Two medicolegal autopsy cases of multinodular and vacuolating neuronal tumor revealed by postmortem MRI.

The multinodular and vacuolating neuronal tumor (MVNT) is a recently recognized brain lesion. MVNT has a characteristic appearance in MRI images and is potentially epileptogenic. To the best of our knowledge, no report has yet described this pathological entity in the forensic medicine literature. We present two medicolegal autopsy cases where postmortem MRI (PMMR) was useful to detect this lesion. Case 1: a man in his 30s, with about a 7-year history of intractable epilepsy and known MVNT died suddenly. Although MVNT was not detected in the initial morphological evaluation during autopsy, PMMR of the formalin-fixed brain revealed the lesion in the left frontal lobe. Histopathology confirmed it as a MVNT. Case 2: a man in his 20s hanged himself to death. PMMR prior to autopsy revealed MVNT in his brain, and the diagnosis was confirmed by a detailed histopathological evaluation. In both cases, postmortem CT was not useful for evaluation. The cases suggested that MVNT can cause sudden, unexpected epileptic death, and pre- or post-autopsy PMMR may be useful to detect it.

Pulse Sequences and Reconstruction in Fast MR Imaging of the Liver.

The liver moves with respiratory motion. Respiratory motion causes image artifacts as MRI is a motion-sensitive imaging modality; thus, MRI scan speed improvement has been an important technical development target for liver MRI for years. Recent pulse sequence and image reconstruction technology advancement has realized a fast liver MRI acquisition method. Such new technologies allow us to obtain liver MRI in a shorter time, particularly, within breath-holding time. Other benefits of new the technology and the higher spatial resolution liver MRI within a given scan time are improved slice coverage and smaller pixel size. In this review, MRI pulse sequence and reconstruction technologies to accelerate scan speed for T1- and T2-weighted liver MRI will be discussed. Technologies that reduce scan time while keeping image contrast, SNR and image spatial resolution are needed for fast MRI acquisition. We will discuss the progress of MRI acquisition methods, the enabling technology, established applications, current trends, and the future outlook.

Impact of deep learning reconstruction on intracranial 1.5 T magnetic resonance angiography.

PURPOSE: The purpose of this study was to evaluate whether deep learning reconstruction (DLR) improves the image quality of intracranial magnetic resonance angiography (MRA) at 1.5 T. MATERIALS AND METHODS: In this retrospective study, MRA images of 40 patients (21 males and 19 females; mean age, 65.8 ± 13.2 years) were reconstructed with and without the DLR technique (DLR image and non-DLR image, respectively). Quantitative image analysis was performed by placing regions of interest on the basilar artery and cerebrospinal fluid in the prepontine cistern. We calculated the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for analyses of the basilar artery. Two experienced radiologists evaluated the depiction of structures (the right internal carotid artery, right ophthalmic artery, basilar artery, and right superior cerebellar artery), artifacts, subjective noise and overall image quality in a qualitative image analysis. Scores were compared in the quantitative and qualitative image analyses between the DLR and non-DLR images using Wilcoxon signed-rank tests. RESULTS: The SNR and CNR for the basilar artery were significantly higher for the DLR images than for the non-DLR images (p < 0.001). Qualitative image analysis scores (p < 0.003 and p < 0.005 for readers 1 and 2, respectively), excluding those for artifacts (p = 0.072-0.565), were also significantly higher for the DLR images than for the non-DLR images. CONCLUSION: DLR enables the production of higher quality 1.5 T intracranial MRA images with improved visualization of arteries.

MR Imaging in the 21st Century: Technical Innovation over the First Two Decades.

Clinical MRI systems have continually improved over the years since their introduction in the 1980s. In MRI technical development, the developments in each MRI system component, including data acquisition, image reconstruction, and hardware systems, have impacted the others. Progress in each component has induced new technology development opportunities in other components. New technologies outside of the MRI field, for example, computer science, data processing, and semiconductors, have been immediately incorporated into MRI development, which resulted in innovative applications. With high performance computing and MR technology innovations, MRI can now provide large volumes of functional and anatomical image datasets, which are important tools in various research fields. MRI systems are now combined with other modalities, such as positron emission tomography (PET) or therapeutic devices. These hybrid systems provide additional capabilities.In this review, MRI advances in the last two decades will be considered. We will discuss the progress of MRI systems, the enabling technology, established applications, current trends, and the future outlook.

Reproducibility and Variability of Quantitative Cerebral Blood Flow Measured by Multi-delay 3D Arterial Spin Labeling According to Sex and Menstrual Cycle.

Purpose : To determine the reproducibility of corrected quantitative cerebral blood flow (qCBF) through measurement of transit flow time using multi-delay three-dimensional pseudo-continuous arterial spin labeling (pCASL) in healthy men and women and to evaluate the differences in qCBF between not only men and women, but also the follicular and luteal phases of the women's menstrual cycle. Methods : The participants were 16 healthy volunteers (8 men and 8 women ; mean age, 25.3 years). Two MRI were conducted for all participants ; female participants were conducted in the follicular and luteal phases. The reproducibility of qCBF values was evaluated by the intraclass correlation coefficient (ICC) and differences between the two groups were estimated by voxel-based morphometry (VBM) analysis. Results : The qCBF values were lower in men than in women, and those in females were significantly different between the follicular and luteal phases (P < 0.05). In VBM analysis, the qCBF values of the lower frontal lobes were significantly higher in women than in men (P < 0.05). The qCBF values of the frontal pole were significantly higher in the follicular phase than in the luteal phase (P < 0.01). Conclusion : Multi-delay pCASL can reveal physiological and sex differences in cerebral perfusion. J. Med. Invest. 67 : 321-327, August, 2020.

Optimal Plane Selection for Measuring Post-prandial Blood Flow Increase within the Superior Mesenteric Artery: Analysis Using 4D Flow and Computational Fluid Dynamics.

PURPOSE: 2D cine phase contrast (PC)-MRI is a standard velocimetry for the superior mesenteric artery (SMA); however, the optimal localization of the measurement plane has never been fully discussed previously. The purpose of this Institutional Review Board approved prospective and single arm study is to test whether flow velocimetry of the SMA with combined use of 2D cine PC-MRI and meal challenge is dependent on the localizations of the measurement planes and to seek optimal section for velocimetry. METHODS: Seven healthy volunteers underwent cardiac phase resolved ECG gated 2D cine PC-MRI pre- and 30 min post-meal challenge at three measurement planes: proximal, curved mid section and distal straight section of the SMA at 3T. 4D Flow using 3D cine PC-MRI with vastly undersampled isotropic projection imaging (PC VIPR) was also performed right after 2D cine PC-MRI to delineate the flow dynamics within the SMA using streamline analysis. Two radiologists measured flow velocities, and rated the appearances of the abnormal flow in the SMA on streamlines derived from the 4D Flow and the computational fluid dynamics (CFD). RESULTS: 2D cine PC-MRI measured increased temporally averaged flow velocity (mm/s) after the meal challenge only in the proximal (129.3 vs. 97.8, P = 0.0313) and distal section (166.9 vs. 96.2, P = 0.0313), not in the curved mid section (113.1 vs. 85.5, P = 0.0625). The average velocities were highest and their standard errors (8.5-26.5) were smallest at the distal straight section both before and after the meal challenge as compared with other sections. The streamline analysis depicted more frequent appearances of vertical or helical flow in the curved mid section both on 4D Flow and CFD (κ: 0.27-0.68). CONCLUSION: SMA velocimetry with 2D cine PC-MRI was dependent on the localization of the measurement planes. Distal straight section, not in the curved mid section is recommended for MR velocimetry.

Comparison of Silent Navigator Waveform Generation Methods.

The silent navigator technique utilizes a non-selective excitation and an appropriate respiratory waveform generation method is necessary for an accurate motion detection. We compared three methods for silent navigator waveform generation. The profile generation method with coil selection (prof-selection) resulted in a high cross correlation with bellows signals and a large respiration amplitude. The prof-selection method should be used for silent navigator waveform generation.

Three-dimensional arterial spin labeling imaging with a DANTE preparation pulse.

On arterial spin-labeled (ASL) images, areas of bright intravascular signal will appear when the post labeling delay time is shorter than arterial transit time. Vascular suppression (VS) schemes reduce artefactual bright signal by dephasing intravascular labeled spins. However, existing VS methods, such as Motion-Sensitized Driven-Equilibrium (MSDE), decrease the uniformity of the signal intensity distribution and extend the echo time. The purpose of this study is to compare VS using a Delays Alternating with Nutation for Tailored Excitation (DANTE) preparation pulse, with MSDE for ASL imaging on a flow phantom and volunteer data. In the phantom study, the signal decay pattern of moving water was similar for both methods. In the volunteer study, the bright intravascular signal artifact was decreased by both methods. However right-left differences in signal intensity were smaller using DANTE-prepared ASL. The proposed DANTE-prepared ASL sequence has a vessel suppression effect while maintaining a uniform signal intensity distribution. This study indicates that DANTE is a potentially useful method for vessel suppression in ASL imaging.

Silent navigator-triggered silent MRI of the abdomen.

PURPOSE: To develop and demonstrate the feasibility of a silent respiratory navigator technique for prospective triggering, which was incorporated into a three-dimensional radial zero-echo-time sequence for respiratory navigated silent abdominal imaging. METHODS: A nonselective hard excitation radiofrequency pulse was used for the navigator sequence with a derated readout gradient, to avoid generation of high levels of acoustic noise. The acquired navigator signals were processed in real time and used for prospective triggering of the zero-echo-time sequence. Ten healthy volunteers were scanned using the proposed and conventional techniques at 1.5 T. An acoustic noise measurement with A-weighted continuous equivalent sound pressure level was also performed. RESULTS: The sound pressure-level values of the background noise, zero-echo-time imaging, conventional, and silent navigators were 68.3, 68.4, 102.5, and 69.4 dBA, respectively. Excellent correlation with correlation coefficients greater than 0.9 was observed between the bellows signals and displacement values calculated from the navigators. Sharpness of the portal vein of both conventional and silent navigator-triggered images was significantly higher than those of nontriggered images. CONCLUSIONS: The silent navigator-triggered zero-echo-time technique is feasible and might improve image quality and workflow of abdominal MRI of patients who are prone to acoustic noise. Magn Reson Med 79:2170-2175, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Four-dimensional phase-contrast vastly undersampled isotropic projection reconstruction (4D PC-VIPR) MR evaluation of the renal arteries in transplant recipients: Preliminary results.

PURPOSE: To assess the performance of four-dimensional phase-contrast vastly undersampled isotropic projection reconstruction (4D PC-VIPR) at 3.0T in depicting intrarenal arteries compared with computed tomography angiography (CTA), and its correlation with arterial flowmetry in comparison with Doppler ultrasonography (DUS). MATERIALS AND METHODS: In our prospective single-arm study, subjects were 25 patients who underwent renal transplant-related surgery at our hospital between July 2011 and June 2015. In the morphological study, depictions of renal artery branches delineated by magnetic resonance angiography (MRA)/4D PC-VIPR without gadolinium contrast agent were compared in seven living transplant recipients with the same kidney delineated by CTA in seven living transplant donors. In the flowmetric study, flow velocities in the renal (main stem), segmental, and interlobar arteries during systole and diastole were measured in 12 recipients using noncontrast MRA/4D PC-VIPR, and were compared with those obtained from DUS. RESULTS: Concerning MRA, average confidence levels of delineation rated by six observers for secondary to third level renal artery branches were 82.9-100% and for the fourth to fifth branches were 60.8-89.7% (average kappa value of 0.588 [95% confidence interval: 0.522-0.653]). Total flow velocities measured using 4D PC-VIPR and DUS demonstrated significant correlations during both systole and diastole with acceptable bias (r = 0.902; P < 0.001 in systole and r = 0.734; P < 0.001 in diastole). CONCLUSION: 4D PC-VIPR was useful in generating both morphological and hemodynamic information for evaluation of transplant intrarenal arteries without the need for contrast media. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:595-603.

Intracranial Plaque Characterization in Patients with Acute Ischemic Stroke Using Pre- and Post-Contrast Three-Dimensional Magnetic Resonance Vessel Wall Imaging.

BACKGROUND: Magnetic resonance vessel wall imaging (VWI) techniques have been developed to assess atherosclerotic plaques in intracranial arteries, which are a cardinal cause of ischemic stroke. However, the clinical roles of plaque-related vulnerability and inflammation remain unclear. Hence, we evaluated plaque characteristics using VWI of the proximal middle cerebral artery (M1) in patients with acute ischemic stroke. METHODS: We prospectively examined 30 consecutive patients with acute noncardioembolic stroke in the M1 territory using pre-/postcontrast T1-weighted (T1W) three-dimensional (3D) VWI with a 3-Tesla scanner. The contrast ratio (CR) and contrast enhancement of the plaques were measured bilaterally at M1. RESULTS: Plaques were identified in the bilateral M1s of all patients, and no substantial stenosis existed. The M1 plaque CRs ipsilateral to the infarct (46.7%-67.9%) were significantly higher than the plaque CRs on the contralateral side (34.3%-69.4%), particularly in patients with lacunar infarcts (P <.01). In contrast, the occurrence of plaque enhancement was not different between the ipsilateral (20.0%) and contralateral (16.7%) sides. Further, the CRs in the nonlacunar group were significantly higher than the CRs in the lacunar group (P <.05), whereas enhanced plaques tended to be more frequent in the nonlacunar group, but this difference was not significant (P = .09). CONCLUSIONS: T1W 3D-VWI revealed that the signal intensity of M1 plaques was significantly higher in the affected side and in nonlacunar-type infarcts of patients with acute stroke, suggesting that unstable plaques in the M1 can cause stroke events presumably due to atherothrombotic mechanisms.

Motion detection improvement of a pencil-beam navigator echo using a gradient reversal technique.

PURPOSE: To develop and demonstrate the feasibility of a pencil-beam navigator using a gradient reversal technique for reducing signal contamination from undesired excitation for precise motion detection and correction. MATERIALS AND METHODS: The navigator echo was obtained using normal and reversed gradient waveforms sequentially in three-dimensional spoiled gradient-recalled echo imaging. These two signals were combined in the complex domain for generating the final navigator data, which were used for detecting the diaphragm motion to nullify the side lobe effects with the smallest radius from the beam center. The navigator signals were compared with and without the proposed technique in phantom and human scans. In addition, navigator-gated imaging was performed in the human scans. RESULTS: In a phantom experiment, the proposed technique diminished signals from a phantom placed outside the beam's area. In human scans, the proposed technique reduced undesired signals in the navigator data for all subjects. The resultant images had fewer motion-induced ghosts than the images from the conventional technique for 8 subjects out of 10. CONCLUSIONS: We have demonstrated that the gradient reversal technique reduced undesired signals in a pencil-beam navigator. This technique can be an alternative for free-breathing abdominal scan when the conventional navigator technique cannot detect the patient's respiratory motion precisely.

Robust automated bolus tracker positioning for MRI liver scans.

PURPOSE: To improve the workflow of MRI abdominal scans by reducing the examination time and operator skill dependence related to bolus tracker positioning. METHODS: Ten or more axial images of two-dimensional scout scan were analyzed to identify the aorta and detect its center position using the mean shift to allow automated bolus tracker placement. Adaptive boosting (AdaBoost) classifier was used to identify the aorta rotating a sub-window around the cerebrospinal fluid (CSF), the location of which was detected in each axial image in advance. The search region of the aorta in the next inferior axial image was restricted to half to reduce computation time. Tests were conducted using the proposed method with a 1.5T scanner in 31 volunteers. RESULTS: The success rate of aorta detection was 98.4%, and the accuracy of center location was around 0 - 5mm shift from the true center. The computation time was 30s on MATLAB, which was half that required for non-restrictive search. CONCLUSION: The proposed algorithm was able to accurately detect the aorta in all volunteers with practical computation time so that the automated bolus tracker placement improved the workflow of MRI abdominal scans.

Detection of vessel wall lesions in spontaneous symptomatic vertebrobasilar artery dissection using T1-weighted 3-dimensional imaging.

BACKGROUND: Spontaneous intracranial vertebrobasilar artery dissection (iVBD) is a cause of ischemic stroke and subarachnoid hemorrhage in young adults that can be detected noninvasively by using multisequence magnetic resonance imaging (MRI). However, MRI findings are sometimes difficult to interpret, and its accuracy tends to be suboptimal, especially during the acute period. Therefore, we investigated whether 3-dimensional (3D) vessel wall imaging (VWI) technique could readily detect iVBD lesions in acute phase patients. METHODS: Sixteen consecutive patients with acute ischemic stroke caused by iVBD were prospectively examined with a 1.5-T magnetic resonance scanner. T1-weighted (T1W) 3D-VWI was obtained using a flow-sensitized 3D fast spin-echo technique. In addition, multisequence MRI comprising magnetic resonance angiography (MRA), basiparallel anatomical scanning (BPAS), and axial T1W imaging (T1WI) were also examined. Presence of luminal stenosis, aneurysmal dilatation, intramural high signal, and intimal flap/double lumen of the vertebral and basilar arteries were visually assessed using each technique. RESULTS: On 3D-VWI, luminal stenosis, aneurysmal dilatation, intramural high signal, and intimal flap were observed in 16 (100%), 11 (68.8%), 16 (100%), and 1 (6.3%) patients, respectively. In contrast, on conventional techniques, these findings were observed in 15 (93.8%, MRA with BPAS), 12 (75.0%, MRA with BPAS), 12 (75.0%, T1WI), and 12 (75.0%, MRA) patients, respectively. CONCLUSIONS: The T1W 3D-VWI can directly visualize vessel wall iVBD lesions during the acute period of stroke compared with multisequence MRI.

Evaluating middle cerebral artery atherosclerotic lesions in acute ischemic stroke using magnetic resonance T1-weighted 3-dimensional vessel wall imaging.

BACKGROUND: Atherosclerotic lesions in intracranial arteries are a leading cause of ischemic stroke. Magnetic resonance angiography (MRA) is often used to assess atherosclerotic changes by detecting luminal narrowing, whereas it cannot directly visualize atherosclerotic lesions. Here, we used a 3-dimensional vessel wall imaging (3D-VWI) technique to evaluate intracranial arterial wall changes in acute stroke. METHODS: Eighteen consecutive patients with acute noncardioembolic stroke in the middle cerebral artery (MCA) territory who were prospectively examined with a 1.5-T magnetic resonance scanner were studied. T1-weighted (T1-W) 3D-VWI was obtained using a flow-sensitized 3D fast-spin echo technique. Wall thickening of MCA that suggests atherosclerotic plaques was visually evaluated and the contrast ratio (CR) of signal intensity of the lesions to that of the corpus callosum was calculated and compared with stenotic changes by MRA. RESULTS: Wall thickenings of the MCA ipsilateral and contralateral to the lesion were observed in almost all patients on 3D-VWI (94.4% and 94.4%, respectively), whereas MRA showed stenotic changes of 50% only in 1 patient (5.9%; P < .001). The CR of the thickened wall in the ipsilateral MCA was significantly higher than that in the contralateral MCA (median, .53 and .45, respectively; P = .028), suggesting of unstable plaques consisting of hemorrhage or lipid. CONCLUSIONS: The T1-W 3D-VWI can provide direct visualization of atherosclerotic lesions of the intracranial arteries in stroke patients, and it can detect signal change suggestive of unstable plaque.

Enhancement of respiratory navigator-gated three-dimensional spoiled gradient-recalled echo sequence with variable flip angle scheme.

PURPOSE: To develop and demonstrate the feasibility of a new technique for respiratory-gated, fat-suppressed, three-dimensional spoiled gradient-recalled echo (3D-SPGR) with navigator gating for more accurate and robust motion detection. METHODS: A navigator-gated 3D-SPGR technique was modified to include a wait period immediately prior to the navigator sequence for magnetization recovery. Furthermore, a variable flip angle scheme was realized by a combination of ramp-up, ramp-down, and attenuation strategies for optimizing point spread functions. Phantom and human experiments were conducted with our technique on 1.5T scanners. RESULTS: Using the method, T1-weighted 3D images with improved signal homogeneity were acquired with a maximum flip angle of 30° in phantom and human tests. Also, compared with the conventional navigator-gated 3D-SPGR, accurate respiratory motion detection of free-breathing subjects was provided, leading to reduced motion artifacts. CONCLUSION: The combination of wait insertion and the variable flip angle method improved both motion detection accuracy and image homogeneity in a navigator-gated 3D-SPGR study.

Plasma levels of 3-methoxy-4-hydroxyphenylglycol are associated with microstructural changes within the cerebellum in the early stage of first-episode schizophrenia: a longitudinal VBM study.

The aims of this study are to determine how the interval changes of the brain structures in the early stage of first-episode schizophrenia relate to the interval changes in the clinical data, including the clinical symptoms of schizophrenia and catecholaminergic measures (plasma homovanillic acid [HVA] and 3-methoxy-4-hydroxyphenylglycol [MHPG]). Regional brain volumes and fractional anisotropy (FA)/mean diffusivity (MD) with diffusion tensor imaging (DTI) were measured at baseline and 6-month follow-up in a 3T magnetic resonance imaging (MRI) system in a cohort of 16 schizophrenic patients, who were in their first episode at the time of baseline MRI. At the time of baseline and follow-up MRI, all 16 patients underwent evaluations that included a psychopathological assessment (Positive and Negative Syndrome Scale [PANSS]) and peripheral catecholaminergic measures (plasma MHPG or HVA). For interval changes between baseline and follow-up MRI data (morphological change, MD, and FA), the correlation/regression analysis was performed as a series of single regression correlations in Statistical Parametric Mapping 5, with the interval changes in PANSS or plasma HVA and MHPG as the covariates of interest. Positive and inverse correlations contrasts were created, and in this preliminary analysis, a family-wise error-corrected threshold of P<0.05 was considered significant. In the correlation/regression analysis, a positive correlation between the FA in the right cerebellar vermis and the MHPG was observed. No significant correlations between the brain volume or MD and any laboratory data (plasma HVA and MHPG) were found. During the 6-month follow-up in the early stage of first-episode schizophrenia, the MHPG changes were correlated with the microstructural FA changes in the cerebellum, which may reflect the functional connections of the noradrenergic system in the cerebellum.

Improved volumetric measurement of brain structure with a distortion correction procedure using an ADNI phantom.

PURPOSE: Serial magnetic resonance imaging (MRI) images acquired from multisite and multivendor MRI scanners are widely used in measuring longitudinal structural changes in the brain. Precise and accurate measurements are important in understanding the natural progression of neurodegenerative disorders such as Alzheimer's disease. However, geometric distortions in MRI images decrease the accuracy and precision of volumetric or morphometric measurements. To solve this problem, the authors suggest a commercially available phantom-based distortion correction method that accommodates the variation in geometric distortion within MRI images obtained with multivendor MRI scanners. METHODS: The authors' method is based on image warping using a polynomial function. The method detects fiducial points within a phantom image using phantom analysis software developed by the Mayo Clinic and calculates warping functions for distortion correction. To quantify the effectiveness of the authors' method, the authors corrected phantom images obtained from multivendor MRI scanners and calculated the root-mean-square (RMS) of fiducial errors and the circularity ratio as evaluation values. The authors also compared the performance of the authors' method with that of a distortion correction method based on a spherical harmonics description of the generic gradient design parameters. Moreover, the authors evaluated whether this correction improves the test-retest reproducibility of voxel-based morphometry in human studies. RESULTS: A Wilcoxon signed-rank test with uncorrected and corrected images was performed. The root-mean-square errors and circularity ratios for all slices significantly improved (p < 0.0001) after the authors' distortion correction. Additionally, the authors' method was significantly better than a distortion correction method based on a description of spherical harmonics in improving the distortion of root-mean-square errors (p < 0.001 and 0.0337, respectively). Moreover, the authors' method reduced the RMS error arising from gradient nonlinearity more than gradwarp methods. In human studies, the coefficient of variation of voxel-based morphometry analysis of the whole brain improved significantly from 3.46% to 2.70% after distortion correction of the whole gray matter using the authors' method (Wilcoxon signed-rank test, p < 0.05). CONCLUSIONS: The authors proposed a phantom-based distortion correction method to improve reproducibility in longitudinal structural brain analysis using multivendor MRI. The authors evaluated the authors' method for phantom images in terms of two geometrical values and for human images in terms of test-retest reproducibility. The results showed that distortion was corrected significantly using the authors' method. In human studies, the reproducibility of voxel-based morphometry analysis for the whole gray matter significantly improved after distortion correction using the authors' method.

Automated scan prescription for MR imaging of deformed and normal livers.

PURPOSE: We propose an automated scan prescription to assess normal and deformed livers and demonstrate its efficacy in normal volunteers and in simulated deformed livers. METHODS: Our automated scan prescription can be used to identify the upper and lower edges of the liver enables in commonly used axial slice positioning. The liver's upper edge is detected by template matching and finally identified by applying an active shape model to a sagittal projection image. The lower edge is detected using a maximum a posteriori (MAP) probability estimate that utilizes statistical information from a region of interest (ROI) placed in the liver. This places no restraints on liver shape and is therefore effective in assessing a deformed liver. Following institutional review and approval, we tested our method in 45 healthy volunteers. We also used clinical information to simulate deformed livers and tested our method with those datasets offline. RESULTS: We could detect the upper edges within an error range of -3 to 6 mm, even without intensity correction for normal volunteers. Similar detection of the lower edges with maximum 21-mm and 7.84-mm standard deviation for normal volunteers confirmed the superior efficacy of our modified approach for deformed livers to that using our previous method. Clinical use required approximately 10 s' computational time on a Core i5 laptop with 2-GB memory. CONCLUSION: We propose a method for automated scan prescription in magnetic resonance (MR) imaging of the liver and demonstrate the efficacy of our algorithm for evaluating deformed livers within a practical computation time. Detection of liver edges of various shapes by applying the MAP estimate combined with statistical information from the ROI demonstrated the potential clinical utility of this technique.