Lacrimal gland uptake of (67)Ga-gallium citrate correlates with biopsy results in patients with suspected sarcoidosis.

PURPOSE: To investigate whether lacrimal gland uptake on (67)Ga-gallium citrate scintigraphy correlates with histopathologic evidence of sarcoidosis. METHODS: A retrospective, pilot study of 31 patients with suspected sarcoidosis who underwent gallium scintigraphy and lacrimal gland biopsy. Lacrimal gland gallium uptake was assessed by subjective visual scoring (SVS) and lacrimal uptake ratio (LUR). RESULTS: Eleven (36%) patients had lacrimal gland biopsies containing noncaseating granulomas. A statistically significant correlation was found between lacrimal gland gallium uptake and biopsy positivity using SVS (p = 0.03) or LUR (p = 0.01). Using SVS, biopsy positivity rate increased from 0 to 50% in patients with mild to intense uptake. Using LUR, biopsy positivity rate increased linearly as the ratio increased from 13% (LUR < 4) to 100% (LUR > 8). CONCLUSIONS: Lacrimal biopsy positivity rate significantly correlated with gallium uptake on scintigraphy. Both SVS and LUR methods appear to correlate with histologic results and may potentially aid in patient selection for biopsy.

Physiology and pathophysiology of incidental findings detected on FDG-PET scintigraphy.

A routine feature of positron emission tomography/computed tomography (PET/CT) imaging is whole-body acquisition that results in many unexpected findings identified outside of the primary region of abnormality. Furthermore, (18)F-fluorodeoxyglucose (FDG) is a marker of glycolysis and does not specifically accumulate in malignancy. Understanding the physiology and pathophysiology of normal FDG distribution and common incidental findings is therefore essential to the physician interpreting whole-body FDG-PET/CT studies. Whereas many incidental findings are benign and of limited clinical significance, others represent uncommon manifestations of the primary malignancy, second malignancies, or various clinically significant pathologic processes. Patients with a single malignancy are at greater risk of developing synchronous or metachronous second malignancies, possibly related to exposure to shared carcinogenic agents or presence of prooncogenic mutations. The decision of how to pursue an intervention on the basis of an incidental finding is generally left to clinical judgment.

Dominant uptake of fatty acid over glucose by prostate cells: a potential new diagnostic and therapeutic approach.

BACKGROUND: Prostate cancer is characterized by a low rate of glycolysis and glucose uptake. We hypothesize that fatty acid is dominant over glucose in uptake by prostate cells. MATERIALS AND METHODS: One benign (RWPE1) and two malignant (LNCaP and PC3) prostate cell lines were assayed for their in vitro uptake of radiolabeled glucose analogs (3)H-fluoro-2-deoxyglucose and (18)F-fluoro-2-deoxyglucose, and the long-chain fatty acid (3)H-palmitic acid. Fractional uptake was standardized to viable cell numbers. RESULTS: Uptake of palmitate in all 3 prostate cell lines was significantly higher than that of glucose at all incubation times (p<0.01). But in malignant cell lines, neither glucose nor palmitate uptake was quantitatively higher than that in the benign cell line. The uptake of fatty acid by prostate cells is a dynamic, active process mediated by the membrane receptors. CONCLUSION: Prostate cells are characterized by a dominant uptake of fatty acid over glucose, suggesting that future development of new diagnostic and therapeutic approaches in prostatic cancer should focus on fatty acid substrate. Fatty acid imaging may be useful in detection of recurrence and metastasis, but not in differentiating malignant from benign prostate tissue.

18F-FDG PET evaluation of sinonasal papilloma.

OBJECTIVE: It has been suggested that (18)F-FDG uptake determined by PET can differentiate squamous cell carcinoma from benign sinonasal papilloma. We wish to present our experience with sinonasal papillomas and PET/CT to determine if the degree of FDG uptake is indicative of benign or malignant disease. CONCLUSION: Benign sinonasal papilloma may be associated with intense FDG uptake on PET/CT. FDG PET/CT does not appear to reliably differentiate benign from malignant sinonasal papilloma.

Use of whole-body FDG PET-CT to aid in the diagnosis of occult sarcoidosis.

PURPOSE: To report a case where combined whole-body Fluorine-18 fluorodeoxyglucose (FDG) PET-CT scanning was used to aid in the diagnosis of a patient with occult sarcoidosis. DESIGN: Case report. METHODS: FDG PET-CT scanning was performed in a patient who presented with persistent bilateral panuveitis after cataract surgery and had undergone an extensive negative workup. RESULTS: FDG PET-CT scanning demonstrated extensive mediastinal adenopathy. Biopsy showed a non-caseating granuloma with associated giant cell formation consistent with a diagnosis of sarcoidosis. CONCLUSIONS: FDG PET-CT scanning generates tomographic scans with excellent sensitivity, spatial resolution, and anatomical landmark identification and may be useful in the workup of idiopathic uveitis.

Tc-99m red blood cell scintigraphic detection of CMV-induced small bowel hemorrhage.

A 4-month-old female child, recently diagnosed with parentally-acquired HIV complicated by moderate immunosuppression and pneumocystis carinii pneumonia (PCP), presented with hematochezia. A Tc-99m bleeding study was performed and demonstrated a site of brisk bleeding in the distal ileum. The patient was taken to the operating room and resection of the distal ileum revealed the presence of cytomegalovirus (CMV) enteritis. In immunocompromised children presenting with gastrointestinal (GI) hemorrhage, CMV enteritis should be considered.

The F + 0 protocol for diuretic renography results in fewer interrupted studies due to voiding than the F - 15 protocol.

UNLABELLED: Timing of diuretic administration is not universally standardized in renography. Over the past year, our practice has changed from F-15 administration of furosemide to an F + 0 protocol. Therefore, we have retrospectively compared these 2 cohorts to assess if the shorter interval between diuretic administration and study completion in the F + 0 study results in a greater frequency of patients able to complete the subsequent 30-min dynamic acquisition without disruption due to voiding. METHODS: We identified 108 diuretic (99m)Tc-mercaptoacetyltriglycine renograms performed in the previous 18-mo period. Three patients were given furosemide at 30 min after the radiopharmaceutical and were excluded. Twenty studies in children under 3 y of age were excluded from consideration because voiding is neither restricted in this age group nor does voiding into a diaper cause disruption. Forty milligrams of furosemide were administered to adults, whereas 0.5 mg/kg was given to children. In the first cohort of 56 studies, radiopharmaceutical was administered 15 min after furosemide (F-15), whereas, in the second cohort of 29 patients, it was administered immediately thereafter (F + 0). In all cases, patients were asked to void proximal to radiopharmaceutical injection. Dynamic images and renogram curves were inspected for evidence of interruption or voiding midstudy. Statistical significance was determined by a 1-tailed Fisher exact test for proportions, with P < 0.05. RESULTS: The F-15 and F+0 groups of patients were comparable in terms of age, sex, and diuretic amount. In 17 of the F-15 patients, renography was interrupted because of voiding (30%), whereas this occurred in only 3 of the F + 0 patients (10%). This difference was significant at the P = 0.033 level. The mean time of voiding was 18.3 min (range, 12-25 min) for F-15 patients and 16 min (range, 12-19 min) for the F + 0 group. CONCLUSION: The F + 0 renal diuretic protocol is associated with a significantly lower rate of disruption because of voiding than the F-15 protocol, likely due to the shorter period between diuretic administration and study termination, which results in less bladder distention and discomfort. On the basis of these data, the F + 0 protocol appears to be a more tolerable procedure.

Fluorodeoxyglucose positron emission tomography excludes pericardial metastasis by recurrent lung cancer.

Fluorodeoxyglucose (FDG) positron emission tomography (PET) has been shown to be useful in the diagnosis and staging of a variety of malignancies. Because of its high sensitivity, FDG PET frequently detects malignant lesions that are not demonstrated clearly by anatomic imaging modalities. FDG PET usually has high negative predictive value and, therefore, negative studies are highly suggestive of a benign process. The authors present a patient in whom transesophageal echocardiography and magnetic resonance imaging described pericardial metastasis from a recurrent lung cancer, which on FDG PET was shown correctly to suggest benign scar tissue.