Patients with MS with autoimmune features, including those with titers of antinuclear antibodies of 1:100 or less and/or antiphospholipid antibodies, are not different than others with MS, and therefore should not be excluded from clinical trials.
Most EPTs in VHL patients are somatostatin receptor scintigraphy-positive and malignant, without correlation with the VHL genotype. Surgical resection is often required, but prognosis of these EPTs seems to be fairly good.
In hemodynamically stable pulmonary embolism, BNP/troponin I measurement is helpful on admission, especially for ruling out RVD, i.e. patients with in-hospital high-risk.
Liver metastases are common in gastroenteropancreatic neuroendocrine tumors and significantly impair survival. Hepatic resection is the only potential curative treatment. The records of 41 consecutive patients undergoing exhaustive resection of liver-only endocrine metastases and followed between 1992 and 2006 were reviewed. Patient's outcome and diagnostic accuracy of somatostatin receptor scintigraphy (SRS) and morphological imaging (MI) for detection of recurrences during post-operative follow-up were assessed. All identified primary had been resected. MI studies including abdominal computed tomography (CT) and/or liver magnetic resonance imaging and thoracic CT if indicated were performed every 6 months; SRS timing was decided by referring clinician. Tumor recurrences were confirmed by pathology or subsequent imaging studies. The results of 136 MI and SRS examinations performed within a 30-day interval from each other were retrospectively compared. Median post-operative follow-up was 51 months (7-165). Recurrences developed in 32 patients (78%), mainly in the liver (nZ24) after a median of 19 months (2-79). Five-year overall and disease-free survival rates were 79 and 3% respectively. For recurrence detection, sensitivity, specificity, and accuracy were 89, 94, and 91% for SRS, 68, 91, and 74% for MI respectively. In 11 out of 32 patients (34%), abdominal or extra-abdominal metastases were detected 15.5 months earlier by SRS than MI. In conclusion, despite exhaustive liver surgery for endocrine metastases, hepatic or extra-hepatic recurrences are frequent and develop early. SRS is highly accurate for the detection of recurrences during post-operative follow-up and permitted early diagnosis in one third of patients; therapeutic implications of this early diagnosis remain to be determined.
To assess the impact of highly active antiretroviral therapy (HAART) on AIDS-associated cognitive impairment, 22 patients with AIDS with (n = 11) and without (n = 11) cognitive deficit were evaluated clinically and by MRS every 3 months for 9 months. Nineteen patients were on HAART at study entry, 21 after 2 months. Cognitively impaired patients presented with a subcorticofrontal deficit and decreased N-acetyl-aspartate in frontal white matter. These clinical and metabolic abnormalities reversed partially on HAART, whereas they remained within normal limits in cognitively unimpaired patients.
In our series, diffuse heterogeneous brain hypoperfusion is often the sole early objective imaging feature identified by SPECT of high-dose ara-C neurotoxicity, where MRI still demonstrates normal pictures.
Studying normal-appearing white matter on MRI with MRS allows discrimination between relapsing remitting and secondary progressive patients. In the NAWM of patients with MS and an SP course, severe axonal loss/dysfunction is negatively correlated to clinical disability and independent of the duration of the disease.
The radionuclides used in nuclear medicine imaging emit numerous mono-energetic electrons responsible for dose heterogeneity at the cellular level. S(self) the self-dose per unit cumulated activity (which results from the radionuclide located in the target cell), and S(cross) the cross-dose per unit cumulated activity (which comes from the surrounding cells) delivered to a target cell nucleus by electron emissions of technetium-99m, iodine-123, indium-111, gallium-67 and thallium-201 were computed at the cellular level. An unbounded close-packed hexagonal cell arrangement was assumed, with the same amount of radioactivity per cell. Various cell sizes and subcellular distributions of radioactivity (nucleus, cytoplasm and cell membrane) were simulated. The results were compared with those obtained using conventional dosimetry. S(self) and S(cross) values depended closely on cell dimensions. While the self-dose depended on the tracer distribution, the latter affected the cross dose by less than 5%. When the tracer was on the cell membrane, the self-dose was particularly low compared to the cross-dose, as the self-dose to cross-dose ratio was always less than 11%. In the case of cytoplasmic or cell membrane distribution of radioactivity, conventional electron dosimetry slightly overestimated the dose absorbed by the target cell nucleus (by 1.08-to 1.7-fold). In contrast, conventional dosimetry strongly underestimated the absorbed dose (1.1- to 75-fold) when the radioactivity was located in the nucleus. The discrepancies between conventional and cellular dosimetry call for calculations at the cellular level for a better understanding of the biological effects of radionuclides used in diagnostic imaging.
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