Iranian Journal of Nuclear Medicine
Volume:5 Issue: 1, 1997

We describe a patient with newly diagnosed limy cancer. Staging was performed with CT and mediastinoscopy. FDG PET scan was performed and confirmed increased metabolic activity in the primary tumor as well as the hilar lymph node. Seven months after initial presentation, the patient was found to have two lytic lesions in the pelvis on plain radiograph. Hone scan was negative but PET demonstrated FOG uptake in one lesion. The possible utility of whole body FDG PET in detecting osseous metastasis is discussed. The state-of-the-art of staging lung cancer is also reviewed.

Markedly elevated111 In labeled leukocyte activity suggestive of acute osteomyelitis was observed in a region of a composite mandibular allograft that was photon deficient on 99mTc MDP bone scintigraphy. This finding was later confirmed by surgical pathology. The patient was treated with intravenous antibiotics and returned two months later with persistent bone infection. The foHow-up three phase bone and 111In labeled leukocyte scans were performed. The photopenic region noted in the previous bone scan demonstrated a mild interval increase in activity, while the 111In labeled leukocyte activity was essentially normal. Additional imaging of the composite allograft was then performed using 67Ga-citrate at 24 and 48 hours post injection. These images revealed focal areas of increased Gallium activity in the photopenic region of the graft exhibiting normal mIn leukocyte activity. The tissue culture comfirmed underlying chronic osteomyelitis. We conclude that normal uptake on niIn labeled leukocyte and photon deficient regions on 99mTc bone scintigraphy do not necessarily exclude the presence of chronic osteomyelitis. In the management of patients who have been on prolonged antibiotic therapy with persistent infection, 67Ga scintigraphy is warranted.

Testicular scintigraphy has been well validated in the evaluation of patients with suspected testicular torsion and provides an accurate evaluation of testicular perfusion at the lime of imaging. However, the presence of normal or increased perfusion to the testis does not definitively exclude the necessity for surgical intervention. A case of intermittent testicular torsion, with a review of testicular scintigraphy in the evaluation of the acute scrotum arc presented.

This study was conducted to determine the prevalence of PE in patients with V/Q scans interpreted as representing a very low probability (VLP) of PE (1-3 small segmental perfusion defects with a normal chest radiograph). An analysis of the entire data set obtained during the PIOPED study was performed. Of the total of 1,359 patients in whom the presence or absence of PE was confirmed, 80 (6%) patients had the VLP pattern. Only 2 of 80 patients (2.5%) had PE, both patients had partially occlusive thrombus within a single lower lobe segment. Both patients were also referred from surgicl wards, had a history of previous surgery within 3 months and a history of immobilization within 3 days prior to scan. Both patients with PE and VLP patterns had intermediate pretest odds. However, 36 patients with similar lung scan findings and no evidence of PE also had intermediate pretest odds. The remaining 40 patients had low pretest odds (two patients did not have pretest odds entered into the data base). We conclude that the very law probability interpretation criterion is a valid diagnostic category and should be a separate part of any schema for interpreting V/Q lung scans. The pretest clinical likelihood of PE did not change the post test probability of PE for very low probability lung scan interpretation as they did for low, intermediate or high probability lung scan interpretations.

A man with metastatic carcinoma of the colon had a bone scan which revealed urinary retention in the leftkidney. Ten months later, a Tc-99m-DTPA renai glomerular study showed the left kidney to have only 8% oftotal renal function. Fifteen months after that, (he same kidney demonstrated 9% of total function, while theright kidney had evolving obstruction due to his neoplasm. The case shows that loss of a significant amountof renal activity can occur over relatively short intervals, but that a small degree of functional activity canpersist.

This study was undertaken to examine the ability of SPECT in differentiation of a pulmonary lesion suspecions of lung cancr. A total of 170 patients with suspected lung cancer were studied. A dose of Tl-201 chloride {148-296 MBq) was injected intravenously and tomographic early and delayed scans were obtained at 15 miniutes and 3 hours post injection, respectively. Delayed Tl-201 SPECT visulized all of the 147 malignant pulmonary lesions which were clearer than those obtained by the early SPECT. Tl-201 SPECT seems to be a useful method for assessing pulmonary tumors and it offeres the retention index useful for differentiating malignant from benign lesions, and mediastinal involvement from lung cancer.