The utility of the combined use of 123I-FP-CIT SPECT and neuromelanin MRI in differentiating Parkinson's disease from other parkinsonian syndromes.

BACKGROUND: Neuromelanin magnetic resonance imaging (NmMRI) and 123I-FP-CIT dopamine transporter single photon emission computed tomography (DAT-SPECT) provide specific information that distinguishes Parkinson's disease (PD) from non-degenerative parkinsonian syndrome (NDPS). PURPOSE: To determine whether a multiparametric scoring system (MSS) could improve accuracy compared to each parameter of DAT-SPECT and NmMRI in differentiating PD from NDPS. MATERIAL AND METHODS: A total of 49 patients, including 14 with NDPS, 30 with PD, and five with atypical parkinsonian disorder (APD) underwent both NmMRI and DAT-SPECT and were evaluated. The average (Ave) and the asymmetry index (AI) were calculated in the substantia nigra compacta area (SNc-area), SNc midbrain-tegmentum contrast ratio (SNc-CR), and specific binding ratio (SBR). Cut-off values were determined, using receiver operating characteristic (ROC) analysis, for the differentiation of PD from NDPS on the statistically significant parameters. All cases were scored as either 1 (PD) or 0 (NDPS) for each parameter according to its threshold. These individual scores were totaled for each case, yielding a combined score for each case to obtain a cut-off value for the MSS. RESULTS: The Ave-SNc-area, Ave-SNc-CR, and Ave-SBR in PD were significantly lower than those in NDPS. The AI-SNc-area and AI-SBR in PD were significantly higher than those in NDPS. Of the five parameters, the highest accuracy was 93% for the Ave-SNc-area. For the MSS, a cut-off value of 3 was the accuracy of 96%. Besides, no significant difference was observed between PD and APD on all parameters. CONCLUSION: An MSS has comparable or better accuracy compared to each parameter of DAT-SPECT and NmMRI in distinguishing PD from NDPS.

Myocardial Delayed Enhancement CT for the Evaluation of Heart Failure: Comparison to MRI.

Purpose To assess the diagnostic performance of dual-energy CT with myocardial delayed enhancement (MDE) in the detection and classification of myocardial scar in patients with heart failure, with late gadolinium enhancement (LGE) MRI as the standard of reference. Materials and Methods MDE CT and LGE MRI were performed in 44 patients with heart failure (30 men; mean patient age, 66 years ± 14) between 2013 and 2016, and images were retrospectively analyzed. The presence and patterns of MDE on iodine-density and virtual monochromatic (VM) images were assessed by two independent readers. Contrast-to-noise ratio (CNR) and percentage signal intensity increase relative to normal myocardium were measured. Diagnostic performance and area under the receiver operating characteristic curve for MDE CT and kappa values for reader agreement were determined. Results Thirty-five of the 44 patients (80%) demonstrated a focal area of LGE, with a nonischemic pattern in 22 of the 44 patients (50%) and an ischemic pattern in 13 (30%). Iodine-density images demonstrated the highest CNR and percentage signal intensity increase on CT images (P < .05), resulting in the highest diagnostic performance in the detection of any MDE CT abnormality (92% sensitivity [195 of 213 segments] and 98% specificity [481 of 491 segments]). The areas under the receiver operating characteristic curve for iodine-density images and 40-keV VM images in the detection of MDE were 0.97 and 0.95, respectively (P < .001). Kappa values for reader agreement were 0.82 for iodine-density images and 0.72 for 40-keV VM images. Conclusion Myocardial delayed enhancement CT enables accurate detection and localization of scar in patients with heart failure when compared with late gadolinium enhancement MRI, the reference standard.

Utility of intravoxel incoherent motion magnetic resonance imaging and arterial spin labeling for recurrent glioma after bevacizumab treatment.

Background Detecting recurrence of glioma on magnetic resonance imaging (MRI) is getting more and more important, especially after administration of new anti-tumor agent. However, it is still hard to identify. Purpose To examine the utility of intravoxel incoherent motion (IVIM) MRI and arterial spin labeling-cerebral blood flow (ASL-CBF) for recurrent glioma after initiation of bevacizumab (BEV) treatment. Material and Methods Thirteen patients (7 men, 6 women; age range = 41-82 years) with glioma (high grade, n = 11; low grade, n = 2) were enrolled in the study. IVIM parameters including apparent diffusion coefficient (ADC), true diffusion coefficient (D), and perfusion fraction (f) were obtained with 14 different b-values. We identified tumor progression during BEV therapy by MRI monitoring consisting of diffusion-weighted imaging (DWI), fluid-attenuated inversion recovery (FLAIR) imaging, and contrast-enhanced T1-weighted (CE-T1W) imaging by measuring tumor area. We also measured each parameter of IVIM and ASL-CBF, and calculated relative ADC (rADC), relative D (rD), relative f (rf), and relative CBF (rCBF) by obtaining the ratio between each area and the contralateral cerebral white matter. We calculated the rate of change (Δ) by subtracting values from those from the preceding MRI study, and obtained Spearman's rank correlation coefficient (rs). Results Tumor progression was identified in nine patients (high grade, n = 7; low grade, n = 2). Negative correlations were identified between ΔrD and ΔDWI area (rs = -0.583), and between ΔrD and ΔCE-T1W imaging area (rs = -0.605). Conclusion Tumor progression after BEV treatment can be identified by decreasing rD.

Evaluation of Parkinson's disease by neuromelanin-sensitive magnetic resonance imaging and 123I-FP-CIT SPECT.

Background Both neuromelanin-sensitive magnetic resonance imaging (NmMRI) and 123I-FP-CIT single photon emission computed tomography (SPECT) (DaTSCAN) assist the diagnosis of Parkinson's disease (PD). However, there have been few studies investigating a correlation between them. Purpose To correlate the utility of NmMRI and DaTSCAN and to evaluate the relationship between both imaging findings and the Unified PD rating scale part III (UPDRS III) score for the diagnosis and management of PD. Material and Methods Seventeen patients with PD who underwent both NmMRI and DaTSCAN were included. We measured the volume of the neuromelanin-positive substantia nigra pars compacta (SNc volume) on NmMRI and measured the specific binding ratio (SBR) on DaTSCAN. The asymmetry index (AI) of the SNc volume and SBR were also calculated. We evaluated the relationship between the UPDRS III score and the SNc volume and SBR, respectively. Results The SNc volume showed a significant correlation with the SBR. The AIs of them also showed a significant correlation. Both the mean of the bilateral SBR and the mean of the bilateral SNc volume showed significant negative correlations with the UPDRS III score. However, the correlation between the SBR and the UPDRS III score was stronger than that between the SNc volume and the UPDRS III score. Conclusion Both NmMRI and DaTSCAN are helpful for PD diagnosis. However, we conclude that DaTSCAN is more suitable for the evaluation of the clinical motor severity and would be more useful for the management of PD patients than NmMRI.

Diagnostic performance of calcification-suppressed coronary CT angiography using rapid kilovolt-switching dual-energy CT.

OBJECTIVES: Multi-detector-row computed tomography angiography (MDCTA) plays an important role in the assessment of patients with suspected coronary artery disease. However, MDCTA tends to overestimate stenosis in calcified coronary artery lesions. The aim of our study was to evaluate the diagnostic performance of calcification-suppressed material density (MD) images produced by using a single-detector single-source dual-energy computed tomography (ssDECT). METHODS: We enrolled 67 patients with suspected or known coronary artery disease who underwent ssDECT with rapid kilovolt-switching (80 and 140 kVp). Coronary artery stenosis was evaluated on the basis of MD images and virtual monochromatic (VM) images. The diagnostic performance of the two methods for detecting coronary artery disease was compared with that of invasive coronary angiography as a reference standard. RESULTS: We evaluated 239 calcified segments. In all the segments, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for detecting significant stenosis were respectively 88%, 88%, 75%, 95% and 88% for the MD images, 91%, 71%, 56%, 95% and 77% for the VM images. PPV was significantly higher on the MD images than on the VM images (P < 0.0001). CONCLUSIONS: Calcification-suppressed MD images improved PPV and diagnostic performance for calcified coronary artery lesions. KEY POINTS: • Computed tomography angiography tends to overestimate stenosis in calcified coronary artery. • Dual-energy CT enables us to suppress calcification of coronary artery lesions. • Calcification-suppressed material density imaging reduces false-positive diagnosis of calcified lesion.

Reduction of metal artifacts due to dental hardware in computed tomography angiography: assessment of the utility of model-based iterative reconstruction.

PURPOSE: The aim of this study is to assess the value of adaptive statistical iterative reconstruction (ASIR) and model-based iterative reconstruction (MBIR) for reduction of metal artifacts due to dental hardware in carotid CT angiography (CTA). METHODS: Thirty-seven patients with dental hardware who underwent carotid CTA were included. CTA was performed with a GE Discovery CT750 HD scanner and reconstructed with filtered back projection (FBP), ASIR, and MBIR. We measured the standard deviation at the cervical segment of the internal carotid artery that was affected most by dental metal artifacts (SD1) and the standard deviation at the common carotid artery that was not affected by the artifact (SD2). We calculated the artifact index (AI) as follows: AI = [(SD1)2 - (SD2)2]1/2 and compared each AI for FBP, ASIR, and MBIR. Visual assessment of the internal carotid artery was also performed by two neuroradiologists using a five-point scale for each axial and reconstructed sagittal image. The inter-observer agreement was analyzed using weighted kappa analysis. RESULTS: MBIR significantly improved AI compared with FBP and ASIR (p < 0.001, each). We found no significant difference in AI between FBP and ASIR (p = 0.502). The visual score of MBIR was significantly better than those of FBP and ASIR (p < 0.001, each), whereas the scores of ASIR were the same as those of FBP. Kappa values indicated good inter-observer agreements in all reconstructed images (0.747-0.778). CONCLUSIONS: MBIR resulted in a significant reduction in artifact from dental hardware in carotid CTA.

Measurement of Myocardial Extracellular Volume Fraction From Iodine Density Images Using Single-Source, Dual-Energy Computed Tomography: A Feasibility Study.

OBJECTIVE: The aims of this study were to develop and validate an iodine density method for the quantification of myocardial extracellular volume (ECV) fraction using single-source, dual-energy computed tomography. METHODS: Extracellular volume measurements were carried out in 40 subjects (20 patients with heart failure, 20 control subjects) using single-source, dual-energy computed tomography. Subtraction-derived ECVs (subECVs) were computed by subtracting precontrast from delayed images. Iodine density-derived ECVs (iECVs) were calculated from iodine density images obtained from delayed images. Iodine density-derived ECVs were compared with reference subECVs. RESULTS: A strong correlation (r = 0.896, P < 0.0001) and a small bias (-0.06%) were determined between subECV and iECV with high interobserver concordances (0.915 and 0.906, respectively). Extracellular volume measurements in patients with heart failure were higher in both subECV and iECV compared with control subjects (34.6% [SD, 5.0%] vs 29.5% [SD, 3.6%], P = 0.001, for subECV; 34.9% [SD, 4.5%] vs 29.2% [SD, 2.6%], P < 0.0001, for iECV). CONCLUSIONS: Extracellular volume analysis using iodine density is a useful tool for the noninvasive quantification of ECV in myocardial diseases.

Proximal Bright Vessel Sign on Arterial Spin Labeling Magnetic Resonance Imaging in Acute Cardioembolic Cerebral Infarction.

BACKGROUND: The congestion of spin-labeled blood at large-vessel occlusion can present as hyperintense signals on perfusion magnetic resonance imaging with 3-dimensional pseudo-continuous arterial spin labeling (proximal bright vessel sign). The purpose of this study was to clarify the difference between proximal bright vessel sign and susceptibility vessel sign in acute cardioembolic cerebral infarction. METHODS: Forty-two patients with cardioembolic cerebral infarction in the anterior circulation territory underwent magnetic resonance imaging including diffusion-weighted imaging, 3-dimensional pseudo-continuous arterial spin labeling perfusion magnetic resonance imaging, T2*-weighted imaging, and 3-dimensional time-of-flight magnetic resonance angiography using a 3-T magnetic resonance scanner. Visual assessments of proximal bright vessel sign and the susceptibility vessel sign were performed by consensus of 2 experienced neuroradiologists. The relationship between these signs and the occlusion site of magnetic resonance angiography was also investigated. RESULTS: Among 42 patients with cardioembolic cerebral infarction, 24 patients showed proximal bright vessel sign (57.1%) and 25 showed susceptibility vessel sign (59.5%). There were 19 cases of proximal bright vessel sign and susceptibility vessel sign-clear, 12 cases of proximal bright vessel sign and susceptibility vessel sign-unclear, and 11 mismatched cases. Four out of 6 patients with proximal bright vessel sign-unclear and susceptibility vessel sign-clear showed distal middle cerebral artery occlusion, and 2 out of 5 patients with proximal bright vessel sign-clear and susceptibility vessel sign-unclear showed no occlusion on magnetic resonance angiography. CONCLUSIONS: Proximal bright vessel sign is almost compatible with susceptibility vessel sign in patients with cardioembolic cerebral infarction.

Carotid Plaque Evaluation Using Gemstone Spectral Imaging: Comparison with Magnetic Resonance Angiography.

BACKGROUND: The present study compared the applicability of computed tomography carotid plaque imaging using effective Z maps with gemstone spectral imaging (GSI) to that of magnetic resonance plaque imaging using 3-dimensional time-of-flight magnetic resonance angiography. METHODS: Stenosis was assessed in 18 carotid arteries of 14 patients, and the effective Z values of noncalcified carotid plaques were compared with the signal intensities of magnetic resonance angiography. RESULTS: It was found that the effective Z value of noncalcified carotid plaques was significantly lower for a group with high signal intensity than for a group with low signal intensity on magnetic resonance angiography (P <.001). The area under the receiver operating characteristic curve of effective Z values was .975, and the presumed cutoff effective Z value required to discriminate low and high intensity plaques on magnetic resonance angiography was 7.83. CONCLUSIONS: The effective Z value generated by GSI is a useful parameter to detect vulnerable carotid plaque materials.

Apparent diffusion coefficient (ADC) measurement in ovarian tumor: Effect of region-of-interest methods on ADC values and diagnostic ability.

PURPOSE: To investigate the difference in apparent diffusion coefficient (ADC) measurements of differently shaped regions of interest (ROIs) in ovarian tumors, and to investigate the diagnostic ability of differently shaped ROIs in differentiating benign from malignant ovarian tumors. MATERIALS AND METHODS: Fifty-four patients with ovarian tumors with a solid component were evaluated. The patients underwent magnetic resonance (MR) examinations including diffusion-weighted imaging using a 3.0T MR system. Two readers measured ADCs using four ROI methods: freehand, square, round, and five small round ROIs. The interclass correlation coefficient (ICC) and repeated-measures analysis of variance were used to assess their measurement reliability and to compare ADCs for each ROI method. Receiver operating characteristic curve analysis and unpaired t-test on each ROI were used to differentiate benign and malignant ovarian tumors and assess the diagnostic ability. RESULTS: All ROI methods except the square ROI (0.56) showed good or excellent correlations (0.70-0.91). Minimum and mean ADC values differed significantly between the ROIs (P < 0.05). When using the freehand ROI, the minimum and mean ADC values were the lowest and highest, respectively. The optimal cutoff minimum and mean ADC values of each ROI for differentiating benign and malignant tumors were 0.81-1.06 × 10(-3) mm(2) /s and 1.15-1.52 × 10(-3) mm(2) /s, respectively. The areas under the curve showed no significant differences among the ADCs in the different ROI methods (P > 0.05). Minimum and mean ADCs from all ROIs showed significant differences between benign and malignant tumors (P < 0.05). CONCLUSION: The ROI shape influences ADC values and the optimal cutoff ADC values for differentiating benign from malignant ovarian tumors.

Safety and Risk of Superselective Transcatheter Arterial Embolization for Acute Lower Gastrointestinal Hemorrhage with N-Butyl Cyanoacrylate: Angiographic and Colonoscopic Evaluation.

PURPOSE: To retrospectively evaluate the safety and risk of transcatheter arterial embolization (TAE) with N-butyl cyanoacrylate (NBCA) for urgent acute arterial bleeding control in the lower gastrointestinal tract by angiography and colonoscopy. MATERIALS AND METHODS: NBCA TAE was performed in 16 patients (mean age, 63.7 y) with lower gastrointestinal bleeding (diverticular hemorrhage, tumor bleeding, and intestinal tuberculosis). Angiographic evaluation was performed by counting the vasa recta filled with casts of NBCA and ethiodized oil (Lipiodol) after TAE. Patients were classified as follows: group Ia, with a single vas rectum with embolization of 1 branch (n = 6); group Ib, with a single vas rectum with embolization of ≥ 2 branches (n = 8); group II, with embolization of multiple vasa recta (n = 2). All patients underwent colonoscopy within 1 month, and ischemic complications (ulcer, scar, mucosal swelling, fibrinopurulent debris, and necrosis) were evaluated. RESULTS: The procedure was successful in all patients. No ischemic change was observed in any patients in group Ia and in two patients in group Ib. Ischemic changes were observed in six group Ib patients and both group II patients. Group Ib patients experienced ischemic complications that improved without treatment. One patient in group II underwent resection for intestinal perforation after embolization of three vasa recta. One patient in group II with sigmoid stricture with embolization of six vasa recta required prolonged hospitalization. CONCLUSIONS: NBCA embolization of ≥ 3 vasa recta can induce ischemic bowel damage requiring treatment. NBCA TAE of one vas rectum with ≥ 2 branches could also induce ischemic complications. However, these were silent and self-limited.

Correlation between neuromelanin-sensitive MR imaging and (123)I-FP-CIT SPECT in patients with parkinsonism.

INTRODUCTION: Neuromelanin-sensitive MR imaging (MRI) can visualize neuromelanin-containing neurons in the substantia nigra pars compacta (SNc), and its utility has been reported in the evaluation of parkinsonism. Conversely, dopamine transporter imaging by (123)I-N-v-fluoropropyl-2b-carbomethoxy-3b-(4-iodophenyl)nortropane (FP-CIT) SPECT (DaTSCAN) is now an established method for evaluating parkinsonism, detecting presynaptic dopamine neuronal dysfunction. Both methods can assist differentiating neurodegenerative and other forms of parkinsonism. However, to our knowledge, there have been no studies concerning a correlation between the two methods. The aim of this study was to assess the utility of neuromelanin-sensitive MRI for diagnosing parkinsonism by examining a correlation with DaTSCAN. METHODS: Twenty-three patients with parkinsonism who underwent both neuromelanin-sensitive MRI and DaTSCAN were included. We measured the neuromelanin-positive SNc region volume by manually contouring the high signal intensity region of the SNc on neuromelanin-sensitive MRI and measured the specific binding ratio (SBR) on DaTSCAN. The asymmetry index of neuromelanin-positive SNc volume and the asymmetry index of SBR were also calculated. RESULTS: The volume of the neuromelanin-positive SNc region showed significant correlation with specific binding ratio (SBR) (right P < .001, ρ = 0.78, left P < .001, ρ = 0.86). The asymmetry index of neuromelanin-positive SNc volume also showed significant correlations with the asymmetry index of SBR (P < .001, ρ = 0.73). CONCLUSIONS: Decrease of the high signal intensity region of the SNc on neuromelanin-sensitive MRI would indicate damage to the nigrostriatal dopaminergic function as well as loss of dopaminergic neurons. We conclude that neuromelanin-sensitive MRI is a useful diagnostic biomarker for parkinsonism.

The evaluation of cardiac tamponade risk in patients with pericardial effusion detected by non-gated chest CT.

BACKGROUND: Although pericardial effusion is often identified using non-gated chest computed tomography (CT), findings predictive of cardiac tamponade have not been adequately established. PURPOSE: To determine the findings predictive of clinical cardiac tamponade in patients with moderate to large pericardial effusion using non-gated chest CT. MATERIAL AND METHODS: We performed a retrospective analysis of 134 patients with moderate to large pericardial effusion who were identified from among 4581 patients who underwent non-gated chest CT. Cardiac structural changes, including right ventricular outflow tract (RVOT), were qualitatively evaluated. The inferior vena cava ratio with hepatic (IVCupp) and renal portions (IVClow) and effusion size were measured. The diagnostic performance of each structural change was calculated, and multivariate analysis was used to determine the predictors of cardiac tamponade. RESULTS: Of the 134 patients (mean age, 70.3 years; 64 men), 37 (28%) had cardiac tamponade. The sensitivity and specificity were 76% and 74% for RVOT compression; 87% and 84% for an IVClow ratio ≥0.77; and 60% and 77% for an effusion size ≥25.5 mm, respectively. Multivariate logistic regression analysis demonstrated that RVOT compression, an IVClow ratio ≥0.77, and an effusion size ≥25.5 mm were independent predictors of cardiac tamponade. The combination of these three CT findings had a sensitivity, specificity, and accuracy of 81%, 95%, and 91%, respectively. CONCLUSION: In patients with moderate to large pericardial effusion, non-gated chest CT provides additional information for predicting cardiac tamponade.

Significance of combined use of MRI and perfusion SPECT for evaluation of multiple system atrophy, cerebellar type.

BACKGROUND: Multiple system atrophy, cerebellar type (MSA-C) sometimes shows asymmetrical findings on magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT). PURPOSE: To assess the frequency and clinical significance of asymmetrical MRI and (99m)Tc-ethyl cysteinate dimer perfusion (ECD) SPECT findings of the cerebellum, middle cerebellar peduncle (MCP), and pons in MSA-C patients. MATERIAL AND METHODS: We retrospectively reviewed 28 patients with MSA-C who underwent MRI and (99m)Tc-ECD SPECT and evaluated laterality of atrophy and signal changes on MRI, and laterality of perfusion on (99m)Tc-ECD SPECT transversely and longitudinally. RESULTS: Laterality was identified for 64%, 61%, and 21% of atrophy in the cerebellum, MCP, and pons, respectively, on MRI and for 71% of atrophy in the cerebellum on perfusion SPECT. Concerning comparisons between the latest MRI and SPECT findings, laterality of cerebellar/MCP atrophy on MRI and decreased cerebellar perfusion on SPECT was matched in 57%, mismatched in 11%, and absent in 25% of patients. On past images, MRI and SPECT showed matched laterality in 33%, mismatched laterality in 27%, no laterality in 13%, and SPECT precedent laterality in 27% of patients. Including the latest and past images, asymmetrical changes were observed in 75% of patients. We could not identify any correlation between laterality of image findings and cerebellar symptoms in most patients. CONCLUSION: Asymmetrical changes on MRI and perfusion SPECT are common in MSA-C patients. Perfusion SPECT is useful for diagnosing MSA-C in the early stages from a functional perspective.

The Effectiveness of Non-ECG-Gated Contrast-Enhanced Computed Tomography for the Diagnosis of Non-ST Segment Elevation Acute Coronary Syndrome.

Non-ST segment elevation acute coronary syndrome (NSTE-ACS) can be difficult to diagnose accurately, especially in the hyper-acute phase. Non-ECG-gated contrast-enhanced computed tomography (non-ECG-gated CE-CT) has been used in many institutions for screening acute chest pain. Although early defects (EDs) observed in non-ECG-gated CE-CT have been reported as a sign of acute myocardial ischemia, the precise diagnostic value of this sign for acute coronary syndrome has not been fully elucidated. We investigated the usefulness of non-ECG-gated CE-CT for the diagnosis of NSTE-ACS. We retrospectively reviewed 556 patients who were hospitalized for acute-onset chest pain and who underwent emergent coronary angiography. Non-ECG-gated CE-CT was performed in 23 of these patients. Two readers independently analyzed CT images using a 5-point scale. Of the 23 patients, 13 were diagnosed with NSTE-ACS. The remaining 10 patients were diagnosed with other conditions. The sensitivity, specificity, positive predictive value, and negative predictive value, respectively, of EDs on non-ECG-gated CE-CT to detect NSTE-ACS were 84.6%, 90%, 91.7%, and 81.8%. The identification of EDs was consistent between the two readers. Non-ECG-gated CE-CT may be useful not only to triage patients with chest pain by ruling out other conditions, but also to accurately diagnose NSTE-ACS.

Accuracy of semiquantitative dynamic contrast-enhanced MRI for differentiating type II from type I endometrial carcinoma.

PURPOSE: To investigate type II endometrial carcinoma characterization using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and evaluate the diagnostic accuracy of semiquantitative DCE-MRI in differentiating type II from type I tumors. MATERIALS AND METHODS: Seventy-seven patients with endometrial carcinoma were retrospectively evaluated using 3T DCE-MRI. The maximum absolute enhancement of signal intensity (SImax), maximum relative enhancement (SIrel), wash-in rate (WIR), and the SImax/SI (piriformis) ratio were analyzed. To differentiate type I from type II tumors, optimal threshold criteria were established. The Mann-Whitney U-test was used for statistical comparison and receiver operating characteristic curve analysis was used to determine optimal cutoff values. RESULTS: The SIrel (P < 0.001), WIR (P < 0.0001), and SImax/SI (piriformis) ratio (P < 0.0001), but not SImax, differed significantly between type I and type II carcinomas. Cutoff values of SIrel ≥58.8, WIR ≥37.0, and SImax/SI (piriformis) ratio ≥1.55 had sensitivities of 93%, 93%, and 67%, specificities of 60%, 60%, and 79%, accuracies of 66%, 66%, and 67%, respectively, for predicting type II endometrial carcinoma. CONCLUSION: Endometrial carcinoma with strong (high level) enhancement on DCE-MRI is suggestive of type II endometrial carcinoma. Semiquantitative evaluation of DCE-MRI may be useful for differentiating type II from type I tumors.

Correlation of apparent diffusion coefficient value with prognostic parameters of endometrioid carcinoma.

PURPOSE: To correlate the apparent diffusion coefficient (ADC) of endometrioid carcinoma with histological tumor grade and degree of myometrial invasion. MATERIALS AND METHODS: 3T diffusion-weighted (DW) magnetic resonance (MR) images of 63 patients were retrospectively reviewed. Two readers measured tumor ADC according to a freehand region of interest (ROI) and a round ROI. Mean and minimum ADCs were correlated with prognostic parameters. RESULTS: The minimum ADC was 0.64 × 10(-3) mm(2)/s for grade 1 (G1, n = 42), 0.62 for grade 2 (G2, n = 14), 0.46 for grade 3 (G3, n = 7) on freehand ROI. There were significant differences between G1 and G3 (P = 0.007), and G2 and G3 (P = 0.038). No significant correlation was found between tumor grade and mean ADC (0.85 for G1, 0.82 for G2, and 0.72 for G3, P = 0.166). The minimum ADC was significantly lower for patients with deep (n = 21, 0.54) than for those with superficial (n = 39, 0.65) myometrial invasion. Conversely, mean ADC did not differ significantly (0.84 for superficial and 0.78 for deep myometrial invasion, P = 0.081). The same tendency was shown on round ROI. CONCLUSION: The minimum ADC correlates with prognostic parameters of endometrial carcinoma more strongly than mean ADC. Lower minimum ADC is associated with higher histological tumor grade and higher degree of myometrial invasion.

Usefulness of R2* maps generated by iterative decomposition of water and fat with echo asymmetry and least-squares estimation quantitation sequence for cerebral artery dissection.

INTRODUCTION: Acute intramural hematoma resulting from cerebral artery dissection is usually visualized as a region of intermediate signal intensity on T1-weighted images (WI). This often causes problems with distinguishing acute atheromatous lesions from surrounding parenchyma and dissection. The present study aimed to determine whether or not R2* maps generated by the iterative decomposition of water and fat with echo asymmetry and least-squares estimation quantitation sequence (IDEAL IQ) can distinguish cerebral artery dissection more effectively than three-dimensional variable refocusing flip angle TSE T1WI (T1-CUBE) and T2*WI. METHODS: We reviewed data from nine patients with arterial dissection who were assessed by MR images including R2* maps, T2*WI, T1-CUBE, and 3D time-of-flight (TOF)-MRA. We visually assessed intramural hematomas in each patient as positive (clearly visible susceptibility effect reflecting intramural hematoma as hyperintensity on R2* map and hypointensity on T2*WI), negative (absent intramural hematoma), equivocal (difficult to distinguish between intramural hematoma and other paramagnetic substances such as veins, vessel wall calcification, or hemorrhage) and not evaluable (difficult to determine intramural hematoma due to susceptibility artifacts arising from skull base). RESULTS: Eight of nine patients were assessed during the acute phase. Lesions in all eight patients were positive for intramural hematoma corresponding to dissection sites on R2* maps, while two lesions were positive on T2*WI and three lesions showed high-intensity on T1-CUBE reflected intramural hematoma during the acute phase. CONCLUSION: R2* maps generated using IDEAL IQ can detect acute intramural hematoma associated with cerebral artery dissection more effectively than T2*WI and earlier than T1-CUBE.

Assessment of carotid plaque composition using fast-kV switching dual-energy CT with gemstone detector: comparison with extracorporeal and virtual histology-intravascular ultrasound.

INTRODUCTION: The present study compares the applicability of CT carotid plaque imaging using effective Z maps using gemstone spectral imaging (GSI) with that of conventional extracorporeal carotid ultrasound (US) and virtual histology-intravascular ultrasound (VH-IVUS). METHODS: We assessed stenosis in 31 carotid arteries of 30 patients. All patients underwent carotid CTA using GSI (Discovery CT750 HD, GE Healthcare). US and IVUS were examined with 25 and 8 vessels, respectively. We compared the effective Z values at noncalcified carotid plaque with the plaque components identified by US. We defined the plaque with low or low to iso intensity on US as vulnerable plaque and the plaque with iso, iso to high, and high intensity on US as stable plaque. We also performed visual assessment of color-coded effective Z maps in comparison with VH-IVUS and compared effective Z values with plaque components generated by VH-IVUS. RESULTS: The effective Z values at noncalcified carotid plaque were significantly lower for a group with vulnerable plaque, than with stable plaque on US (p < 0.05). Receiver operating curve analysis showed that AUC of effective Z values was 0.882 concerning the differentiation of these two groups on US. The interpretation of color-coded effective Z maps was essentially compatible with that of VH-IVUS for carotid plaque in all vessels. Effective Z values at noncalcified plaque showed significant negative correlation with the areas of fibro-fatty components generated by VH-IVUS (ρ = -0.874, p < 0.05). CONCLUSION: Effective Z maps generated by GSI can detect vulnerable carotid plaque materials.