Intracranial aneurysms treated with stent-assisted coil embolization: evaluation with four-dimensional ultrashort-TE MR angiography.

OBJECTIVES: As a novel follow-up method for intracranial aneurysms treated with stent-assisted coil embolization (SACE), we developed four-dimensional magnetic resonance angiography (MRA) with minimized acoustic noise utilizing ultrashort-echo time (4D mUTE-MRA). We aimed to assess whether 4D mUTE-MRA is useful for the evaluation of intracranial aneurysms treated with SACE. METHODS: This study included 31 consecutive patients with intracranial aneurysm treated with SACE who underwent 4D mUTE-MRA at 3 T and digital subtraction angiography (DSA). For 4D mUTE-MRA, five dynamic MRA images with a spatial resolution of 0.5 × 0.5 × 0.5 mm3 were obtained every 200 ms. Two readers independently reviewed the 4D mUTE-MRA images to evaluate the aneurysm occlusion status (total occlusion, residual neck, and residual aneurysm) and the flow in the stent using a 4-point scale (from 1 [not visible] to 4 [excellent]). The interobserver and intermodality agreement was assessed using κ statistics. RESULTS: On DSA images, 10 aneurysms were classified as total occlusion, 14 as residual neck, and 7 as residual aneurysm. In terms of aneurysm occlusion status, the intermodality and interobserver agreement was excellent (κ = 0.92 and κ = 0.96, respectively). For the flow in the stents on 4D mUTE-MRA, the mean score was significantly higher for single stents than multiple stents (p < .001) and for open-cell type stents than closed-cell type (p < .01). CONCLUSIONS: 4D mUTE-MRA is a useful tool with a high spatial and temporal resolution for the evaluation of intracranial aneurysms treated with SACE. KEY POINTS: • In the evaluation of intracranial aneurysms treated with SACE on 4D mUTE-MRA and DSA, the intermodality and interobserver agreement in aneurysm occlusion status was excellent. • 4D mUTE-MRA shows good to excellent visualization of flow in the stents, especially for cases treated with a single or open-cell stent. • 4D mUTE-MRA can provide hemodynamic information related to embolized aneurysms and the distal arteries to stented parent arteries.

Hybrid deep-learning-based denoising method for compressed sensing in pituitary MRI: comparison with the conventional wavelet-based denoising method.

OBJECTIVES: This study aimed to evaluate the efficacy of a combined wavelet and deep-learning reconstruction (DLR) method for under-sampled pituitary MRI. METHODS: This retrospective study included 28 consecutive patients who underwent under-sampled pituitary T2-weighted images (T2WI). Images were reconstructed using either the conventional wavelet denoising method (wavelet method) or the wavelet and DLR methods combined (hybrid DLR method) at five denoising levels. The signal-to-noise ratio (SNR) of the CSF, hypothalamic, and pituitary images and the contrast between structures were compared between the two image types. Noise quality, contrast, sharpness, artifacts, and overall image quality were evaluated by two board-certified radiologists. The quantitative and the qualitative analyses were performed with robust two-way repeated analyses of variance. RESULTS: Using the hybrid DLR method, the SNR of the CSF progressively increased as denoising levels increased. By contrast, with the wavelet method, the SNR of the CSF, hypothalamus, and pituitary did not increase at higher denoising levels. There was a significant main effect of denoising methods (p < 0.001) and denoising levels (p < 0.001), and an interaction between denoising methods and denoising levels (p < 0.001). For all five qualitative scores, there was a significant main effect of denoising methods (p < 0.001) and an interaction between denoising methods and denoising levels (p < 0.001). CONCLUSIONS: The hybrid DLR method can provide higher image quality for T2WI of the pituitary with compressed sensing (CS) than the wavelet method alone, especially at higher denoising levels. KEY POINTS: • The signal-to-noise ratios of cerebrospinal fluid progressively increased with the hybrid DLR method, with an increase in the denoising level for cerebrospinal fluid in pituitary T2WI with CS. • The signal-to-noise ratios of cerebrospinal fluid using the conventional wavelet method did not increase at higher denoising levels. • All qualitative scores of hybrid deep-learning reconstructions at all denoising levels were higher than those for the wavelet denoising method.

A preliminary study of deep learning-based reconstruction specialized for denoising in high-frequency domain: usefulness in high-resolution three-dimensional magnetic resonance cisternography of the cerebellopontine angle.

PURPOSE: Deep learning-based reconstruction (DLR) has been developed to reduce image noise and increase the signal-to-noise ratio (SNR). We aimed to evaluate the efficacy of DLR for high spatial resolution (HR)-MR cisternography. METHODS: This retrospective study included 35 patients who underwent HR-MR cisternography. The images were reconstructed with or without DLR. The SNRs of the CSF and pons, contrast of the CSF and pons, and sharpness of the normal-side trigeminal nerve using full width at half maximum (FWHM) were compared between the two image types. Noise quality, sharpness, artifacts, and overall image quality of these two types of images were qualitatively scored. RESULTS: The SNRs of the CSF and pons were significantly higher with DLR than without DLR (CSF 21.81 ± 7.60 vs. 15.33 ± 4.03, p < 0.001; pons 5.96 ± 1.38 vs. 3.99 ± 0.48, p < 0.001). There were no significant differences in the contrast of the CSF and pons (p = 0.225) and sharpness of the normal-side trigeminal nerve using FWHM (p = 0.185) without and with DLR, respectively. Noise quality and the overall image quality were significantly higher with DLR than without DLR (noise quality 3.95 ± 0.19 vs. 2.53 ± 0.44, p < 0.001; overall image quality 3.97 ± 0.17 vs. 2.97 ± 0.12, p < 0.001). There were no significant differences in sharpness (p = 0.371) and artifacts (p = 1) without and with DLR. CONCLUSION: DLR can improve the image quality of HR-MR cisternography by reducing image noise without sacrificing contrast or sharpness.

Myocardial extracellular volume quantification in cardiac CT: comparison of the effects of two different iterative reconstruction algorithms with MRI as a reference standard.

OBJECTIVES: To compare the effects of hybrid iterative reconstruction (HIR) and model-based iterative reconstruction (MBIR) that incorporates a beam-hardening model for myocardial extracellular volume (ECV) quantification by cardiac CT using MRI as a reference standard. METHODS: In this retrospective study, a total of 34 patients were evaluated using cardiac CT and MRI. Paired CT image sets were created using HIR and MBIR with a beam-hardening model. We calculated mean absolute differences and correlations between the global mid-ventricular ECV derived from CT and MRI via Pearson correlation analysis. In addition, we performed qualitative analysis of image noise and beam-hardening artifacts on postcontrast images using a four-point scale: 1 = extensive, 2 = strong, 3 = mild, and 4 = minimal. RESULTS: The mean absolute difference between the ECV derived from CT and MRI for MBIR was significantly smaller than that for HIR (MBIR 3.74 ± 3.59%; HIR 4.95 ± 3.48%, p = 0.034). MBIR improved the correlation between the ECV derived from CT and MRI when compared with HIR (MBIR, r = 0.60, p < 0.001; HIR, r = 0.47, p = 0.006). In qualitative analysis, MBIR significantly reduced image noise and beam-hardening artifacts when compared with HIR ([image noise, MBIR 3.4 ± 0.7; HIR 2.1 ± 0.8, p < 0.001], [beam-hardening artifacts, MBIR 3.8 ± 0.4; HIR 2.6 ± 1.0, p < 0.001]). CONCLUSIONS: MBIR with a beam-hardening model effectively reduced image noise and beam-hardening artifacts and improved myocardial ECV quantification when compared with HIR using MRI as a reference standard. KEY POINTS: • MBIR with a beam-hardening model effectively reduced image noise and beam-hardening artifacts. • The mean absolute difference between the global mid-ventricular ECV derived from CT and MRI for MBIR was significantly smaller than that for conventional HIR. • MBIR provided more accurate myocardial CT number and improved ECV quantification when compared with HIR.

Successful Treatment of Intrahepatic Cholangiocarcinoma With Liver/Lung Metastasis and Peritoneal Dissemination After Liver Resection.

BACKGROUND/AIM: Intrahepatic cholangiocarcinoma (ICC) is increasing in incidence and has a poor prognosis. CASE REPORT: A 79-year-old woman with two liver tumors was referred to our institution. The tumors demonstrated irregular margins and continuous peripheral enhancement. She had a good liver function and an elevated CA19-9 level. Extended left hepatectomy, and partial hepatectomy was performed. The patient was diagnosed with poorly differentiated ICC. Two lung metastases, one liver metastasis, and localized intraperitoneal dissemination occurred 19, 24, and 32 months after the initial hepatectomy. The lung metastases were treated with computed tomography-guided radiofrequency ablation approximately after one year of observation. The liver metastasis was resected immediately. The peritoneal dissemination was removed entirely after effective 3-month chemotherapy using gemcitabine and S-1. The patient is alive with no tumor 44 months after the first surgery. CONCLUSION: Multidisciplinary treatment considering a metastatic site and tumor malignancy might be effective for patients with ICC who have multiple recurrences.

Assessment of cardiac implantable electric device lead perforation using a metal artifact reduction algorithm in cardiac computed tomography.

PURPOSE: CT is considered the non-invasive gold standard for evaluating cardiac implantable electronic devices (CIEDs) lead perforation, but metal artifacts caused by the lead tip affect the image quality and make a definitive diagnosis challenging. We compared the performances of the metal artifact reduction (MAR) algorithm and the conventional algorithm for identification of the right ventricular (RV) lead tip position in cardiac CT studies of patients with CIEDs. METHOD: Forty-seven consecutive patients (26 men; age 70.3 ±â€¯15.4 years) with CIEDs underwent cardiac CT. Using the conventional and MAR algorithm, two image reconstructions were performed for each scan. We calculated the artifact index (AI) to assess the quantitative capability of the MAR algorithm for artifact reduction and visually assessed the RV lead tip position on both images as follows: non-perforation, perforation, and equivocal. RESULTS: The mean AIs were significantly lower with the MAR algorithm than with the conventional algorithm (96.7 ±â€¯40.1 HU vs. 284.6 ±â€¯134.1 HU, P < 0.001). Thirteen (27.7 %) patients were diagnosed as equivocal using the conventional algorithm but were diagnosed with perforation (2 patients) and non-perforation (11 patients) using the MAR algorithm (equivocal rate: 27.7 % vs. 0%, P < 0.001). Using the MAR algorithm, all cases were diagnosed with perforation (6 patients, 12.8 %) or non-perforation (41 patients, 87.2 %). CONCLUSIONS: The MAR algorithm effectively reduced metal artifacts and allowed us to diagnose the presence or absence of perforation in all cases, whereas definitive diagnosis was difficult with the use of conventional algorithm in 27.7 % of cases.

Diffusion-weighted imaging of primary brain lymphomas: effect of ADC value and signal intensity of T2-weighted imaging.

The purpose of this study was to determine whether apparent diffusion coefficient (ADC) value and T2 signal intensity (SI) in primary brain lymphomas affect their SI on diffusion-weighted images (DWI). On DWI of 16 brain lesions of 16 patients, 9 (56.2%) were hyperintense (grade-3), 4 (25%) partially hyperintense (grade-2) and 3 (18.8%) isointense (grade-1). The mean ADC value of grade-3 lesions was significantly lower than of grade-1 lesions (p=0.028). The grade-1 lesions had ADC values of more than 0.8 and contrast-to-noise ratios of less than 18 on T2-weighted images. Their ADC value and T2 signal intensity affect their SI on DWI.

Detection of hemorrhagic hypointense foci in the brain on susceptibility-weighted imaging clinical and phantom studies.

RATIONALE AND OBJECTIVES: To determine the sensitivity of susceptibility-weighted imaging (SWI) for depicting hemorrhagic hypointense foci of the brain in comparison with gradient-recalled echo (GRE)- and GRE-type single-shot echo-planar imaging (GREI, GRE-EPI), and to assess the basic characteristics of the susceptibility effect by using a phantom. MATERIALS AND METHODS: We prospectively examined 16 patients (9 males, 7 females, aged 10-74 years, mean 43 years) with hypointense foci using SWI, GREI, and GRE-EPI at a 1.5-T magnetic resonance (MR) unit. The contrast-to-noise ratio (CNR), sensitivity to small hypointese foci, and artifacts were evaluated. To assess the basic characteristics of SWI, we performed a phantom study using different concentrations of superparamagnetic iron oxide (SPIO). RESULTS: The CNR of lesions was significantly greater for SWI than the other images (P < .0001). SWI detected the greatest number of small hypointense foci, even in the near-skull-base and infratentorial regions. Quantitative and qualitative analyses in our clinical and phantom studies demonstrated that the degree of artifacts was similar with SWI and GREI. CONCLUSION: SWI was best for detecting small hemorrhagic hypointense foci. Artifacts of SWI were similar to GREI.

Pathological roles of advanced glycation end product receptors SR-A and CD36.

The pathological significance of advanced glycation end product (AGE)-modified proteins deposited in several lesions is generally accounted for by their cellular interaction via the AGE receptors and subsequent acceleration of the inflammatory process. In this study, we focused on two AGE receptors-specifically, the role of SR-A in pathogenesis of diabetic nephropathy and the role of CD36 in AGE-induced downregulation of leptin by adipocytes. In terms of SR-A, diabetic wild-type mice exhibited increased urinary albumin excretion, glomerular hypertrophy, and mesangial matrix expansion, whereas SR-A-knockout mice showed reduced glomerular size and mesangial matrix area. In these diabetic SR-A-knockout mice, the number of macrophages that infiltrated into glomeruli was remarkably reduced (P < 0.05), suggesting that SR-A-dependent glomerular migration of macrophages plays an important role in the pathogenesis of diabetic nephropathy. In terms of CD36, incubation of glycolaldehyde-modified bovine serum albumin (GA-BSA) with 3T3-L1 adipocytes reduced leptin secretion by these cells. The binding of GA-BSA to these cells and subsequent endocytic degradation were effectively inhibited by a neutralizing anti-CD36 antibody. AGE-induced downregulation of leptin was protected by N-acetyl-cysteine, an antioxidant. These results indicate that the interaction of AGE ligands with 3T3-L1 adipocytes via CD36 induces oxidative stress and leads to inhibition of leptin expression by these cells, suggesting a potential link of this phenomenon to exacerbation of the insulin sensitivity in metabolic syndrome.

Spinal imaging features in Japanese patients with Marfan syndrome: a case-control study.

PURPOSE: The purpose of our study was to evaluate the morphology of the lumbosacral spine, i.e. the dura and vertebral body shape, of Japanese patients with Marfan syndrome (MFS) by comparing it with sex- and age-matched controls. MATERIALS AND METHODS: Spinal MR or CT images of 32 MFS patients and 32 controls were retrospectively reviewed. The anteroposterior dural sac diameter (DSD), anteroposterior vertebral body diameter (VBD), and vertebral body height (VBH) were measured from L1 to S1 levels and the dural sac ratio [DSR = (DSD/VBD)] and vertebral body aspect ratio [VAR = (VBH/VBD)] were calculated. RESULTS: At each level, mean DSD and DSR were significantly higher in MFS patients; VBD was not. The cutoff values for DSR to differentiate between MFS patients and the controls were 0.59, 0.46, 0.42, 0.45, 0.47, and 0.47 from the level of L1 to S1. At a sensitivity of 93.8 % and a specificity of 84.4 % the cutoff value at S1 was most diagnostic. In MFS patients VAR was significantly higher at L3 and L4. CONCLUSION: Our cutoff value for DSR >0.47 at S1 may help to identify MFS in the Japanese population. A square-like appearance of the L3 and L4 vertebral bodies is a supplementary finding in MFS patients.

Incidence and severity of acute adverse reactions to four different gadolinium-based MR contrast agents.

PURPOSE: Differences in acute adverse reactions to different gadolinium (Gd)-based contrast agents have not been thoroughly evaluated. We investigated the relationships among the incidence and severity of acute adverse reactions, backgrounds of patients, and 4 types of different Gd-based contrast agents (gadopentetate dimeglumine, gadoteridol, gadoterate meglumine, and gadoxetate disodium). MATERIALS AND METHODS: We retrospectively reviewed the radiological records of 10,595 consecutive patients (4,343 female; 6,252 male; mean age, 63.8 ± 14.0 years) who underwent contrast-enhanced magnetic resonance imaging between August 2006 and March 2011. Adverse reactions were classified as mild, moderate, and severe according to the definition of the American College of Radiology. The incidence of adverse reactions were compared on the basis of clinical characteristics and type, dose, and delivery methods of contrast agents by univariate and multivariate logistic regression analyses. RESULTS: The incidence of overall reactions was 0.45% (48/10,595); 45 reactions were mild and three were moderate. No severe reactions were observed. Although the incidence of adverse reactions did not differ significantly between male and female patients, younger individuals were at higher risk for acute adverse reactions. The contrast injection rate and contrast dose were not significantly related to the incidence of adverse reactions. The incidence of adverse reactions was significantly higher for gadoxetate disodium (0.82%) than gadopentetate dimeglumine (0.43%). CONCLUSION: The incidence of acute adverse reactions elicited by Gd-based contrast agents injection was only 0.45%. Younger age was a risk factor for acute reactions. All 4 agents were found to be safe, although gadoxetate disodium showed a relatively higher incidence of adverse reactions.

Can sufficient preoperative information of intracranial aneurysms be obtained by using 320-row detector CT angiography alone?

PURPOSE: To determine whether sufficient pre-surgical treatment information of unruptured intracranial aneurysms can be obtained by using 320-row detector CT angiography (CTA) alone. MATERIALS AND METHODS: We enrolled 40 consecutive patients with unruptured intracranial aneurysms. All patients were prospectively conducted to perform 320-detector CTA as the only preoperative modality. Two blinded readers independently assessed CTA images. Interobserver agreement and the agreement between CTA and surgical findings were determined by calculating the κ coefficient. The referring neurosurgeons judged the usefulness of the information provided by CTA for treatment decisions. RESULTS: All patients had surgery without intraarterial digital subtraction angiography. Agreement between CTA and surgical findings was excellent for the aneurysm location (κ = 1.0) and good for the shape (κ = 0.71), neck (κ = 0.74) and its relationship with adjacent branches (κ = 0.71). Information obtained with 320-detector CTA was highly useful for surgical treatment in 37 of 40 (93 %) patients, although small perforators deriving from the aneurysm in 2 cases were not fully visualized on CTA images. CONCLUSION: In most patients with unruptured intracranial aneurysms, sufficient pre-surgical treatment information can be obtained by using 320-detector CTA alone.

13C MR imaging of methionine-rich gliomas at 4.7T: a pilot study.

We explored the feasibility of using carbon-13 ((13)C) magnetic resonance imaging ((13)C-MRI) to depict (13)C-labeled methionine-enriched gliomas at 4.7 tesla. We transplanted 2 types of glioma cells separately to 2 subcutaneous tissue sites on the backs of mice weighing 15 to 20 g. After confirming tumor growth, we used (13)C-MRI and (1)H-MRI to scan 4 mice that had been administered (13)C-labeled methionine and 2 control mice. (13)C-MRI of all 4 transplanted mice administered with (13)C-labeled methionine revealed 2 areas of hyperintensity that corresponded to the tumor sites on (1)H-MR images, but no such areas were visualized in transplanted controls. Our data suggest that (13)C-MRI can show the accumulation of (13)C-labeled tracer by gliomas.

Type 1 perimedullary arteriovenous fistula with subarachnoid hemorrhage: utility of contrast-enhanced 3D gradient-echo technique.

PURPOSE: In patients with perimedullary arteriovenous fistula (AVF) with subarachnoid hemorrhage (SAH), knowledge of lesion location is necessary to select the appropriate approach for catheter spinal angiography. We evaluated the utility of 3-dimensional (3D) fast imaging with steady-state precession (FISP) sequence for detecting type 1 perimedullary AVF with SAH. MATERIALS AND METHODS: We evaluated 4 patients (2 men, 2 women, aged 53 to 68 years, mean age, 59.25 years) with type 1 perimedullary AVF who presented with SAH and underwent conventional spin-echo MR and contrast-enhanced 3D FISP imaging. Two neuroradiologists assessed detection of vascular lesions and delineation of their relationships to the adjacent vessels. Catheter angiography was used as the reference standard and compared with the MR findings. RESULTS: Perimedullary AVF was located at the medullocervical junction in 2 patients, cervical spine in one, and thoracic spine in one. For all patients, use of contrast-enhanced 3D FISP in addition to conventional MR imaging improved lesion detection and delineation of the relationship between the lesion and surrounding vessels. CONCLUSION: Contrast-enhanced 3D FISP imaging was useful for detecting and delineating type 1 perimedullary AVF with SAH.

Multi-tensor tractography of the motor pathway at 3T: a volunteer study.

Conventional single-tensor tractography cannot depict the entire motor tract of the corticospinal tract because of fiber-crossing and other factors. Using a 3-tesla magnetic resonance (MR) unit, we compared single- and multi-tensor methods for the tract ratio of the 5 major components of the motor pathway, the lower extremity, trunk, hand, face, and tongue, in 5 healthy volunteers. Multi-tensor tractography is better than single-tensor tractography at 3T in depicting more fibers of non-trunk areas from the primary motor cortex.

Assessment of cerebral perfusion from bypass arteries using magnetic resonance regional perfusion imaging in patients with moyamoya disease.

PURPOSE: The purpose of this study was to evaluate whether cerebral perfusion from bypassed arteries can be demonstrated on regional perfusion imaging (RPI) using arterial spin labeling. We then compared cerebral perfusion on RPI and digital subtraction angiography (DSA) in moyamoya patients who underwent extracranial-intracranial bypass surgery. MATERIALS AND METHODS: We performed RPI using a 3-T magnetic resonance scanner and DSA studies in 11 moyamoya patients treated by bypass surgery. For RPI we placed a selective labeling slab on the bypassed external carotid artery. Two neuroradiologists determined the extent and location of the cerebral perfusion from bypass arteries in the middle cerebral artery territories on RPI and DSA. Kappa analysis was used to assess the interobserver agreement with respect to the extent and location of the cerebral perfusion and to evaluate the intermodality agreement between RPI and DSA. RESULTS: Interobserver agreement for the extent of cerebral perfusion on RPI was very good (kappa=0.89), with excellent location (kappa=1.00). Intermodality agreement for the extent of perfusion was very good (kappa=0.89), with good location (kappa=0.74). CONCLUSION: RPI is useful for evaluating cerebral perfusion from bypass arteries in moyamoya patients.

Differentiation of common large sellar-suprasellar masses effect of artificial neural network on radiologists' diagnosis performance.

RATIONALE AND OBJECTIVES: When pituitary adenoma, craniopharyngioma, and Rathke's cleft cyst grow in the sellar and suprasellar region, it is often difficult to differentiate among these three lesions on magnetic resonance (MR) images. The purpose of this study was to apply an artificial neural network (ANN) for differential diagnosis among these three lesions with MR images and retrospectively evaluate the effect of ANN output on radiologists' performance. MATERIALS AND METHODS: Forty-three patients with sellar-suprasellar masses were studied. The ANN was designed to differentiate among pituitary adenoma, craniopharyngioma, and Rathke's cleft cyst by using patients' ages and nine MR image findings obtained by three neuroradiologists using a subjective rating scale. In the observer performance test, MR images were viewed by nine radiologists, including four neuroradiologists and five general radiologists, first without and then with ANN output. The radiologists' performance was evaluated using receiver-operating characteristic analysis with a continuous rating scale. RESULTS: The ANN showed high performance in differentiation among the three lesions (area under the receiver-operating characteristic curve, 0.990). The average area under the curve for all radiologists for differentiation among the three lesions increased significantly from 0.910 to 0.985 (P = .0024) when they used the computer output. Areas under the curves for the general radiologists and neuroradiologists increased from 0.876 to 0.983 (P = .0083) and from 0.952 to 0.989 (P = .038), respectively. CONCLUSION: In diagnostic performance for differentiation among pituitary macroadenoma, craniopharyngioma, and Rathke's cleft cyst with MR imaging, the ANN resulted in parity between neuroradiologists and general radiologists.

Diffusion-weighted imaging in ischemic stroke: effect of display method on observers' diagnostic performance.

RATIONALE AND OBJECTIVES: When evaluating ischemic stroke on diffusion-weighted magnetic resonance imaging (DWI), the display method has not been investigated. The purpose of this study was to determine whether standardization of the display method for DWI affects observers' diagnostic performance in detecting ischemic stroke on DWI. MATERIALS AND METHODS: Twenty-six observers evaluated 40 DWI studies in 20 patients with acute (< 6 hours) middle cerebral arterial strokes and 20 controls for the presence of hyperintense lesions in 10 areas using the Alberta Stroke Programme Early CT Score (ASPECTS) system and one area in the corona radiata using a modified version of the ASPECTS system (ASPECTS-DWI). The images were reviewed using a standardized display method (SDM) and a conventional display method (CDM). The reading time was recorded for each session. The observers' performance was evaluated with receiver-operating characteristic analysis. RESULTS: In all observers with ASPECTS-DWI scores of < or = 8 points, the value of the mean average area under the receiver-operating characteristic curve was slightly higher for the SDM than the CDM, but the difference was not statistically significant. In the insular ribbon, diagnostic accuracy was significantly higher with the SDM than the CDM (P = .036). In the other locations, there were no significant differences. With the SDM, the mean reading time was reduced by 7.5 seconds (P = .024). CONCLUSION: The SDM improved diagnostic accuracy for the insular ribbon and shortened the reading time, although it did not improve observers' performance with the ASPECTS-DWI system.

Diffusion tensor tractography in the head-and-neck region using a clinical 3-T MR scanner.

RATIONALE AND OBJECTIVES: Diffusion tensor tractography (DTT) for neural fibers of the head-and-neck region at 3T has not been reported. The purpose of this study was to evaluate the feasibility of using DTT for visualizing neural fibers in the head-and-neck region at 3T and to explore the use of this method in patients with head-and-neck mass lesions. MATERIALS AND METHODS: Using a 3T scanner, we obtained magnetic resonance images of the head and neck region in 5 healthy volunteers and 5 patients with head and neck mass lesions. All subjects underwent anatomic T1-weighted and diffusion-tensor imaging using a sequence with six motion-probing gradient orientations, a b value of 800 second/mm(2), and a 128 x 128 pixel matrix. Fiber tracking was with the continuous tracking method. Different postprocessing parameters were investigated to optimize fiber density detection and minimize noise. In five patients with head-and-neck mass lesions, comparison of tractography results and operative findings with regards to mass and nerve relationship was also performed by two observers. RESULTS: Using the two regions-of-interest method, the greatest fiber density of presumed inferior alveolar nerves was depicted at a maximum angle of 40 degrees and a minimum fiber length of 10 mm. DTT was successfully depicted in all 5 patients. In 4 patients, the relationship between DTT and operative findings was coincided or similar. The interobserver agreement was good. CONCLUSIONS: DTT of the neural fibers in the head and neck region is feasible using a clinical 3T magnetic resonance scanner. Data from a small number of patients with head-and-neck lesions show good agreement between tractography and operative results.