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Vol . 8 No. 3 June 2000  

Research & Development in Nuclear Medicine

Important contributions of DRDO to nuclear medicine science can be categorised as follows. Almost all of these are examples of how simple and low-cost concepts can be put to immense practical use for the benefit of patients.

Oncology

  • Thyroid perfusion scan using pertechnetate was confirmed by DRDO as a reliable technique to suspect malignancy in solitary thyroid nodules which were detected as normal by conventional methods.
  • Utility of Tc-99m citrate was proven in scinti-mammography (for screening breast malignancy). Cost of the study is only 20 per cent of that of conventional radiopharmaceuticals used for the purpose.
  • Tc-99m DMSA M was established as a sensitive mean to detect medullary cancer of thyroid. Further work has shown that its uptake in this particular malignancy may be due to its incorporation in amyloid tissue associated with this type of malignancy.
  • Combination scan of Tc-99m sulphur colloid and Tc-99m RBC was found of practical use in evaluating liver masses into benign hemangioma and malignant hepatoma.
  • 24/3 hr steroid interventional bone scan technique was developed to identify malignant lesions out of those seen on a routine bone scan. The technique gives valuable information without adding to the cost or raDIATion hazard to the patient. The need for additional radiological procedures is circumvented by this technique.
  • Tc-99m citrate was identified as a new bone imaging agent. Comparison with the conventional bone scan
    established its superiority. The test has been shown to be more specific for identifying bone metastases.

Infection/Inflammation Imaging

Conventional agents like Tc-99m MDP bone scan and Ga-67 citrate are considered non-specific and have fallen into disrepute. Labelled white-cell imaging is costly, hazardous and technically not suitable for most Indian centres. DRDO has developed and tested several new techniques and radiopharmaceuticals for the purpose.

  • Peripheral osteomyelitis:   Tc-99m ciprofloxacin is the preferred agent for peripheral bone infections including tuberculosis and painful prosthesis evaluation. For joint infections and traumatic lesions, however, Tc-99m dextran is more suitable. Main use of the tracer is in follow-up of the disease process. It is useful in diagnosis if frontline radiological tests are non-confirmatory. Clinical advantage of the tracers is being utilized by the Army Hospital, New Delhi, amongst others.
  • Vertebral osteomyelitis: It is synonymous with tubercular infection in Indian context. For reasons yet unknown, most agents except Tc-99m citrate prove Insensitive in this condition. This tracer is now routinely used for diagnosis and follow up of tuberculosis of the spine.
  • Tc-99m dextran: It has proved extremely sensitive in detecting and evaluating inflamed lesions of the intestine, such as ulcerative colitis, Mackel's diverticulum and other occult lesions of the intestine.
  • Tc-99m ciprofloxacin: It is valuable in diagnosis and follow up of pelvic inflammatory disease in females and in evaluating fever of unknown origin.

Gastrointestinal & Hepatobiliary System

  • Tc-99m dextran is recommended for detecting site of intestinal bleeding and confirming suspected protein-losing enteropathy whether generalised, regional or focal. DRDO suggests that it is the most sensitive test available for the purpose and for detecting Macke\'s diverticulum which is quite difficult to diagnose preoperatively in children.
  • DRDO experience with Tc-99m DISIDA indicates its diagnostic role hitherto unsuspected in biliary dyskinesia. This may be the underlying cause of unexplained abdominal pain in a large number of patients, specially after intestinal or biliary surgery. Simple administration of sublingual nifedipine during the test was found to increase its sensitivity as well as specificity.
  • In-house studies using milk scan prove that abnormal reflux of stomach acid into the esophagus is a major cause of asthmatic attacks in children, particularly those suffering from a posture deformity and related disorders.