Analysis of the effects of injecting drug use and HIV-1 infection on 18F-FDG PET brain metabolism.

UNLABELLED: Injecting drug use (IDU) is a major risk factor for contracting HIV-1 infection. Both HIV and IDU are neurotoxic, and their coexistence may lead to increased dysfunction of brain metabolic processes. The objective of this research was to investigate the effects of HIV-1 infection and IDU on (18)F-FDG PET brain metabolism. METHODS: (18)F-FDG PET brain imaging, with a standard clinical protocol, was performed on 59 subjects who belonged to 3 groups: HIV-positive/IDU-positive (n = 17), HIV-negative/IDU-positive (n = 13), and HIV-negative/IDU-negative controls (n = 29). A voxel-based analysis of the (18)F-FDG PET brain images was performed using statistical parametric mapping. The images were spatially normalized to a standard (18)F-FDG template, proportionally scaled to compensate for count differences, and then appropriately smoothed. Statistical 2-sample t tests were performed to determine regional metabolic distribution differences in the 3 groups. RESULTS: Diffuse hypermetabolism in the subcortical and deep white matter, the basal ganglia, and the thalami was observed in HIV-1 infection. IDU resulted in increased brainstem metabolism and decreased activity in cortical structures including bilateral medial frontal lobes and the right inferior frontal and temporal cortices. The cortical hypometabolism was more extensive in HIV-1-infected subjects, involving the left temporoparietal and right parietal cortices and bilateral medial frontal lobes. CONCLUSION: Voxel-based analysis of (18)F-FDG PET brain images demonstrated statistically significant differences in regional metabolism for the 3 studied groups. It also showed that HIV-1 infection may have a synergistic effect with IDU, resulting in more extensive cortical hypometabolism. Correlation of these findings with other quantitative approaches and neurocognitive functioning is warranted.

MIBG and FDG PET findings in a patient with malignant pheochromocytoma: a significant discrepancy.

Radionuclide imaging has proven to be very useful when dealing with neuroendocrine tumors and several radiotracers are currently available. One of the most commonly used and widely accepted methods to image pheochromocytomas is I-131 metaiodobenzylguanidine (MIBG) scintigraphy. However, recent studies with positron emission tomography (PET) using 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in pheochromocytomas have shown that FDG PET imaging can be useful in those pheochromocytomas (usually malignant) that fail to accumulate MIBG. The therapeutic plan of malignant pheochromocytoma can include chemotherapy and/or a high dose of I-131 MIBG, so precise staging and characterization is mandatory for correct management and treatment.

A renal protocol for all ages and all indications: mercapto-acetyl-triglycine (MAG3) with simultaneous injection of furosemide (MAG3-F0): a 17-year experience.

Current clinical requirements mandate the existence of a renal diuretic protocol, which is fast and easy, applicable in all ages and for all indications, convenient for both the patient and the technologist, and provides diagnostic as well as prognostic information. Seventeen years ago a 25-minute protocol, after oral hydration, with no bladder catheterization, and simultaneous injection of mercapto-acetyl-triglycine (MAG(3)) and furosemide (MAG(3)-F(0)), was initiated. It initially was used for the evaluation of drainage and emerged as a protocol to also evaluate the renal parenchyma. Results of this protocol have been published individually, per clinical application. MAG(3)-F(0) was instrumental in the evaluation and prognosis of congenital disorders. For obstruction, in the newborn, an increasing renogram mandates intervention, whereas a downsloping one predicts spontaneous resolution. In children or adults, preoperatively or postoperatively, when the cortex was visualized and drained normally, there was no obstruction, even if urine was retained within a dilated collecting system or an extrarenal pelvis. For diseases of the renal parenchyma, the protocol enabled the diagnosis of acute pyelonephritis (APN) revealing the "regional parenchymal dysfunction," diagnostic of APN. Diffuse parenchymal diseases were characterized by increased residual cortical activity (RCA), and their progression was manifested as a deterioration of RCA. End-stage renal disease was characterized by lack of accumulation and retention. Trauma and leaks were identified with specific patterns. In renovascular hypertension (RVH), an increase in RCA after angiotension-converting enzyme inhibitors is diagnostic of RVH and prognostic of the beneficial effect of angioplasty on hypertension. In renal colic, stratification was possible into (1) complete or severe obstruction requiring immediate intervention, (2) mild obstruction allowing waiting, (3) spontaneous decompression (stunned kidney), and (4) no recent obstruction. In transplants, it enabled differentiation of acute tubular necrosis, acute or chronic rejection and nephrotoxicity, and identified infarcts, RVH, leaks and obstruction. Finally, this method allows for a quick semiquantification of renal function. The clinical usefulness of the MAG(3)-F(0) protocol in most congenital or acquired renal problems is proven through long-term clinical experience and has resulted in a substantial utilization of the test at our Center.