Impairment of cardiac metabolism and sympathetic innervation after aneurysmal subarachnoid hemorrhage: a nuclear medicine imaging study.

INTRODUCTION: Although aneurysmal subarachnoid hemorrhage (SAH) is often complicated by myocardial injury, whether this neurogenic cardiomyopathy is associated with the modification of cardiac metabolism is unknown. This study sought to explore, by positron emission tomography/computed tomography, the presence of altered cardiac glucose metabolism after SAH. METHODS: During a 16-month period, 30 SAH acute phase patients underwent myocardial (18)F- fluorodesoxyglucose positron emission tomography ((18)F-FDGPET), (99m)Tc-tetrofosmin and (123)I-meta-iodobenzylguanidine ((123)I-mIBG) scintigraphy, respectively, assessing glucose metabolism, cardiac perfusion, and sympathetic innervation. Patients with initial abnormalities were followed monthly for two months for (18)F-FDG, and six months later for (123)I-mIBG. RESULTS: In this SAH population, acute cardiac metabolic disturbance was observed in 83% of patients (n = 25), and sympathetic innervation disturbance affected 90% (n = 27). Myocardial perfusion was normal for all patients. The topography and extent of metabolic defects and innervation abnormalities largely overlapped. Follow-up showed rapid improvement of glucose metabolism in one or two months. Normalization of sympathetic innervation was slower; only 27% of patients (n = 8) exhibited normal (123)I-mIBG scintigraphy after six months. Presence of initial altered cardiac metabolism was not associated with more unfavorable cardiac or neurological outcomes. CONCLUSIONS: These findings support the hypothesis of neurogenic myocardial stunning after SAH. In hemodynamically stable acute phase SAH patients, cardiomyopathy is characterized by diffuse and heterogeneous (18)F-FDG and (123)I-mIBG uptake defect. TRIAL REGISTRATION: Clinicaltrials.gov NCT01218191. Registered 6 October 2010.

Distinct patterns of medial temporal impairment in degenerative dementia: a brain SPECT perfusion study in Alzheimer's disease and frontotemporal dementia.

PURPOSE: Medial temporal impairment can be detected clinically and by morphological imaging during Alzheimer's disease (AD), but the existence of a functional impairment in this area seems to be less well established. Yet such functional impairment is classically found in other degenerative cortical dementias, such as the frontal variant of frontotemporal dementia (fv-FTD). The aim of this study was to characterize and compare brain SPECT perfusion of the medial temporal lobe in AD and fv-FTD. METHODS: Voxel-based comparisons were performed using SPM8 between cerebral SPECT images from 85 AD patients, 25 fv-FTD patients and 12 healthy controls at the whole-brain level and the medial temporal lobe level using a region of interest approach (p < 0.001, corrected for the cluster). RESULTS: In the free and cued selective reminding test, used to evaluate medial temporal memory function, AD patients had significantly lower scores than the fv-FTD patients (p < 0.005). AD and fv-FTD patients showed hypoperfused medial temporal structures in comparison to normal controls. However, fv-FTD patients had more pronounced hypoperfusion in this area, with a different topography, more anterior and more parahippocampal. CONCLUSION: These results show that medial temporal hypoperfusion can be detected in degenerative dementias by SPECT. Paradoxically, the hypoperfusion is more severe in fv-FTD than in AD patients, even though the mnesic profile of AD is more altered, suggesting the existence of inefficient compensatory mechanisms.

A rare presentation of metastatic renal clear cell carcinoma to the tongue seen on FDG PET.

Renal clear cell carcinoma has a great metastatic potential, with possibly uncommon secondary lesions, notably in the head and neck region. The role of F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) in the staging or follow-up of urological malignancies is still not clearly defined. We report a case of metastatic renal cell carcinoma involving the tongue and a cervical lymph node, 3 years after initial nephrectomy. The use of combined positron emission tomography/computed tomography scan showed increased F-18 FDG activity in these 2 lesions that were then diagnosed and treated by surgery. Although the diagnostic performance of F-18 FDG PET is limited in the detection of primary disease, this imaging modality can be a very useful tool in the follow-up of renal clear cell carcinoma.