Malignant melanoma and (18)F-FDG-PET: Should the whole body scan include the legs?

AIM: (18)F-FDG-PET (FDG-PET) is established in staging and follow-up of malignant melanoma. The legs are affected in 10-40% at time of diagnosis even if the primary is at the arms and torso. Imaging including the legs may detect distant manifestations but increases duration of the scan by approximately 30 min. We intended to disclose the diagnostic benefit of scanning the legs and to evaluate the therapeutic benefit resulting. PATIENTS, METHODS: In this retrospective analyse 213 consecutive PET studies of 153 patients with suspected or recent malignant melanoma were re-evaluated for metastatic spread by a blinded investigator. Histopathological follow-up was assessed for confirmation. RESULTS: Suspicious findings at the legs were depicted in 53 patients on 76 occasions. 38/53 showed pathologic uptake in the torso as well. In 15/53 patients it was restricted to the legs. One of them had a hitherto unknown, clinically relevant finding that was not apparent in palpation and inspection. In 6 other patients with primary location at the legs a validation of the positive PET findings was not possible up to now. CONCLUSION: Metastases and local recurrence of malignant melanoma at the legs were found in 41% of women and 27% of men. However, a long scan does not yield relevant additional data. We found isolated new manifestations at the legs in only 1/153 patients. We recommend performing a long scan only in patients with previous melanoma manifestations restricted to the legs. In all other cases a short scan of the torso and proximal thighs is sufficient. This allows a higher number of PET-scans without loss of diagnostic power and a shorter examination time.

I-123-lodo-alpha-methyl tyrosine SPECT in non-parenchymal brain tumours.

PURPOSE: Scintigraphy using I-123-iodo-alpha-methyl tyrosine (IMT) is useful in the preoperative characterization of gliomas, in detecting recurrent glioma and in the biological re-evaluation of residual or recurrent tumours. A systematic evaluation of non-parenchymal brain tumours has not yet been performed. The aim of the present study was to evaluate IMT SPECT in the management of intracerebral metastases and lymphomas. PATIENTS AND METHODS: IMT uptake was analyzed in 31 patients with 28 metastases of extracerebral solid tumours and 7 cerebral lymphomas. Histology revealed high grade lymphomas, melanomas, and carcinomas of the following origin: lung, unknown primary, breast, colon, renal cell, ovary, vagina, frontal sinus. IMT uptake was quantified as ratio between maximal tumour accumulation and average uptake in the contralateral hemisphere. RESULTS: All tumours except two renal cell and one small cell lung carcinoma metastases accumulated IMT (91%). The highest IMT uptake was found in a metastasis of lung carcinoma. IMT uptake was highly variable and was similar in primary and in recurrent tumours. CONCLUSION: Significant accumulation of IMT is seen in the majority of tumours, so that this technique might be helpful for the management of cerebral metastases and lymphomas.

Moyamoya syndrome: impaired hemodynamics on ECD SPECT after EEG controlled hyperventilation.

BACKGROUND AND PURPOSE: Ischemic symptoms in children with Moyamoya syndrome are typically provoked by hyperventilation (HV) and are accompanied by the "re-build-up" phenomenon in EEG. The value of scintigraphic detection of HV-provoked perfusion deficits remains to be elucidated. PATIENTS AND METHODS: In seven children with Moyamoya syndrome regional cerebral blood flow was assessed by 99mTc-ethyl-cysteine-dimer (ECD) single photon emission computed tomography (SPECT) after HV and under baseline conditions to identify ischemia prone regions. RESULTS: Regional marked hypoperfusion after HV was found in all patients. Predominant perfusion deficits were detected in the frontal lobes. CONCLUSION: ECD SPECT is a potential tool for the preoperative evaluation of cerebral hemodynamics and for monitoring angiosurgical therapies in Moyamoya disease.