Evaluation of 4D Flow MRI-Derived Relative Residence Time as a Marker for Cirrhosis Associated Portal Vein Thrombosis.

BACKGROUND: Portal vein thrombosis (PVT) is thought to arise from stagnant blood flow, yet conclusive evidence is lacking. Relative residence time (RRT) assessed using 4D Flow MRI may offer insight into portal flow stagnation. PURPOSE: To explore the relationship between RRT values and the presence of PVT in cirrhotic participants. STUDY TYPE: Prospective. POPULATION: Forty-eight participants with liver cirrhosis (27 males, median age 67 years [IQR: 57-73]) and 20 healthy control participants (12 males, median age 45 years [IQR: 40-54]). FIELD STRENGTH/SEQUENCE: 3 T/4D Flow MRI. ASSESSMENT: Laboratory (liver and kidney function test results and platelet count) and clinical data (presence of tumors and other imaging findings), and portal hemodynamics derived from 4D Flow MRI (spatiotemporally averaged RRT [RRT-mean], flow velocity, and flow rate) were analyzed. STATISTICAL TESTS: We used multivariable logistic regression, adjusted by selected covariates through the Lasso method, to explore whether RRT-mean is an independent risk factor for PVT. The area under the ROC curve (AUC) was also calculated to assess the model's discriminative ability. P < 0.05 indicated statistical significance. RESULTS: The liver cirrhosis group consisted of 16 participants with PVT and 32 without PVT. Higher RRT-mean values (odds ratio [OR] 11.4 [95% CI: 2.19, 118]) and lower platelet count (OR 0.98 per 1000 µL [95% CI: 0.96, 0.99]) were independent risk factors for PVT. The incorporation of RRT-mean (AUC, 0.77) alongside platelet count (AUC, 0.75) resulted in an AUC of 0.84. When including healthy control participants, RRT-mean had an adjusted OR of 12.4 and the AUC of the combined model (RRT-mean and platelet count) was 0.90. DATA CONCLUSION: Prolonged RRT values and low platelet count were significantly associated with the presence of PVT in cirrhotic participants. RRT values derived from 4D Flow MRI may have potential clinical relevance in the management of PVT. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.

Four-dimensional Flow MRI Assessment of Portal Hemodynamics and Hepatic Regeneration after Portal Vein Embolization.

Background Percutaneous transhepatic portal vein (PV) embolization (PVE) is a standard preoperative procedure for advanced biliary cancer when the future liver remnant (FLR) is insufficient, yet the effect of this procedure on portal hemodynamics is still unclear. Purpose To assess whether four-dimensional (4D) MRI flowmetry can be used to estimate FLR volume and to identify the optimal time for this measurement. Materials and Methods This prospective single-center study enrolled consecutive adult patients with biliary cancer who underwent percutaneous transhepatic PVE for the right liver between June 2020 and November 2022. Portal hemodynamics were assessed using 4D flow MRI before PVE and within 1 day (0-day group) or 3-4 days (3-day group) after PVE. FLR volume was measured using CT before PVE and after PVE but before surgery. Blood flow changes were analyzed with the Wilcoxon signed rank test, and correlations with Spearman rank correlation. Results The 0-day group included 24 participants (median age, 72 years [IQR, 69-77 years]; 17 male participants), and the 3-day group included 13 participants (median age, 71 years [IQR, 68-78 years]; eight male participants). Both groups showed increased left PV (LPV) flow rate after PVE (0-day group: from median 3.72 mL/sec [IQR, 2.83-4.55 mL/sec] to 9.48 mL/sec [IQR, 8.12-10.7 mL/sec], P < .001; 3-day group: from median 3.65 mL/sec [IQR, 2.14-3.79 mL/sec] to 8.16 mL/sec [IQR, 6.82-8.98 mL/sec], P < .001). LPV flow change correlated with FLR volume change relative to the number of days from PVE to presurgery CT only in the 3-day group (ρ = 0.62, P = .02; 0-day group, P = .11). The output of the regression equation for estimating presurgery FLR volume correlated with CT-measured volume (ρ = 0.78; P = .002). Conclusion Four-dimensional flow MRI demonstrated increased blood flow in residual portal branches 3-4 days after PVE, offering insights for estimating presurgery FLR volume. Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Roldán-Alzate and Oechtering in this issue.

Pre-Operative Four Dimensional Flow Sensitive Magnetic Resonance Imaging Assessment of Aortic Side Branches as a Method to Predict Risk of Type II Endoleak Resulting in Sac Enlargement After EVAR.

OBJECTIVE: To predict sac enlargement with type II endoleak (ELII) before endovascular aneurysm repair (EVAR) using four dimensional flow sensitive magnetic resonance imaging (4D flow MRI). METHODS: A single centre retrospective analysis of prospectively collected data was conducted. Patients with an abdominal aortic aneurysm (AAA) who underwent EVAR between 2013 and 2019 were included. Aortic branches occluded pre-EVAR, and patients with endoleaks other than ELII were excluded. The aortic branch diameter, peak flow velocity (PFVe), and amplitude of the dynamics of flow volume (AFV) were measured in each aortic branch pre-EVAR. Total flow volume per minute (TFV/min), defined as the sum of AFV/min, was calculated in each case. According to computed tomography findings one year post-EVAR, the aortic branches and patients were divided into patent vessel and occluded vessel groups and sac expanding and non-expanding groups. PFVe, AFV/min, and TFV/min were analysed via receiver operating characteristic curve analysis. RESULTS: The patent aortic branches pre-EVAR (69 inferior mesenteric arteries [IMAs]; 249 lumbar arteries [LAs]) of 100 patients were included. Patent IMAs (n = 14) and occluded IMAs (n = 55), patent LAs (n = 23) and occluded LAs (n = 226), and expanding (n = 9) and non-expanding (n = 91) groups were compared, respectively. No statistically significant difference was observed in branch diameters (IMA; patent, 2.5 ± 0.8 mm, occluded, 2.5 ± 0.8 mm, p < .78 and LA; patent, 1.5 ± 0.3 mm, occluded, 1.5 ± 0.4 mm, p < .35). PFVe (IMA; patent, 262.6 mm2/sec, occluded, 183.4 mm2/sec and LA; patent, 142.6 mm2/sec, occluded, 47.7 mm2/sec) and AFV/min (IMA; patent, 8.4 mL, occluded, 5.2 mL and LA; patent, 4.2 mL, occluded, 1.4 mL) were higher in the patent vessel group (p < .050). TFV/min was statistically significantly higher in the expanding group (24.1 mL/min) than in the non-expanding group (7.0 mL/min) (p < .010). CONCLUSION: Pre-EVAR haemodynamic analyses using 4D flow MRI were useful to detect aortic branches responsible for ELII and to predict AAA cases with sac enlargement. This analysis suggests a new strategy for pre-EVAR aortic branch embolisation.

"Speckled Enhancement" on Gd-EOB-DTPA Enhanced MR Imaging of Primary Hepatic Mucosa-associated Lymphoid Tissue Lymphoma.

PURPOSE: To elucidate MRI features of primary hepatic mucosa-associated lymphoid tissue (MALT) lymphoma, particularly, the "speckled enhancement" on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI. METHODS: The institutional review board approved this retrospective observational study and waived informed consent. Using our picture archiving and communication systems and electronic medical records, five patients histopathologically diagnosed as hepatic MALT lymphoma and clinically confirmed as primary lesions who had undergone dynamic contrast-enhanced (DCE)-CT and DCE-MRI with Gd-EOB-DTPA were identified from September 2009 to December 2020. Two radiologists assessed their CT and MRI data in consensus with a pathologist's advice. RESULTS: Overall, five lesions in five patients were included in this study. Precontrast CT showed hypoattenuation in all lesions. In the arterial phase of DCE-CT, four lesions (80%) showed hyperattenuation, whereas all lesions showed iso- to hypoattenuation in the delayed phase. A vessel penetration sign was also observed in all lesions. On MRI, all lesions showed hypointensity on T1-weighted images, hyperintensity on T2-weighted images, and restricted diffusion on diffusion-weighted images. Both DCE-CT and DCE-MRI with Gd-EOB-DTPA showed similar enhancement patterns, except for the hepatocyte phase. Notably, however, four out of five lesions showed characteristic "speckled enhancement" that refers to punctate positive enhancements within the low signal lesions on the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI pathologically confirmed to be hepatocyte clusters that remained in the tumor. CONCLUSION: Primary hepatic MALT lymphomas were characterized by arterial phase enhancement, restricted diffusion, vessel penetration sign, and more specifically "speckled enhancement" in the hepatobiliary phase of DCE-MRI with Gd-EOB-DTPA.

Assessing the Complicated Venous Hemodynamics and Therapeutic Outcomes of Budd-Chiari Syndrome with Respiratory-gated 4D Flow MR Imaging During the Expiratory and Inspiratory Phases.

A man in his 50s with Budd-Chiari syndrome diagnosed with the suprahepatic inferior vena cava (IVC) obstruction on CT was assessed using 4D Flow MRI before and after balloon angioplasty. 4D Flow MRI acquired in two respiratory phases, depicted complex hemodynamic and respiratory variability, and a jet stream at the narrowed channel of the membranous IVC. Post-interventional 4D Flow MRI showed that the IVC blood flow increased with corrected flow directions in the infrarenal IVC.

Postendovascular Aneurysmal Repair Increase in Local Energy Loss for Fusiform Abdominal Aortic Aneurysm: Assessments With 4D flow MRI.

BACKGROUND: Although endovascular aneurysmal repair (EVAR) is a preferred treatment for abdominal aortic aneurysm (AAA) owing to its low invasiveness, its impact on the local hemodynamics has not been fully assessed. PURPOSE: To elucidate how EVAR affects the local hemodynamics in terms of energy loss (EL). STUDY TYPE: Prospective single-arm study. FIELD STRENGTH/SEQUENCE: A 3.0 T/4D flow MRI using a phase-contrast three-dimensional cine-gradient-echo sequence. POPULATION: A total of 13 consecutive patients (median [interquartile range] age: 77.0 [73.0, 78.8] years, 11 male) scheduled for EVAR as an initial treatment for fusiform AAA. ASSESSMENT: 4D flow MRI covering the abdominal aorta and bilateral common iliac arteries and the corresponding stent-graft (SG) lumen was performed before and after EVAR. Plasma brain natriuretic peptide (BNP) was measured within 1 week before and 1 month after EVAR. The hemodynamic data, including mean velocity and the local EL, were compared pre-/post-EVAR. EL was correlated with AAA neck angle and with BNP. Patients were subdivided into deformed (N = 5) and undeformed SG subgroups (N = 8) and pre-/post-EVAR BNP compared in each. STATISTICS: Parametric or nonparametric methods. Spearman's rank correlation coefficients (r). The interobserver/intraobserver variabilities with Bland-Altman plots. A P value < 0.05 is considered significant. RESULTS: The mean velocity (cm/sec) at the AAA was five times greater after EVAR: 4.79 ± 0.32 vs. 0.91 ± 0.02. The total EL (mW) increased by 1.7 times after EVAR: 0.487 (0.420, 0.706) vs. 0.292 (0.192, 0.420). The total EL was proportional to the AAA neck angle pre-EVAR (r = 0.691) and post-EVAR (r = 0.718). BNP (pg/mL) was proportional to the total EL post-EVAR (r = 0.773). In the deformed SG group, EL (0.349 [0.261, 0.416]) increased 2.4-fold to 0.848 (0.597, 1.13), and the BNP 90.3 (53.6, 105) to 100 (67.2, 123) post-EVAR. CONCLUSION: The local EL showed a 1.7-fold increase after EVAR. The larger increase in the EL in the deformed SG group might be a potential concern for frail patients. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.

4D Flow MRI in the portal venous system: imaging and analysis methods, and clinical applications.

Thus far, ultrasound, CT, and 2D cine phase-contrast MRI has been adopted to evaluate blood flow and vascular morphology in the portal venous system; however, all these techniques have some shortcomings, such as limited field of view and difficulty in accurately evaluating blood flow. A new imaging technique, namely 3D cine phase-contrast (4D Flow) MRI, can acquire blood flow data of the entire abdomen at once and in a time-resolved manner, allowing visual, quantitative, and comprehensive assessment of blood flow in the portal venous system. In addition, a retrospective blood flow analysis, i.e., "retrospective flowmetry," is possible. Although the development of 4D Flow MRI for the portal system has been delayed compared to that for the arterial system owing to the lower flow velocity of the portal venous system and the presence of respiratory artifacts, several useful reports have recently been published as the technology has advanced. In the first part of this narrative review article, technical considerations of image acquisition and analysis methods of 4D Flow MRI for the portal venous system and the validations of their results are described. In the second part, the current clinical application of 4D Flow MRI for the portal venous system is reviewed.

Iodinated Contrast Media Substitution to Prevent Recurrent Hypersensitivity Reactions: A Systematic Review and Meta-Analysis.

Background Changing iodinated contrast media (ICM) may reduce the risk of recurrent ICM-induced hypersensitivity reactions in patients with a prior reaction. Purpose To perform a systematic review on the effectiveness of ICM change in comparison with no change to prevent recurrent ICM immediate hypersensitivity reactions. Materials and methods Multiple data bases were searched without language restriction between January 1990 and August 2021 to identify comparative studies of any design that included patients with a prior ICM hypersensitivity reaction to low-osmolality ICM and re-exposure to intravascular ICM. The methods used included a duplicate assessment of eligibility, double extraction of quantitative data, validity assessment, and random-effects meta-analysis. The primary outcome was the incidence of all-grade immediate recurrent hypersensitivity reactions. Secondary outcomes were the incidence of severe immediate recurrent hypersensitivity reactions and other adverse events associated with ICM change. Results Six retrospective observational studies at moderate to severe risk of bias assessed 7155 adult patients (4329 in the ICM change group and 2826 in the no-change group). Studies adopted nonstandardized switching methods, and the proportions of the ICM change group ranged between 19% (five of 27 examinations) and 80% (3104 of 3880 examinations). A Bayesian meta-analysis revealed that changing ICM was associated with a reduced risk of recurrent hypersensitivity reaction by 61% (risk ratio = 0.39; 95% credible interval [CrI]: 0.24, 0.58). The wide-ranging estimates of risk reduction were not explained by the risk of bias ratings, the event rates in the no-change group, the index-reaction severity, or the co-administered nonstandard premedication. Rare severe recurrent reactions (five studies with five events) precluded a conclusion (risk ratio = 0.34, favoring ICM change; CrI: 0.01, 3.74). Adverse events associated with ICM change were not reported. Conclusion In observational evidence of limited quality, iodinated contrast media (ICM)-change was associated with a reduced risk of recurrent immediate hypersensitivity reaction in patients with a prior ICM-induced hypersensitivity reaction. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by McDonald in this issue.

Clinical Application of 4D Flow MR Imaging for the Abdominal Aorta.

Blood vessels can be regarded as autonomous organs. The endothelial cells on the vessel surface serve as mechanosensors or mechanoreceptors for the flow velocity and turbulence of the blood flow in terms of wall shear stress (WSS), thereby monitoring changes in the flow velocity. Accordingly, the endothelial cells regulate the flow velocity by releasing numerous mediators. Such regulatory systems also trigger atherosclerosis, where the WSS decreases or fluctuates to maintain the flow velocity or local WSS. As occurrences of abdominal aortic aneurysms and aortic dissection are closely related to atherosclerosis, understanding the hemodynamics of the abdominal aorta is necessary to obtain useful information concerning the pathogenesis, diagnosis, and interventions. 4D flow MRI is beneficial for measuring the hemodynamics through comprehensive retrospective flowmetry of the entire spatio-temporal distributions of the flow vectors. This section focuses on abdominal aortic aneurysms and aortic dissection as representative examples of abdominal aortic diseases. Their hemodynamic characteristics and how hemodynamics is involved in their progression are described, and how 4D flow MRI can contribute to their assessment is also explained.

Why 4D Flow MRI? Real Advantages.

This special issue of Magnetic Resonance in Medical Sciences features the most recent reviews on 4D Flow MRI. These reviews deal with the current status of the emerging technique of 4D Flow MRI facilitated in various areas that are difficult to obtain with conventional flowmetry. MR signals inherently contain flow velocity information. In previous decades, in vivo blood flow measurement was traditionally performed by 2D methods, such as Doppler ultrasonography and 2D phase-contrast MRI, which have long been regarded as mature techniques in hemodynamic flowmetry. Although 2D velocimetries have many advantages over 4D Flow MRI in terms of cost and accessibility, and provide excellent temporal and in-plane spatial resolutions, they also have some disadvantages. The emerging technology of 4D Flow MRI can overcome the shortcomings of conventional 2D imaging. In recent years, hemodynamic analysis has witnessed significant progress that is primarily attributable to advances in 4D Flow MRI.

Technical Background for 4D Flow MR Imaging.

Recently, the hemodynamic assessments with 3D cine phase-contrast (PC) MRI (4D flow MRI) have attracted considerable attention from clinicians. Unlike 2D cine PC MRI, the technique allows for cardiac phase-resolved data acquisitions of flow velocity vectors within the entire FOV during a clinically viable period. Thus, the method has enabled retrospective flowmetry in the spatial and temporal axes, which are essential to derive hemodynamic parameters related to vascular homeostasis and those to the progression of the pathologies. Accelerations in imaging are critical for this technology to be clinically viable; however, a high SNR or velocity-to-noise ratio (VNR) is also vital for accurate flow measurements. In this chapter, the technologies enabling this difficult balance are discussed.

Does the Pulsatile Non-uniform Flow Matter in MR Flowmetry?

3D cine phase-contrast (4D flow) MRI is a sequence with great potential for non-invasive time-resolved 3D flowmetry at arbitrary vessel sections in various blood vessels. However, it is not widely known that the flowmetry with 4D flow MRI is vulnerable to pulsatile and non-uniform flow. Due to the limited spatial and temporal resolutions, averaging within the 3D voxel is occurring during the flowmetry. A simple solution is to avoid setting the measurement plane in the area where non-uniform flow is dominant, which is possible with an aid of streamline depictions generated by computational fluid dynamics (CFD) or 4D flow MRI data. Unlike 4D flow MRI, flowmetry in CFD simulation can use higher spatial and temporal resolution depending on computer performance; therefore, it is robust to fluctuating non-uniform flow. However, the performance of CFD simulations might be limited due to inlet conditions with low temporal resolution. Difficulty applying complex blood flow such as reflection flow from periphery may also limit accurate simulation. Caution should be taken when comparing the result of CFD simulation to that of 4D flow measurement.

Hemodynamic Parameters for Cardiovascular System in 4D Flow MRI: Mathematical Definition and Clinical Applications.

Blood flow imaging becomes an emerging trend in cardiology with the recent progress in computer technology. It not only visualizes colorful flow velocity streamlines but also quantifies the mechanical stress on cardiovascular structures; thus, it can provide the detailed inspections of the pathophysiology of diseases and predict the prognosis of cardiovascular functions. Clinical applications include the comprehensive assessment of hemodynamics and cardiac functions in echocardiography vector flow mapping (VFM), 4D flow MRI, and surgical planning as a simulation medicine in computational fluid dynamics (CFD).For evaluation of the hemodynamics, novel mathematically derived parameters obtained using measured velocity distributions are essential. Among them, the traditional and typical parameters are wall shear stress (WSS) and its related parameters. These parameters indicate the mechanical damages to endothelial cells, resulting in degenerative intimal change in vascular diseases. Apart from WSS, there are abundant parameters that describe the strength of the vortical and/or helical flow patterns. For instance, vorticity, enstrophy, and circulation indicate the rotating flow strength or power of 2D vortical flows. In addition, helicity, which is defined as the cross-linking number of the vortex filaments, indicates the 3D helical flow strength and adequately describes the turbulent flow in the aortic root in cases with complicated anatomies. For the description of turbulence caused by the diseased flow, there exist two types of parameters based on completely different concepts, namely: energy loss (EL) and turbulent kinetic energy (TKE). EL is the dissipated energy with blood viscosity and evaluates the cardiac workload related to the prognosis of heart failure. TKE describes the fluctuation in kinetic energy during turbulence, which describes the severity of the diseases that cause jet flow. These parameters are based on intuitive and clear physiological concepts, and are suitable for in vivo flow measurements using inner velocity profiles.

Consensus-Based Technical Recommendations for Clinical Translation of Renal Phase Contrast MRI.

BACKGROUND: Phase-contrast (PC) MRI is a feasible and valid noninvasive technique to measure renal artery blood flow, showing potential to support diagnosis and monitoring of renal diseases. However, the variability in measured renal blood flow values across studies is large, most likely due to differences in PC-MRI acquisition and processing. Standardized acquisition and processing protocols are therefore needed to minimize this variability and maximize the potential of renal PC-MRI as a clinically useful tool. PURPOSE: To build technical recommendations for the acquisition, processing, and analysis of renal 2D PC-MRI data in human subjects to promote standardization of renal blood flow measurements and facilitate the comparability of results across scanners and in multicenter clinical studies. STUDY TYPE: Systematic consensus process using a modified Delphi method. POPULATION: Not applicable. SEQUENCE FIELD/STRENGTH: Renal fast gradient echo-based 2D PC-MRI. ASSESSMENT: An international panel of 27 experts from Europe, the USA, Australia, and Japan with 6 (interquartile range 4-10) years of experience in 2D PC-MRI formulated consensus statements on renal 2D PC-MRI in two rounds of surveys. Starting from a recently published systematic review article, literature-based and data-driven statements regarding patient preparation, hardware, acquisition protocol, analysis steps, and data reporting were formulated. STATISTICAL TESTS: Consensus was defined as ≥75% unanimity in response, and a clear preference was defined as 60-74% agreement among the experts. RESULTS: Among 60 statements, 57 (95%) achieved consensus after the second-round survey, while the remaining three showed a clear preference. Consensus statements resulted in specific recommendations for subject preparation, 2D renal PC-MRI data acquisition, processing, and reporting. DATA CONCLUSION: These recommendations might promote a widespread adoption of renal PC-MRI, and may help foster the set-up of multicenter studies aimed at defining reference values and building larger and more definitive evidence, and will facilitate clinical translation of PC-MRI. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 1.

Four-dimensional flow magnetic resonance imaging visualizes reverse vortex pattern and energy loss increase in left bundle branch block.

AIMS: This study aimed to investigate the intraventricular blood flow pattern of patients with left bundle branch block (LBBB) using four-dimensional flow magnetic resonance imaging (4D-flow MRI). METHODS AND RESULTS: We performed 4D-flow MRI for 16 LBBB patients (LBBB group) and 16 propensity score-matched patients with a normal QRS duration (non-LBBB group). The energy loss (EL) in the left ventricle was evaluated. In both groups, blood flow from the mitral valve to the apex of the heart and left ventricular (LV) outflow tract during LV diastole were observed. Vortices were also observed in both groups. There were two patterns of vortices: unidirectional clockwise rotation and counterclockwise rotation taking place from the mid-diastole to the systole (reverse pattern). The reverse pattern was observed significantly more frequently in the LBBB group (LBBB 94% vs. non-LBBB 19%, P < 0.001). The interobserver agreement for the streamline analysis was good (kappa = 0.68). The maximum EL was significantly higher in the LBBB group [LBBB 12 (11-15) mW vs. non-LBBB 8.0 (6.2-9.7) mW, P < 0.001]. CONCLUSION: Left bundle branch block patients may suffer from inefficient LV haemodynamics reflected by non-physiological counterclockwise vortices and increased EL. Thus, the shape of the vortices and EL in the left ventricle can serve as markers of LV mechanical dyssynchrony in LBBB patients and could be investigated as predictors of response to cardiac resynchronization therapy.

A case of intraductal tubulopapillary neoplasm of the pancreas originating from the branch duct: cast in the mold sign.

A 59-year-old man with jaundice and lower common bile duct stenosis was referred to our institution for diagnosis and treatment. Computed tomography and magnetic resonance imaging showed a well-circumscribed smoothly marginated solid mass lesion in the pancreatic head. He underwent pyloric preserving pancreatoduodenectomy. Histopathological specimen revealed that the mass was located in the dilated branch duct of the pancreatic head, and an intraductal tubulopapillary neoplasm originating from the branch pancreatic duct was diagnosed. On magnetic resonance cholangiopancreatography, the mass within the dilated duct branch in the pancreatic head was similar to a "cast in the mold" image, which we retrospectively deemed, might be reflecting the nature of this tumor.

Imaging diagnosis of autoimmune pancreatitis: computed tomography and magnetic resonance imaging.

Autoimmune pancreatitis (AIP) is a pancreatic phenotype of IgG4-related systemic disease. Since its first description in the literature, characteristic imaging features have gradually become known to many clinicians encompassing various specialties in the past quarter century. CT and MRI have been the workhorses for imaging diagnosis of AIP. Typical features include sausage-like swelling of the focal or entire pancreas, duct-penetrating sign, a capsule-like rim of the affected lesions, and homogeneous delayed enhancement or enhanced duct sign after contrast administration, as well as characteristic combined findings reflecting coexisting pathologies in the other organs as a systemic disease. In this review, recent and future developments in CT and MRI that may help diagnose AIP are discussed, including restricted diffusion and perfusion and increased elasticity measured using MR.

How Memory Switches Brain Responses of Patients with Post-traumatic Stress Disorder.

To characterize the brain responses to traumatic memories in post-traumatic stress disorder (PTSD), we conducted task-employed functional magnetic resonance imaging and, in the process, devised a simple but innovative approach-correlation computation between task conditions. A script-driven imagery task was used to compare the responses with a script of the patients' own traumatic memories and with that of tooth brushing as a daily activity and to evaluate how eye movement desensitization and reprocessing (EMDR), an established therapy for PTSD, resolved the alterations in patients. Nine patients with PTSD (seven females, aged 27-50 years) and nine age- and gender-matched healthy controls participated in this study. Six patients underwent the second scan under the same paradigm after EMDR. We discovered intense negative correlations between daily and traumatic memory conditions in broad areas, including the hippocampus; patients who had an intense suppression of activation during daily recognition showed an intense activation while remembering a traumatic memory, whereas patients who had a hyperarousal in daily recognition showed an intense suppression while remembering a traumatic memory as a form of "shut-down." Moreover, the magnitude of the discrepancy was reduced in patients who remitted after EMDR, which might predict an improved prognosis of PTSD.

Daikenchuto increases blood flow in the superior mesenteric artery in humans: A comparison study between four-dimensional phase-contrast vastly undersampled isotropic projection reconstruction magnetic resonance imaging and Doppler ultrasound.

Respiratory-gated four-dimensional phase-contrast vastly undersampled isotropic projection reconstruction (4D PC-VIPR) is magnetic resonance (MR) imaging technique that enables analysis of vascular morphology and hemodynamics in a single examination using cardiac phase resolved 3D phase-contrast magnetic resonance imaging. The present study aimed to assess the usefulness of 4D PC-VIPR for the superior mesenteric artery (SMA) flowmetry before and after flow increase was induced by the herbal medicine Daikenchuto (TJ-100) by comparing it with Doppler ultrasound (DUS) as a current standard. Twenty healthy volunteers were enrolled in this prospective single-arm study. The peak cross-sectionally averaged velocity was measured by 4D PC-VIPR, peak velocity was measured by DUS, and flow volume (FV) of SMA and aorta were measured by 4D PC-VIPR and DUS 25 min before and after the peroral administration of TJ-100. The peak cross-sectionally averaged velocity, peak velocity, and FV of SMA measured by 4D PC-VIPR and DUS significantly increased after administration of TJ-100 (4D PC-VIPR: the peak cross-sectionally averaged velocity; p = 0.004, FV; p = 0.035, DUS: the peak velocity; p = 0.003, FV; p = 0.010). Furthermore, 4D PC-VIPR can analyze multiple blood vessels simultaneously. The ratio of the SMA FV to the aorta, before and after oral administration on the 4D PC-VIPR test also increased (p = 0.015). The rate of change assessed by 4D PC-VIPR and DUS were significantly correlated (the peak cross-sectionally averaged velocity and peak velocity: r = 0.650; p = 0.005, FV: r = 0.659; p = 0.004). Retrospective 4D PC-VIPR was a useful modality for morphological and hemodynamic analysis of SMA.