(18)F-2-fluoro-2-deoxyglucose uptake in or adjacent to blood vessel walls.

Incidental (18)F-2-fluoro-2-deoxyglucose (FDG) uptake in blood vessel walls is sometimes demonstrated during routine oncologic imaging with positron emission tomography/computed tomography (PET/CT). FDG uptake in vessel walls can also be seen under some non-physiological conditions such as vasculitis and arteriosclerosis. Radiologists need to be aware of the diseases which can exhibit FDG uptake in the vessel wall for proper interpretation.

Postprocessing technique with MDCT data improves the accuracy of the detection of lung nodules.

PURPOSE: The aim of this study was to determine whether postprocessing techniques could improve the accuracy of detecting lung nodules. MATERIALS AND METHODS: A total of 154 segmented lung volumes of multidetector-row computed tomography (MDCT) data were the subject of the study. Lung nodules were present in 88 volumes and absent in 66 volumes. We prepared four groups: (1) 7- or 10-mm thick-section axial images; (2) 1-mm thin-section axial images; (3) sliding slab maximum intensity projection (MIP) images with a slab thickness of 15 mm; and (4) sliding slab volume rendering (VR) images with a slab thickness of 15 mm. Sixteen physicians reviewed each group in interactive cine mode. The observers' performance in the detection of lung nodule was evaluated by receiver operating characteristic (ROC) analysis. RESULTS: The observers' performance of the MIP and VR groups was significantly better than in other two groups. There was no significant difference statistically between the thin and thick groups. CONCLUSION: The detectability of lung nodules is improved with the use of sliding slab MIP and VR using thin-section image data. Thin-section volume data are essential for improving diagnostic accuracy, but observation of thin-section images without utilization of image-processing techniques dose not improve diagnostic accuracy.

Elevation of plasma oxidized LDL in acute stroke patients is associated with ischemic lesions depicted by DWI and predictive of infarct enlargement.

Oxidized low-density lipoprotein (OxLDL) plays a major role in atherosclerosis. We undertook the present study to clarify the relationship between plasma OxLDL and the ischemic volume. We used ELISA to determine plasma OxLDL levels, and performed diffusion- and perfusion-weighted MRI (DWI, PWI) to measure the ischemic volume in 44 ischemic stroke patients. Based on the location of the ischemic lesion, they were divided into three groups: Group I (GI, n = 21) had cortical lesions, Group II (GII, n = 17) had lesions in the basal ganglia or brain stem, and Group III (GIII, n = 6) had massive lesions that involved one entire hemisphere. In GI, but not GII and GIII, plasma OxLDL was significantly higher than in 19 age-matched controls (p < 0.01) and was significantly correlated with the initial ischemic volume visualized on DWI (p = 0.01), PWI (p < 0.01), and the DWI-PWI mismatch (p < 0.05). A persistent increase in plasma OxLDL was associated with enlargement of the ischemic lesion in the early phase after the insult. These findings suggest that elevated plasma OxLDL levels are associated with moderate ischemic damage in patients with cortical lesions (GI), but not those with massive hemispheric lesions (GIII), which may be irreversible. In addition, elevated plasma OxLDL may represent a predictor of enlargement of the ischemic lesion.

Two cases of retroperitoneal hematoma caused by combination of anticoagulant therapy and 5-fluorouracil.

We reported two cases of retroperitoneal hematoma in patients who received a combination of anticoagulant therapy and 5-fluorouracil (5-FU). We should be aware of the possible interaction of this combination therapy and monitor prothrombin time (PT) prolongation. CT is useful for evaluation of the disease.

Three-dimensional imaging of thoracic diseases with multi-detector row CT.

The benefits of multi-detector row CT (MDCT) relative to single-detector row helical CT are considerable. Multi-detector row CT allows shorter acquisition times, greater coverage, and superior image resolution. These factors substantially increase the diagnostic accuracy of the examination. Three-dimensional (3D) volume data from MDCT provides various unique applications on thoracic diseases. These includes isotropic viewings, use of multiplanar reformation (MPR), maximum and minimum intensity projections (MIP and minIP), and volume rendering performed from external and internal perspectives allowing the user to "fly around" and "fly through" the structures. Recent advances in 3D volume rendering put real-time, interactive virtual reality guidance of the procedures such as bronchoscopy and surgery into practice.

Correlation between flow-sensitive alternating inversion recovery perfusion imaging with different inversion times and cerebral flow reserve evaluated by single-photon-emission computed tomography.

The purpose of this study was to evaluate the effect of different inversion times (TIs) on flow-sensitive alternating inversion recovery (FAIR) perfusion imaging and compare them with the cerebral blood flow reserve evaluated by acetazolamide challenge using single-photon-emission computed tomography (SPECT). The subjects were nine patients with unilateral obstruction of the internal carotid artery. The signal ratio (SR16/8) of two images with different TIs (1,600 ms and 800 ms) was calculated, and the cerebral blood flow reserve (CFR) was evaluated by the increase in the ratio of cerebral perfusion after administration of acetazolamide in the SPECT study. A reversed linear correlation ( r=0.75) was found between SR and CFR, indicating that differences of FAIR images with changes of TI will be affected by cerebral flow reserve.

Comparison of FAIR technique with different inversion times and post contrast dynamic perfusion MRI in chronic occlusive cerebrovascular disease.

The purpose of this study was to examine the signal change occurring with different inversion times (TIs) of the flow-sensitive alternating inversion recovery (FAIR) technique and to compare with the perfusion image obtained with Gd-DTPA injection. The subjects were 11 patients with unilateral occlusive cerebrovascular disease. Two FAIR images with different TIs (800 ms and 1600 ms) were measured for each patient and dynamic perfusion MRI was performed to produce four kinds of parameter maps: mean transit time (MTT), time to peak (TTP), relative cerebral blood flow (rCBF) and relative cerebral blood volume (rCBV) maps. Asymmetry ratios (ARs) between the affected and contra-lateral vascular sides were measured in both FAIR images and the four dynamic parameter maps. The AR of the MTT map of the four parameters showed the highest correlation with that of the FAIR images, especially with that of TI = 1600 ms (r = 0.829), and the AR of the rCBV map revealed the worst correlation with the FAIR images. The AR of the FAIR image with TI = 800 ms was less correlated with that of MTT than that with TI = 1600 ms. These results suggested that the signal intensity of the FAIR image was influenced by flow transition time and the change in TI could be used to select the flow with a different transition time. Our study suggested that a longer TI in the FAIR technique might be more useful than a shorter TI for evaluating chronic occlusive cerebrovascular disease in the clinical setting.

Can diffusion- and perfusion-weighted magnetic resonance imaging evaluate the efficacy of acute thrombolysis in patients with internal carotid artery or middle cerebral artery occlusion?

OBJECTIVE: The value of combined diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) for detecting ischemic lesions of patients with acute ischemic injury was analyzed. Combined pre- and posttreatment DWI and PWI studies were used to assess the efficacy of intra-arterial thrombolysis. METHODS: Intra-arterial thrombolysis was performed within 6 hours of onset in 10 patients who presented with acute middle cerebral artery or internal carotid artery occlusion. DWI and PWI obtained before and after treatment were studied. The final T2-weighted magnetic resonance scans were obtained 1 month after onset. Thrombolysis resulted in recanalization in seven patients. The mismatch ratio percentage ([initial PWI-initial DWI/initial PWI] x 100) and the rescued ratio percentage ([initial PWI-final T2/initial PWI] x 100) were calculated. The National Institutes of Health Stroke Scale (NIHSS) was used for neurological assessment of stroke severity at admission and at 1 month after onset. RESULTS: In all patients, the mismatch ratio was greater than 60% (mean +/- standard deviation, 81.7 +/- 16.7%) and was significantly correlated with initial NIHSS score (-0.74; P = 0.03), and the rescued ratio was significantly correlated with the NIHSS score 1 month after the insult (r = -0.83; P = 0.01). In patients who exhibited recanalization of the occluded artery (n = 7), the mean rescued ratio was 89.6 +/- 12.8% (range, 63-100%). In addition, the lesion volume on posttreatment DWI scans and final T2-weighted magnetic resonance images was not enlarged; on posttreatment PWI scans, it was significantly decreased. The NHISS score at 1 month after the insult (2.3 +/- 2.1) was markedly improved as compared with the initial NHISS score (10.7 +/- 3.9). CONCLUSION: In a small number of patients who presented with internal carotid artery or middle cerebral artery occlusion, the DWI/PWI mismatch ratio correlated with the initial neurological severity. The rescued ratio may be an objective indicator of the efficacy of treatment.