Nonenhanced MR Imaging Research Articles

Spatiotemporal knowledge teacher–student reinforcement learning to detect liver tumors without contrast agents

Detecting Liver tumors without contrast agents (CAs) has shown great potential to advance liver cancer screening. It enables the provision of a reliable liver tumor-detecting result from non-enhanced MR images comparable to the radiologists’ results from CA-enhanced MR images, thus eliminating the high risk of CAs, preventing an experience gap between radiologists and simplifying clinical workflows. In this paper, we proposed a novel spatiotemporal knowledge teacher–student reinforcement learning (SKT-RL) as a safe, speedy, and inexpensive contrast-free technology for liver tumor detection. Our SKT-RL builds a teacher–student framework to realize the exploring of explicit liver tumor knowledge from a teacher network on clear contrast-enhanced images to guide a student network to detect tumors from non-enhanced images directly. Importantly, our STK-RL enables three novelties in aspects of construction, transferring, and optimization to tumor knowledge to improve the guide effect. (1) A new spatiotemporal ternary knowledge set enables the construction of accurate knowledge that allows understanding of DRL’s behavior (what to do) and reason (why to do it) behind reliable detection within each state and between their related historical states. (2) A novel pixel momentum transferring strategy enables detailed and controlled knowledge transfer ability. It transfers knowledge at a pixel level to enlarge the explorable space of transferring and control how much knowledge is transferred to prevent over-rely of the student to the teacher. (3) A phase-trend reward function designs different evaluations according to different detection phases to optimal for each phase in high-precision but also allows reward trend to constraint the evaluation to improve stability. Comprehensive experiments on a generalized liver tumor dataset with 375 patients (including hemangiomas, hepatocellular carcinoma, and normal controls) show that our novel SKT-RL attains a new state-of-the-art performance (improved precision by at least 4% when comparing the six recent advanced methods) in the task of liver tumor detection without CAs. The results proved that our SKT-DRL has greatly promoted the development and deployment of contrast-free liver tumor technology.

SDPS-26 UNINTENDED RADIOTHERAPY DOSE ON THE NEUROGENIC NICHES IS ASSOCIATED WITH DECREASED OVERALL SURVIVAL IN PATIENTS WITH LUNG CANCER BRAIN METASTASES

Abstract INTRODUCTION Radiotherapy is the primary local intervention for cerebral metastases (BMs). Despite decades of advancements in this field, inadvertent collateral irradiation of adjacent healthy tissue in proximity to neoplastic site remains a persistent challenge. Neural stem cells (NSCs), crucial for the establishment and preservation of the nervous system, exhibit heightened sensitivity to radiation. Consequently, radiation-induced damage to NSCs may influence Overall Survival (OS) in patients with BMs. NSCs are primarily located in the subventricular zone (SVZ) and the subgranular zone (SGZ) within the hippocampus (HPC). In this study, our objective is to assess the influence of unintended radiotherapy dose on NSCs and its subsequent effect on OS. METHODS In this retrospective study, we incorporated data from 138 Non-Small Cell Lung Cancer (NSCLC) patients with BMs, from a single academic institution. NSC regions were projected on non-enhanced T1 MR images with Computational Anatomy Toolbox 12 and Statistical Parametric Mapping. The association between regional mean doses to the SVZ and HPC and OS was examined using a Cox regression model. Additionally, survival differences between lesion contact and no direct contact with SVZ and HPC were investigated with Kaplan-Meier (KM) analysis. RESULTS Multivariable Cox regression analysis of the dose on the SVZ and HPC showed a significant negative correlation, with a hazard ratio (HR) of 1.366 (p = 0.041 [95% (CI) 1.013– 1.842]) and 1.194 (p = 0.037 [95% CI 1.010 – 1.411]), respectively. KM analysis did not identify a relationship between direct lesion contact with NSC-regions and OS. CONCLUSION Any unintended dose on the neurogenic niches is correlated with poorer OS in patients with BMs from NSCLC. Interestingly, there was no association between direct contact or invasion of these regions and the OS. We recommend conducting further investigation into the impact on neurocognitive function within this specific group in a prospective study design.

Diagnostic performance and interreader agreement of individual and combined non-enhanced and contrast-enhanced MR imaging parameters in adhesive capsulitis of the shoulder

ObjectiveThe aims of our study were to analyze agreement among readers with different levels of expertise and diagnostic performance of individual and combined imaging signs for the diagnosis of adhesive capsulitis of the shoulder.MethodsIn a retrospective study, contrast-enhanced shoulder MRIs of 60 patients with and 120 without clinically diagnosed adhesive capsulitis were evaluated by three readers independently. As non-enhanced imaging signs, readers evaluated signal intensity and thickness of the axillary recess capsule, thickness of the rotator interval capsule and the coracohumeral ligament as well as obliteration of subcoracoid fat. Furthermore, contrast enhancement of axillary recess and rotator interval capsule were evaluated. Data analysis included interreader reliability, ROC analysis, and logistic regression (p < 0.05).ResultsContrast-enhanced parameters showed substantially higher agreement among readers (ICC 0.79–0.80) than non-enhanced parameters (0.37–0.45). AUCs of contrast-enhanced signs (95.1–96.6%) were significantly higher (p < 0.01) than of non-enhanced imaging signs (61.5–85.9%) when considered individually. Combined evaluation of axillary recess signal intensity and thicknesses of axillary recess or rotator interval—when at least one of two signs was rated positive—increased accuracy compared to individual imaging signs, however not statistically significant.ConclusionContrast-enhanced imaging signs show both distinctly higher agreement among readers and distinctly higher diagnostic performance compared to non-enhanced imaging signs based on the imaging protocol used in this study. Combined evaluation of parameters showed a tendency to increase discrimination; however, the effect on diagnosis of ACS was not statistically significant.

Applying Cross-Modality Data Processing for Infarction Learning in Medical Internet of Things

Cross-modality data processing is critical for the Internet-of-Things (IoT) deployment in healthcare. It can convert the innumerable raw day-to-day medical big data from massive IoT-based medical devices to diagnostic valuable data so that they can be feed to clinical routine. In this article, we propose a novel spatiotemporal two-streams generative adversarial network (SpGAN) as a cross-modality data processing approach to deploy the medical IoT in infarction learning. Our SpGAN remotely converts diagnostic valuable contrast-enhanced images (the “gold standard” for infarction learning, but it requires the injection of contrast agents) directly from raw nonenhanced cine MR images. This converting allows physicians to remotely perform infarction observation and analysis to break through the limitations of time and space by building a cloud computing platform of IoT-based MRI devices. Importantly, this converting offers a low-risk IoT-based manner to eliminate the potential fatal risk caused by contrast agent injection in the current infarction learning workflow. Specifically, SpGAN consists of: 1) a spatiotemporal two-stream framework as an encoding–decoding model to achieve data converting and 2) a spatiotemporal pyramid network enhances those features that are responsible to the infarction learning during encoding to improve decoding performance. Real IoT-based remote diagnosis experiments performed on 230 patients demonstrate that SpGAN provides high-quality converted images for infarction learning and promotes the in-depth application and deployment of IoT in the medical field.

Synthesis of gadolinium-enhanced liver tumors on nonenhanced liver MR images using pixel-level graph reinforcement learning.

If successful, synthesis of gadolinium (Gd)-enhanced liver tumors on nonenhanced liver MR images will be critical for liver tumor diagnosis and treatment. This synthesis will offer a safe, efficient, and low-cost clinical alternative to eliminate the use of contrast agents in the current clinical workflow and significantly benefit global healthcare systems. In this study, we propose a novel pixel-level graph reinforcement learning method (Pix-GRL). This method directly takes regular nonenhanced liver images as input and outputs AI-enhanced liver tumor images, thereby making them comparable to traditional Gd-enhanced liver tumor images. In Pix-GRL, each pixel has a pixel-level agent, and the agent explores the pixels features and outputs a pixel-level action to iteratively change the pixel value, ultimately generating AI-enhanced liver tumor images. Most importantly, Pix-GRL creatively embeds a graph convolution to represent all the pixel-level agents. A graph convolution is deployed to the agent for feature exploration to improve the effectiveness through the aggregation of long-range contextual features, as well as outputting the action to enhance the efficiency through shared parameter training between agents. Moreover, in our Pix-GRL method, a novel reward is used to measure pixel-level action to significantly improve the performance by considering the improvement in each action in each pixel with its own future state, as well as those of neighboring pixels. Pix-GRL significantly upgrades the existing medical DRL methods from a single agent to multiple pixel-level agents, becoming the first DRL method for medical image synthesis. Comprehensive experiments on three types of liver tumor datasets (benign, cancerous, and healthy controls) with 325 patients (24,375 images) show that our novel Pix-GRL method outperforms existing medical image synthesis learning methods. It achieved an SSIM of 0.85 ± 0.06 and a Pearson correlation coefficient of 0.92 in terms of the tumor size. These results prove that the potential exists to develop a successful clinical alternative to Gd-enhanced liver MR imaging.

Endoscope-assisted fluorescence-guided resection allowing supratotal removal in glioblastoma surgery.

Several studies have proven the benefits of a wide extent of resection (EOR) of contrast-enhancing tumor in terms of progression-free survival (PFS) and overall survival (OS) in patients with glioblastoma (GBM). Thus, gross-total resection (GTR) is the main surgical goal in noneloquently located GBMs. Complete tumor removal can be almost doubled by microscopic fluorescence guidance. Recently, a study has shown that an endoscope with a light source capable of inducing fluorescence allows visualization of remnant fluorescent tumor tissue even after complete microscopic fluorescence-guided (FG) resection, thereby increasing the rate of GTR. Since tumor infiltration spreads beyond the borders of contrast enhancement on MRI, the aim of this study was to determine via volumetric analyses of the EOR whether endoscope-assisted FG resection enables supratotal resection beyond the borders of contrast enhancement. The authors conducted a retrospective single-center analysis of a consecutive series of patients with primary GBM presumed to be noneloquently located and routinely operated on at their institution between January 2015 and February 2018 using a combined microscopic and endoscopic FG resection. A 20-mg/kg dose of 5-aminolevulinic acid (5-ALA) was administered 4 hours before surgery. After complete microscopic FG resection, the resection cavity was scanned using the endoscope. Detected residual fluorescent tissue was resected and embedded separately for histopathological examination. Nonenhanced and contrast-enhanced 3D T1-weighted MR images acquired before and within 48 hours after tumor resection were analyzed using 3D Slicer. Bias field-corrected data were used to segment brain parenchyma, contrast-enhancing tumor, and the resection cavity for volume definition. The difference between the pre- and postoperative brain parenchyma volume was considered to be equivalent to the resected nonenhancing but fluorescent tumor tissue. The volume of resected tumor tissue was calculated from the sum of resected contrast-enhancing tumor tissue and resected nonenhancing tumor tissue. Twelve patients with GBM were operated on using endoscopic after complete microscopic FG resection. In all cases, residual fluorescent tissue not visualized with the microscope was detected. Histopathological examination confirmed residual tumor tissue in all specimens. The mean preoperative volume of brain parenchyma without contrast-enhancing tumor was 1213.2 cm3. The mean postoperative volume of brain parenchyma without the resection cavity was 1151.2 cm3, accounting for a mean volume of nonenhancing but fluorescent tumor tissue of 62.0 cm3. The mean relative rate of the overall resected volume compared to the contrast-enhancing tumor volume was 244.7% (p < 0.001). Combined microscopic and endoscopic FG resection of GBM significantly increases the EOR and allows the surgeon to achieve a supratotal resection beyond the borders of contrast enhancement in noneloquently located GBM.

MRI texture analysis as a predictor of tumor recurrence or progression in patients with clinically non-functioning pituitary adenomas.

There are limited predictors of prognosis in patients with clinically non-functioning pituitary adenomas (NFPAs). We hypothesized that MRI texture analysis may predict tumor recurrence or progression in patients with NFPAs undergoing transsphenoidal pituitary surgery (TSS). To characterize texture parameters on preoperative MRI examinations in patients with NFPAs in relation to prognosis. Retrospective study of patients with NFPAs who underwent TSS at our institution between 2009 and 2010. Clinical, radiological and histopathological data were extracted from electronic medical records. MRI texture analysis was performed on coronal T1-weighted non-enhanced MR images using ImageJ (NIH). MRI texture parameters were used to predict tumor recurrence or progression. Both logistic regression and Cox proportional hazard analyses were conducted to adjust for potential confounders. Data on 78 patients were analyzed. On both crude and multivariable-adjusted analyses, mean, median, mode, minimum and maximum pixel intensity were associated with the risk of pituitary tumor recurrence or progression after TSS. Patients whose tumor mean pixel intensity was above the median for the population had a hazard ratio of 0.44 (95% CI: 0.21-0.94, P = 0.034) for recurrence or progression in comparison with tumors below the median. Our data suggest that MRI texture analysis can predict the risk of tumor recurrence or progression in patients with NFPAs.

Non-enhanced MR imaging for preinterventional assessment of the angioarchitecture in vein of Galen malformations

Background and purposeEndovascular treatment of vein of Galen malformations (VGMs) requires sufficient preceding MR imaging. Standardized, preinterventional, non-invasive imaging has not been established. Our study is the first to examine...

The quantitative analysis of MR dynamic contrast-enhangced imaging on efficacy and prognosis of transcatheter arterial chemoembolization on hepatocellular carcinoma

Objective: To investigate the prognostic value of quantitative parameters of dynamic contrast-enhangced MR (DCE-MR) on short-term efficacy of transcatheter arterial chemoembolization (TACE) on hepatocellular carcinoma(HCC). Methods: 79 patients with HCC underwent non-enhanced MR imaging and DCE on a 3.0T MR scanner before and one month after TACE. The quantitative parameters were measured on the maximal tumor region, including maximal tumor diameter(MTD), ADC, K(trans,) K(ep) and V(e) value before and after TACE. All patients were divided into stable group (36 patients) and progressive group (43 patients) based on follow-up. The quantitative data of the two groups before and after TACE was collected for analysis. Results: Among the 79 lesions in 79 patients, 21 were located in the left lobe of the liver, 53 in the right lobe of the liver and 5 in the junction area of the hepatic lobe. The maximum tumor diameter (MTD) was 2.2-9.9 cm, the median MTD was 5.1 cm. There were significant differences between progressive group and the stable group in MTD, K(trans,) K(ep) values of the tumor before TACE (P<0.05). One month after TACE, the MTD, K(trans,) K(ep,)ΔMTD, ΔK(trans) and ΔK(ep) values of the tumor in progressive group were statistically different with the stable group (P<0.05, respectively). For all the patients, the pre-TACE MTD, AFP, K(trans) and K(ep) values of tumors were statistically different with the post-TACE values (P<0.05). Conclusion: The quantitative parameters (K(trans,) K(ep,)ΔK(trans) and ΔK(ep) values) of the DCE-MR could predict and evaluate the short-term efficacy of TACE on HCC.

Elbow Imaging in Sport: Sports Imaging Series.

HomeRadiologyVol. 280, No. 1 PreviousNext CommunicationsFree AccessErrataElbow Imaging in Sport: Sports Imaging SeriesMatthew D. Bucknor, Kathryn J. Stevens, Lynne S. SteinbachMatthew D. Bucknor, Kathryn J. Stevens, Lynne S. SteinbachMatthew D. BucknorKathryn J. StevensLynne S. SteinbachPublished Online:Jun 20 2016https://doi.org/10.1148/radiol.2016164015MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In Originally published in:Radiology 2016;279(1):12–28 DOI: 10.1148/radiol.2016150501Erratum in:Radiology 2016;280(1):328 DOI:10.1148/radiol.2016164015The institutional affiliation for Kathryn J. Stevens should be as follows: Department of Radiology, Stanford University School of Medicine, Stanford, Calif.Article HistoryPublished online: June 20 2016Published in print: July 2016 FiguresReferencesRelatedDetailsCited ByMRI of the Upper ExtremityEira S.Roth, LuluHe2022Ossification of the posterior capitellum: description of a new pathology and its radiological appearanceM. M.Schneider, B.Hollinger, A.Zimmerer, R.Nietschke, H.Michaely, F.Migliorini, N.Maffulli, K. J.Burkhart2022 | Archives of Orthopaedic and Trauma SurgeryMRI of the Elbow: Interpretation of Common Orthopaedic InjuriesRupert O.Stanborough, Daniel E.Wessell, Bassem T.Elhassan, Bradley S.Schoch2022 | Journal of the American Academy of Orthopaedic Surgeons, Vol. 30, No. 6Acute elbow dislocation: comparison between magnetic resonance imaging and intra-operative finding of ligament injuryLuigiTarallo, GiovanniMerolla, GiuseppePorcellini, Maria GraziaAmorico, GianmarioMicheloni, MicheleNovi, EttoreDi Giovine, FabioCatani2021 | International Orthopaedics, Vol. 45, No. 1Pediatric Musculoskeletal Trauma: Special ConsiderationsJessica RLeschied, Steven BSoliman2021 | Seminars in Roentgenology, Vol. 56, No. 1Sports-related Fractures, Dislocations and TraumaJackSpittler, AdamSeidl2020Sports-related Fractures, Dislocations and TraumaJordan S.Gold, Adam C.Zoga, John C.Hill2020Postoperative Imaging of Sports InjuriesDavid A.Rubin2020Magnetic resonance imaging of elbow injuries in childrenNancy A.Chauvin, Cristy N.Gustas-French2019 | Pediatric Radiology, Vol. 49, No. 12Overuse Injuries of the ElbowArvin B.Kheterpal, Miriam A.Bredella2019 | Radiologic Clinics of North America, Vol. 57, No. 5Was erwarten Orthopäden und Unfallchirurgen vom Radiologen bei der Beurteilung der Bildgebung des Ellenbogens?R.Lenz, J.Bonacker, W.Mittelmeier, M.Ellenrieder, T.Tischer2018 | Der Radiologe, Vol. 58, No. 11Accompanying This ArticleElbow Imaging in Sport: Sports Imaging SeriesMar 18 2016RadiologyRecommended Articles MRI of the Normal Elbow and Common Pathologic ConditionsRadioGraphics2020Volume: 40Issue: 2pp. 468-469The Ulnar Nerve at Elbow Extension and Flexion: Assessment of Position and Signal Intensity on MR ImagesRadiology2016Volume: 280Issue: 2pp. 483-492Potential Utility of a Combined Approach with US and MR Arthrography to Image Medial Elbow Pain in Baseball PlayersRadiology2016Volume: 280Issue: 1pp. 328MRI-Arthroscopy Correlations: A Case-Based Atlas of the Knee, Shoulder, Elbow and HipRadiology2017Volume: 285Issue: 1pp. 34Histotopographic Anatomy of the Cubital TunnelRadiology2016Volume: 280Issue: 3pp. 979-980See More RSNA Education Exhibits A Useful Guide for Traumatic Elbow Injuries at Your ElbowDigital Posters2020High Resolution Ultrasonography (US) of the Elbow Demonstrating Standard Technique and Its Variations with Emphasis on Detailed Evaluation of Ligaments, Tendons, and NervesDigital Posters2019Dynamic Ultrasound and Guided Intervention in Cubital Tunnel Ulnar Nerve Subluxation - A Diagnosis Often OverlookedDigital Posters2018 RSNA Case Collection Medial epicondylar fracture with internal joint entrapmentRSNA Case Collection2022Supracondylar FractureRSNA Case Collection2020Radial Head FractureRSNA Case Collection2021 Vol. 280, No. 1 Metrics Altmetric Score PDF download

Hypervascular solid-appearing serous cystic neoplasms of the pancreas: Differential diagnosis with neuroendocrine tumours.

To describe imaging findings of arterial hypervascular solid-appearing serous cystic neoplasms (SCNs) of the pancreas on CT and MR and determine imaging features differentiating them from neuroendocrine tumours (NETs). We retrospectively identified 15 arterial hypervascular solid-appearing SCNs and randomly chose 30 size-matched pancreatic NETs. On CT, two radiologists in consensus assessed the size, morphology, and CT attenuation. On MR, predominant signal intensity and the amount of the cystic component on T2-weighted images and ADC maps were evaluated and compared using Fisher's exact and Student's t-test. The mean SCN size was 2.6 cm (range, 0.8-8.3). The CT findings were similar between the two tumours: location, shape, margin, and enhancement pattern. SCNs were significantly more hypodense on non-enhanced CT images than NETs (P = .03). They differed significantly on MR: bright signal intensity (P = .01) and more than a 10% cystic component on T2-weighted images (P = .01) were more common in SCNs than in NETs. All SCNs showed a non-restrictive pattern on the ADC map, while NETs showed diffusion restriction (P < .01). Arterial hypervascular solid-appearing SCNs and NETs share similar imaging features. Non-enhanced CT and MR images with T2-weighted images and ADC maps can facilitate the differentiation. • Frequency of hypervascular solid-appearing SCNs was 7.3% among surgically confirmed SCNs. • Hypervascular solid-appearing SCN of the pancreas can mimic pancreatic NETs. • Unenhanced CT and MR features help to differentiate the two tumours.

MRI manifestation of the knee in juvenile idiopathic arthritis and clinical relevance

Objective To semi-quantitatively assess the MRI manifestations of knee in patients with juvenile idiopathic arthritis (JIA) and to explore the relationship between the semi-quantitative scores with clinical inflammatory biomarkers. Methods Fifty children diagnosed as JIA and presented with knee pain, swelling or limitation were enrolled and their clinical and imaging findings were retrospectively analyzed. Contrast-enhanced MRI scan of the knee were performed in all cases (a total of 50 knees). MRI abnormalities, including synovial hypertrophy, joint effusion, bone marrow edema, joint cartilage injury and bone erosion, were assessed with a semi-quantitative score system. The erythrocyte sedimentation rate (ESR) and C reactive protein (CRP) at the same period with MRI were collected. The relationships between the MRI scores and laboratory biomarkers (CRP and ESR) were analyzed with Spearman correlation analysis. Results In MR images of all the 50 knees with JIA, synovial hypertrophy (43, 86%) and joint effusion (40, 80%)were major abnormalities, bone marrow edema was seen in 6 knees, joint cartilage injury in 12 knees and no bone erosion was seen. The scores of synovial hypertrophy, joint effusion, marrow edema, joint cartilage injury and bone erosion were 7 (0- 12), 3 (0- 7), 0 (0- 6), 0 (0- 10), 0, respectively. There was significant correlation between synovial hypertrophy and joint effusion (r=0.719, P=0.001). There were positive relationship between synovial hypertrophy and ESR and CRP (r=0.306 and 0.285; P=0.031 and 0.043, respectively).Other indexes had no significant relationship with ESR or CRP. Conclusions MRI could comprehensively evaluate knee involvement in patients with JIA. Joint effusion could be a useful reference to evaluate the condition of synovitis for pediatric patients with non-enhanced MR images. Key words: Arthritis ,juvenile rheumatoid; Magnetic resonance imaging; Knee joint

Detection of Artery Regions in Lower Extremity Arteries from Non-Enhanced MR Imaging Based on Particle Filter Algorithms

Recently, the arteries sclerosis obliterans (ASO) or called peripheral arterial disease (PAD) typically caused by chronic ischemia of limbs increases remarkably. As one of the diagnosis methods, the image diagnosis methods such as MR image are applied in medical fields. In this paper, we propose a vascular extraction method using fresh blood imaging (FBI) method, as well as apply it to computer aided diagnosis (CAD) system. Especially, to prevent the spread outside of the region and improve the segment accuracy of peripheral artery areas, we introduce particle filter algorithms. We performed our method on automatic artery regions detection using non-enhanced MR images. Furthermore, we compared the extracted results to gold standard data and analyzed accuracy by receiver operating characteristic (ROC). The effectiveness of our proposed method and satisfactory of its detected accuracy were confirmed.

New look at renal vasculature: 7 tesla nonenhanced T1‐weighted FLASH imaging

To investigate the feasibility of 7 Tesla (T) nonenhanced high field MR imaging of the renal vasculature and to evaluate the diagnostic potential of various nonenhanced T1-weighted (T1w) sequences. Twelve healthy volunteers were examined on a 7T whole-body MR system (Magnetom 7T, Siemens Healthcare Sector) using a custom-built eight-channel radiofrequency (RF) transmit/receive body coil. Subsequent to RF shimming, the following sequences were acquired (i) fat-saturated two-dimensional (2D) FLASH, (ii) fat-saturated 3D FLASH, and a (iii) fat-saturated 2D time-of-flight MR angiography (TOF MRA). SNR and CNR were measured in the aorta and both renal arteries. Qualitative analysis was performed with regard to vessel delineation (5-point scale: 5 = excellent to 1 = nondiagnostic) and presence of artifacts (5-point scale: 5 = no artifact present to 1 = strong impairment). The inherently high signal intensity of the renal arterial vasculature in T1w imaging enabled moderate to excellent vessel delineation in all sequences. Qualitative (mean, 4.7) and quantitative analysis (SNR(mean) : 53.9; CNR(mean) : 28.0) demonstrated the superiority of TOF MRA, whereas 2D FLASH imaging provided poorest vessel delineation and was most strongly impaired by artifacts (overall impairment 3.7). The 3D FLASH MRI demonstrated its potential for fast high quality imaging of the nonenhanced arterial vasculature, providing homogeneous hyperintense vessel signal. Nonenhanced T1w imaging in general and, TOF MRA in particular, appear to be promising techniques for good quality nonenhanced renal artery assessment at 7 Tesla.

112 MRIを用いた腰部脊髄・脊柱管の計測(GS1:診断・治療のバイオメカニクス)

112 MRIを用いた腰部脊髄・脊柱管の計測(GS1:診断・治療のバイオメカニクス)

Body diffusion-weighted MR imaging of uterine endometrial cancer: Is it helpful in the detection of cancer in nonenhanced MR imaging?

Objective In this study, the authors discussed the feasibility and value of diffusion-weighted (DW) MR imaging in the detection of uterine endometrial cancer in addition to conventional nonenhanced MR images. Methods and materials DW images of endometrial cancer in 23 patients were examined by using a 1.5-T MR scanner. This study investigated whether or not DW images offer additional incremental value to conventional nonenhanced MR imaging in comparison with histopathological results. Moreover, the apparent diffusion coefficient (ADC) values were measured in the regions of interest within the endometrial cancer and compared with those of normal endometrium and myometrium in 31 volunteers, leiomyoma in 14 patients and adenomyosis in 10 patients. The Wilcoxon rank sum test was used, with a p < 0.05 considered statistically significant. Results In 19 of 23 patients, endometrial cancers were detected only on T2-weighted images. In the remaining 4 patients, of whom two had coexisting leiomyoma, no cancer was detected on T2-weighted images. This corresponds to an 83% detection sensitivity for the carcinomas. When DW images and fused DW images/T2-weighted images were used in addition to the T2-weighted images, cancers were identified in 3 of the remaining 4 patients in addition to the 19 patients (overall detection sensitivity of 96%). The mean ADC value of endometrial cancer ( n = 22) was (0.97 ± 0.19) × 10 −3 mm 2/s, which was significantly lower than those of the normal endometrium, myometrium, leiomyoma and adenomyosis ( p < 0.05). Conclusion DW imaging can be helpful in the detection of uterine endometrial cancer in nonenhanced MR imaging.

Chronic Infection of a Seminal Vesicle Cyst as Depicted on MR Imaging

Chronic infection of a seminal vesicle cyst is an extremely rare disorder worldwide. To date, only two cases, which were diagnosed initially by the use of contrast-enhanced CT or non-enhanced MR imaging, have been reported in the literature. We report here a case of a 78-year-old man with chronic infection of a seminal vesicle cyst to illustrate the usefulness of the pelvic contrast-enhanced MRI in making a definitive diagnosis of the rare disorder. In addition, a brief review of the relevant literature is presented.

A Method for Detection of Blood Vessels from the Non-enhanced MR Imaging Employing Fresh Blood Imaging and Its 3-D Visualization

A Method for Detection of Blood Vessels from the Non-enhanced MR Imaging Employing Fresh Blood Imaging and Its 3-D Visualization

Prospective evaluation of nonenhanced MR imaging in acute pancreatitis

To compare the value of nonenhanced (NE) magnetic resonance imaging (MRI) (NE-MRI) with contrast-enhanced (CE) computed tomography (CT) (CE-CT) scan in assessing acute pancreatitis (AP) and in evaluating the severity index (SI) with clinical outcome. Patients with AP were prospectively investigated by CE-CT scan and NE-MRI on admission. MRI was performed with fat-saturated T1-weighted imaging, T2-weighted imaging, and MR cholangiopancreatography (MRCP). Balthazar's grading system was used to evaluate the NE-MRI severity index (CTSI, MRISI) and it was compared to the clinical outcome. A total of 90 patients (median age = 55 years) were included in the study. AP was of biliary etiology in 37 patients (41%). On admission, AP was assessed as grade III by CTSI in four patients (4%), whereas 19 patients were classified grade III by MRISI. The coefficient correlation between CTSI and MRISI was good, with r = 0.6 (P < 0.001). Considering CE-CT scan as the gold standard, sensitivity (Sn), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) of NE-MRI for detecting severe AP based on imaging criteria were 100%, 82.6%, 100%, and 21%, respectively. NE-MRI discriminates normal pancreatic parenchyma from edema and necrosis with a correlation between morbidity (P < 0.008). NE-MRI seems to be a reliable method of staging AP severity in comparison to CE-CT scan.

Characterization of Focal Brain Lesions by Gradient-Echo Arterial Spin-Tagging Perfusion Imaging

A simple gradient-echo arterial spin tagging (GREAST) technique allows for quick assessment of regional tissue perfusion without the need for exogenous contrast agent. The purpose of this prospective study was to validate GREAST imaging in characterizing the regional perfusion status of focal brain lesions by comparing with relative cerebral blood volume (rCBV) maps obtained by using echo-planar imaging (EPI)-based dynamic susceptibility contrast MR imaging. Thirty-two patients whose nonenhanced brain MR images showed 34 focal brain lesions during routine examination were selected to immediately undergo GREAST and dynamic susceptibility contrast MR imaging to evaluate regional perfusion of the lesions. The Pearson correlation coefficient was used to test the relative quantification of local perfusion with the two imaging methods. Qualitative perfusion measurements agreed in 23 (79%) of 29 lesions for which GREAST and dynamic susceptibility contrast MR imaging were successful. On rCBV maps, six focal lesions with local hemorrhage were underestimated. In three patients with metal surgical implants, lesions could not be measured because of susceptibility artifacts and distortion on EPIs. After these lesions were excluded, the Pearson correlation coefficient between relative quantitative perfusion measurements on GREAST images versus rCBV maps was about 0.90 (p value = 0.000). The success rate of GREAST imaging was 94% (30 of 32 patients), higher than that of dynamic susceptibility contrast MR imaging (72%, or 23 of 32 patients). GREAST imaging was comparable to rCBV mapping for the relative quantification of regional perfusion of focal brain lesions. This technique may be useful in routine MR examination for characterizing the regional perfusion of brain focal lesions.