renal function can be detected, while IVP reports a nonfunctioning kidney if the function falls by 60 per cent or
more. This information helps urologist to plan nephrectomy or more conservative surgery.

In identifying the urinary pathway obstruction, renal scintigraphy is superior to the conventional IVP, particularly in units with impaired function. It saves many unnecessary surgeries in case of functional obstruction and is useful in documenting the success after surgery.

Tc-99m DMSA scan identifies scar in the previously infected kidney. The technique has significantly better accuracy than ultrasonography. Direct retrograde cystography gives information about the presence of vesicouretric reflux with a distinct advantage of  significant less raDIATion burden to the patient.

Captopril renal scan is a non-invasive effective method to screen young hypertensives for the presence of renal artery stenosis. This technique could also be used to follow up such patients after a corrective procedure like renal artery angioplasty.

Non-invasive follow up of patients with renal transplant is another area in which the renal scan is of immense help. In the differentiation of torsion of testis from acute epidydmo-orchitis, the nuclear scan very effectively differentiates the two, thus providing an appropriate treatment approach to a case of painful scrotal swelling.

Cardiology

Cut section of human heart with prominent left ventricle.Cardiac scan using agents like thallium-201, Tc-99m MIBI or Tc-99m Myoview can diagnose coronary artery disease with greater sensitivity and specificity than TMT and stress Echo. It eliminates the need for angiography (and possibly coronary bypass) in many patients. It can accurately assess benefits of coronary artery bypass surgery and can be repeated many times without any morbidity.

The left ventricular function is assessed by MUGA study where Tc-99m labeled RBCs are used. It gives useful information about the ejection fraction and also about the regional wall motion analysis. This study is of particular use in the patients receiving cardiotoxic drugs.

Skeletal Imaging

Bone scan is a simple and highly sensitive technique to determine any abnormality in skeleton. It becomes positive with as little as 2 to 5 per cent alteration in bone metabolism unlike a radiogram abnormality which requires an alteration of about 40 to 50 per cent before a lesion could be identified. It plays a major clinical role in assessing the cancer spread to the bone. It plays a significant diagnostic role in sport injuries and diagnosis of bone infection and necrosis. When complemented with MRI, the bone scan appears to be the final word in bone traumatology.

Gastroentrology

Very common problems, like unknown bleeding site in intestines, meckel's diverticulum, and presence of gastroesophageal reflux are diagnosed easily. Although the presence of cholelithiasis is best seen by an ultrasound examination, Tc-99m DlSIDA scan is the most sensitive way to demonstrate acalculus cholecystitis. Gall bladder stones are very common in population and all do not need surgery. This scan helps the surgeon to identify cases fit for surgery. This procedure is again the best for evaluation of post cholecystectomy syndrome or detection of any biliary leak. The nuclear scan can provide insight in the heptobiliary kinetics in both pre- and post-operative state.

Endocrinology

Use of radioiodine and pertechnetate scan for thyroid has been going on from the time nuclear medicine came into existence. The scan still has a distinct role in management of thyroid disorders. Present day practice of nuclear medicine has introduced specific imaging methods of cancer thyroid management like radiolabelled DMSA (V), MIBG or CEA for medullary cancer of thyroid and TI-201 or Tc-99m MIBI for other forms of thyroid cancer. Thallium-technetium subtraction scan offers a unique approach to study parathyroid hyperplasia and adenoma in case of hyperparathyroidism. 1-131 MIBG is used not only for diagnosis but also for the treatment of pheochromocytoma, neuroblastoma, carcinoid and other neural crest tumors.

Oncology

Nuclear medicine offers a non-invasive method for diagnosis, staging, treatment and follow up of oncology patients where the role of radiological procedures may be limited. Tc-99m MIBI, TI-201 and more selective approaches like labeled monoclonal antibodies are used for the purpose.

Infection

It is sometimes difficult to identify the focus of infection in the body. Nuclear medicine techniques like Tc-99m labeled ciprofloxacin, Tc-99m dextran or Tc-99m hlgG are currently available with DRDO. This is a result of indigenous technology application and the techniques have been shown to be better than the one using conventional agents, in one or more ways. These have been found particularly useful for bone infections and intestinal inflammations, including tuberculosis. The agents are also useful in cases with PUO, AIDS or prosthesis where convention algorithm does not reveal the site of infection.

Others

Nuclear procedures are also available for brain disorders (evaluation of stroke, epilepsy, dementia etc.), vascular studies and others. Many times, radio pharmaceuticals and protocols are not conventionally fixed, these are chosen according to the clinical problem and information desired.