T2-weighted turbo spin-echo images, maximum-intensity projections, and three-dimensional volume-rendering for delineation of pathologies and anatomic details of the inner ear.

PURPOSE: The aim of the current study was to compare 3-dimensional T2-weighted turbo spin-echo (TSE) axial slices, maximum-intensity projections (MIPs), and volume-rendered images with respect to the delineation of pathologic findings and anatomic structures of the inner ear. Each of the compared image types was available at 2 different resolutions. MATERIALS AND METHODS: In 64 patients, 3-dimensional T2-TSE images were acquired with a matrix of 128 x 100 and 230 x 230 (field-of-view 90 x 90 mm). Direct axial images, MIPs, and volume-rendered images from the 2 datasets were evaluated in terms of the delineation of pathologic findings and anatomic structures. Analysis was performed by 2 radiologists in consensus. RESULTS: Though axial images acquired with a matrix of 230 x 230 showed more anatomic details than images acquired with a matrix of 128 x 100, pathologic findings (33 in total) were assessable with the same confidence on images of either resolution. Pathologies completely surrounded by fluid were best assessed on axial slices. The delineation of pathologies not embedded in a fluid was almost equally good in axial slices, MIPs, or 3-dimensional volume-rendered images. CONCLUSION: Reading the axial images cannot be replaced by viewing postprocessed reconstructions for initial diagnosis, because only some of the pathologies can be delineated on MIPs and volume reconstructions. However, reconstructions can be valuable for assessing the extent of pathologies and their spatial relation to the anatomic structures.

pO(2) Polarography versus positron emission tomography ([(18)F] fluoromisonidazole, [(18)F]-2-fluoro-2'-deoxyglucose). An appraisal of radiotherapeutically relevant hypoxia.

BACKGROUND AND PURPOSE: The aim of the present study was to validate ([(18)F] fluoromisonidazole (FMISO) and [(18)F]-2-fluoro-2'-deoxyglucose (FDG) positron emission tomography (PET) for determination of radiotherapeutically relevant hypoxia by the gold standard for measuring tissue oxygenation in human tumors, the computerized polarographic needle electrode system (pO(2) histography). PATIENTS AND METHODS: Up to now, a total of 16 patients with a metastatic neck lymph node from a primary squamous carcinoma of the head and neck underwent pO(2) and PET measurements. Tumor tissue pO(2) was measured with polarographic needle electrodes using a pO(2) histograph (Eppendorf). Under CT control, the needle electrode was placed in the tumor without general or local anesthesia. To assess the biological and clinical relevance of oxygenation measurement, the relative frequency of pO(2) readings, with values < or = 2.5, < or = 5.0, and < or = 10.0 mmHg, as well as mean and median pO(2) were recorded. All PET studies were carried out using an ECAT EXACT 922/47 scanner with an axial field of view of 16.2 cm. FMISO PET consisted of one static scan of the relevant region, performed 120 min after intravenous administration. The acquisition and reconstruction parameters were as follows: 15-min emission scanning and 4-min transmission scanning with (68)Ge rod sources. FDG PET of the lymph node metastasis was performed 68 +/- 11 min after intravenous administration, applying the whole-body tool with 8-min emission scanning and 4-min transmission scanning per bed position. RESULTS: In order to detect possible relations between the different relevant polarographically measured parameters of tumor hypoxia and FMISO PET data-based oxygenation values, the Pearson correlation coefficient was calculated. Average (r > 0.5) to high correlation (r > 0.7) was found between tumor-to-muscle ratio of FMISO after 2 h and parameters of hypoxic fraction (pO(2) readings with values