NEC density, representing count statistics per body volume, reflects the visual image quality assessment and may be utilized for quality control of whole-body FDG-PET images together with the liver ROI S/N ratio.

Objective: To evaluate the advantage of upright position imaging with a medium-energy collimator for the detection of sentinel lymph node (SLN). Methods: Thirty-four patients with operable breast cancer underwent sentinel node lymphoscintigraphy with 99m Tc-tin colloid. Images were obtained in 5 different positions and paired images from the same patient were compared using side-by-side interpretation. Images were compared in 3 groups: group 1 (anterior view); supine (SAV) vs. upright (UAV), group 2 (oblique view); supine (SOV) vs. upright (UOV), and group 3 (oblique view); modified supine (MOV) vs. UOV. Image quality was evaluated using a 3-grade scale of clear, faint, and equivocal depiction, and correlated to 3 parameters: distance from injection site to lymph node (hot node), counts in hot node, and image contrast. Parameters in group 1 were compared by classifying the primary tumor site into 4 subregions. Results: Image quality in all 3 groups was more enhanced on the image obtained in the upright position than that in the supine position. Obtaining images in an upright position increased the mean distances by 1.5-3.2 cm, and mean contrasts were significantly increased by 0.13-0.31 (p < 0.05). It was shown that image quality was more greatly affected by image contrast than by counts in the hot node. Image contrast of 0.5 seemed an appropriate threshold level for detection of the hot node. On comparison of tumor sites, the upper outer quadrant (C) region of the 4 subregions demonstrated greater contrast enhancement on upright position images. Conclusion: Clinical images obtained in an upright position with a mediumenergy collimator were superior to those obtained in a supine position. Use of this procedure is recommended to enhance lymph node detection on sentinel node lymphoscintigraphy.

No abstract

We report a case of bronchogenic carcinoma with atelectasis studied by T1-SPECT and FDG-PET. In the carcinoma, abnormally high uptake of T1 and FDG were detected, but in the region of atelectasis, an abnormally high uptake of T1 with a relatively low uptake of FDG were observed. On quantitative analyses, the T1 retention indexes of the tumor and atelectasis were 29.7 and 42.0. The mean SUVs of FDG of the tumor and the atelectasis were 8.92 and 1.28. T1-SPECT could not distinguish the atelectasis from the carcinoma. FDG-PET was superior to T1-SPECT in this case in detecting malignancy and distinguishing it from atelectasis.

Cerebral blood flow and metabolism were evaluated in an adult with symptomatic intractable epilepsy and Sturge-Weber syndrome (SWS) manifesting as angiomas in the left cerebral hemisphere. 99m Tc-ethylcysteinate dimer single photon emission computed tomography detected reduced blood flow in the entire left cerebral hemisphere, and [ 18 F]fluorodeoxyglucose positron emission tomography (PET) showed decreased glucose metabolism in the left cerebral hemisphere. These findings indicated hypofunction of the left cerebral hemisphere, which caused the right hemiparesis. 11 C-methionine ( 11 C-Met) PET revealed high 11 C-Met accumulation in the angiomas in the left cerebral hemisphere. Immunostaining for glial fibrillary acidic protein showed positive reaction in the lesions. Gliosis is a likely mechanism for the 11 C-Met accumulation, which is possibly associated with progressive calcification in the angiomas and retarded growth of patients with SWS occurring over many years.