Months Of Magnetic Resonance Imaging Research Articles

Association of structural MRI with Braak staging using neural network‐based risk scoring

AbstractBackgroundThe gold standard of Alzheimer’s disease (AD) diagnosis remains histopathologic examination of neuropathologic changes. However, the dependence on post‐mortem microscopic analysis limits the role of pathology in clinical care. Magnetic resonance imaging (MRI) is routinely used to diagnose suspected dementia (DE) due to AD, but correlating neuroimaging to underlying pathologic changes remains challenging. Herein, we report the development of two risk scores derived from convolutional neural network (CNN) processing of MRI scans, which we then validate against Braak staging of neurofibrillary tangles from autopsy reports.MethodUsing T1‐weighted MRIs from the National Alzheimer’s Coordinating Center (NACC), we trained two CNNs (Figure 1) to predict continuous scores for overall cognitive status (“COG” score) and AD probability (“ALZ” score). The COG score, ranging from 0‐2, graded a subject’s cognitive status on a spectrum from normal cognition (NC, 0), to mild cognitive impairment (MCI, 1), and DE due to any cause (2). The ALZ score then graded each DE individual’s probability of AD from 0 to 1. These CNNs were then applied to a subset of participants with autopsy reports available within 6 months of MRI. CNN performance was evaluated by area under receiver operating characteristic curve (AUC). Differences in risk scores were assessed by Kruskal‐Wallis H testing with post hoc Dunn testing.ResultThe CNN models for COG and ALZ score estimation were trained on 4,822 NACC participants. Thresholding of COG scores distinguished individuals with DE from those with NC and MCI (AUC = 0.87). ALZ scores distinguished individuals with AD from those with non‐AD causes of DE (AUC = 0.77). Among 74 persons with available neuropathology data, COG scores differed significantly among Braak staging groups (p<0.001), increasing from a mean of 0.99±0.36 in Stage 1 to 1.47±0.41 in Stage 6 (p = 0.010). Significant differences in ALZ scores were also observed (p = 0.039) between varying Braak stages (p = 0.039), increasing from a mean of 0.69±0.42 in Stage 1 to 0.91±0.29 in Stage 6 (p = 0.046) (Figure 2).ConclusionCNN processing of MRI scans may derive continuous risk scores for grading cognitive status and AD risk. This novel approach may offer practitioners a computational tool to improve AD diagnosis.

LI-RADS version 2018 for hepatocellular carcinoma < 1.0cm on gadoxetate disodium-enhanced magnetic resonance imaging.

We aimed to develop and evaluate a modified Liver Imaging Reporting and Data System (LI-RADS) version 2018 using significant ancillary features for diagnosing hepatocellular carcinoma (HCC) < 1.0cm on gadoxetate disodium-enhanced magnetic resonance imaging (MRI). Patients who underwent preoperative gadoxetate disodium-enhanced MRI for focal solid nodules < 2.0cm within 1month of MRI between January 2016 and December 2020 were retrospectively analyzed. Major and ancillary features were compared between HCCs of < 1.0cm and 1.0-1.9cm using the chi-square test. Significant ancillary features associated with HCC < 1.0cm were determined by univariable and multivariable logistic regression analysis. The sensitivity and specificity of LR-5 were compared between LI-RADS v2018 and our modified LI-RADS (applying the significant ancillary feature) using generalized estimating equations. Of 796 included nodules, 248 were < 1.0cm and 548 were 1.0-1.9cm. HCC < 1.0cm less frequently showed an enhancing capsule (7.1% vs. 31.1%, p < .001) and threshold growth (0% vs. 8.3%, p = .007) than HCC of 1.0-1.9cm. Restricted diffusion was the only ancillary feature significant for diagnosing HCC < 1.0cm (adjusted odds ratio = 11.50, p < .001). In the diagnosis of HCC, our modified LI-RADS using restricted diffusion had significantly higher sensitivity than LI-RADS v2018 (61.8% vs. 53.5%, p < .001), with similar specificity (97.3% vs. 97.8%, p = .157). Restricted diffusion was the only significant independent ancillary feature for diagnosing HCC < 1.0cm. Our modified LI-RADS using restricted diffusion can improve the sensitivity for HCC < 1.0cm. • The imaging features of hepatocellular carcinoma (HCC) < 1.0cm differed from those of HCC of 1.0-1.9cm. • Restricted diffusion was the only significant independent ancillary feature for HCC < 1.0cm. • Modified Liver Imaging Reporting and Data System (LI-RADS) with the addition of restricted diffusion can improve the sensitivity for HCC < 1.0cm.

Low Frequency Air-Bone Gap in Meniere's Disease: Relationship With Magnetic Resonance Imaging Features of Endolymphatic Hydrops.

Objectives:The appearance of low-frequency air-bone gaps (LFABGs) in Meniere’s disease (MD) is a recognized but relatively unexplored phenomenon. Two theories have been proposed to explain their etiology: increased perilymphatic pressure resulting in either reduced stapedial mobility or dampened transmission of acoustic energy, and direct contact between the dilated saccule and the stapes footplate. The aim of this study was to evaluate these two hypotheses by comparing delayed postgadolinium magnetic resonance imaging (MRI) features of two groups of patients with unilateral definite MD, those with and without LFABGs.Design:This retrospective case-control study was conducted at a tertiary otolaryngology unit in the United Kingdom. The study included 35 patients who satisfied the 2015 Barany criteria for unilateral definite MD. The cohort was divided into two groups, those with LFABGs (LFABG+ group) and those without (LFABG− group), according to the pure-tone audiometry performed within 6 months of MRI. Alternative potential causes for the LFABGs were excluded on the basis of otologic history, otoscopy, tympanometry, and/or imaging. Using a 4-hr delayed postgadolinium 3-dimensional fluid-attenuated inversion recovery sequence, two observers evaluated the severity of cochlear and vestibular endolymphatic hydrops (EH) and the presence of vestibular endolymphatic space contacting the oval window (VESCO). The air and bone conduction thresholds, ABGs and MRI features were compared between the LFABG+ and LFABG− groups. Where any of the variables were found to be significantly associated with the presence of ABGs, further analysis was performed to determine whether or not they were independent predictors. Continuous variables were compared using the independent t test if normally distributed, and the Mann–Whitney U test or Kruskall–Wallis test if not normally distributed. Categorical variables were compared with Pearson’s Chi-squared test or Fishers/Fisher-Freeman-Halton exact tests.Results:There were 10 patients in the LFABG+ group (28.6%) and 25 patients in the LFABG− group (71.4%). The mean ABGs in the symptomatic ear at 500 Hz, 1 kHz, and 2 kHz were 15.1 dB ± 6.4, 10.5 dB ± 9.0, and 4.0 dB ± 7.7, respectively, in the LFABG+ group and 2.0 ± 5.8, 2.4 ± 4.4, and −0.8 ± 4.7 dB in the LFABG− group. The differences in ABGs between the two groups were statistically significant at all three test frequencies (p < 0.001 at 500 Hz, p = 0.007 at 1 kHz, and p = 0.041 at 2 kHz). The presence of ABGs was significantly associated with both the grade of vestibular EH (p = 0.049) and VESCO (p = 0.009). Further analysis showed a statistically significant association between the grade of vestibular EH and VESCO (p = 0.007), and only VESCO was an independent variable associated with the presence of LFABGs (p = 0.045).Conclusions:The study findings add to the existing body of evidence that LFABGs are a true audiological finding in MD and allow us to propose a mechanism. Analysis of delayed gadolinium-enhanced MRI suggests that direct contact between the distended saccule and the inner surface of the stapes footplate is the more likely underlying pathophysiological mechanism for this audiometric phenomenon.

Accuracy of magnetic resonance imaging for meniscal body tear in anterior cruciate ligament-deficient knees compared to anterior cruciate ligament-intact knee

Objectives: This prospective case–control study was conducted with primary aim to compare the value of magnetic resonance imaging (MRI) in terms of accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for the detection of meniscal tear in anterior cruciate ligament (ACL)-deficient and ACL-intact groups. The secondary aim was to identify if the sensitivity and accuracy differ if the MRI is older than 3 months from the time of surgery. Materials and Methods: There were 255 patients enrolled into this study out of which 207 fulfilled the inclusion criteria. Among 207, 138 underwent surgery within 1 month of MRI, 30 had 1–3 months delay, and 39 cases underwent surgery more than 3 months after their MRI. Among 167 patients who underwent surgery within 3 months of MRI, 97 had ACL tear and 71 had intact ACL. Results: The overall sensitivity for lateral meniscus tear (68.2%) is significantly lower than the medial meniscus tear (92.9%). The sensitivity of MRI for medial meniscus tear in ACL-deficient knee is lower than ACL-intact knees (90% vs. 96.2%, P = 0.3). Similarly, the sensitivity is significantly lesser for lateral meniscus tear in ACL-deficient knee compared to ACL-intact knee (50% vs. 83.3%, P = 0.009). The sensitivity of MRI for both the lateral and medial meniscus tear decreased if the MRI performed 3 months before the surgery. Conclusion: Patients with ACL-deficient knee have to be counseled for intraoperative detection of lateral meniscus tear as the sensitivity of MRI for lateral meniscus tear in ACL-deficient group is low. Similarly, if the MRI is more than 3 months old from the time of surgery, we recommend to repeat the MRI as the sensitivity decreases significantly.

Real-time dynamic 3-T MRI assessment of spine kinematics: a feasibility study utilizing three different fast pulse sequences.

Half-Fourier acquisition single-shot turbo spin-echo (HASTE), continuous radial gradient-echo (GRE), and True FISP allow real-time dynamic assessment of the spine. To evaluate the feasibility of adding dynamic sequences to routine spine magnetic resonance imaging (MRI) for assessment of spondylolisthesis. Retrospective review was performed of patients referred for dynamic MRI of the cervical or lumbar spine between January 2017 and 2018 who had flexion-extension radiographs within two months of MRI. Exclusion criteria were: incomplete imaging; spinal hardware; and inability to tolerate dynamic examination. Blinded, independent review by two board-certified musculoskeletal radiologists was performed to assess for spondylolisthesis (>3 mm translation); consensus review of dynamic radiographs served as the gold standard. Cervical spinal cord effacement was assessed. Inter-reader agreement and radiographic concordance was calculated for each sequence. Twenty-one patients were included (8 men, 13 women; mean age 47.9 ± 16.5 years). Five had MRI of the cervical spine and 16 had MRI of the lumbar spine. Mean acquisition time was 18.4 ± 1.7 min with dynamic sequences in the range of 58-77 s. HASTE and True FISP had the highest inter-reader reproducibility (κ = 0.88). Reproducibility was better for the lumbar spine (κ = 0.94) than the cervical spine (κ = 0.28). Sensitivity of sequences for spondylolisthesis was in the range of 68.8%-78.6%. All three sequences had high accuracy levels: ≥90.5% averaged across the cervical and lumbar spine. Cervical cord effacement was observed during dynamic MRI in two cases (100% agreement). Real-time dynamic MRI sequences added to spine MRI protocols provide reliable and accurate assessment of cervical and lumbar spine spondylolisthesis during flexion and extension.

Surgical Ventricular Entry is a Key Risk Factor for Leptomeningeal Metastasis of High Grade Gliomas.

Leptomeningeal metastasis (LM) of high grade gliomas (HGG) can lead to devastating disease courses. Understanding of risk factors for LM is important to identify patients at risk. We reviewed patient records and magnetic resonance imaging (MRI) of all patients with a first diagnosis of HGG who underwent surgery in our institution between 2008 and 2012. To assess the influence of potential risk factors for LM and the impact of LM on survival multivariate statistics were performed. 239 patients with a diagnosis of HGG and at least 6 months of MRI and clinical follow-up were included. LM occurred in 27 (11%) patients and was symptomatic in 17 (65%). A strong correlation of surgical entry to the ventricle and LM was found (HR: 8.1). Ventricular entry was documented in 137 patients (57%) and LM ensued in 25 (18%) of these. Only two (2%) of 102 patients without ventricular entry developed LM. Median overall survival of patients after diagnosis of LM (239 days) was significantly shorter compared to patients without LM (626 days). LM is a frequent complication in the course of disease of HGG and is associated with poor survival. Surgical entry to the ventricle is a key risk factor for LM.

ENDORECTAL MAGNETIC RESONANCE IMAGING STAGING OF PROSTATE CANCER

There are important treatment and prognostic implications in distinguishing between organ-confined prostate cancer that has spread locally outside the capsule and that which has spread into the seminal vesicles. This study is the first Australian study to report local accuracy for the locoregional staging of prostate cancer with endorectal magnetic resonance imaging (MRI). From July 2002 to December 2005, 129 patients were referred for endorectal MRI for all indications. Inclusion criteria were biopsy-proven prostate cancer, minimum 4 weeks from previous biopsy and radical retropubic prostatectomy within 12 months of MRI. This yielded 47 patients. Those with prior hormonal and neoadjuvant radiotherapy or significant postbiopsy haemorrhage were excluded. In addition, those patients examined with our alternate-contrast-enhanced protocol were also excluded. A total of 38 patients met all inclusion criteria. A General Electric 1.5-T whole-body MR imaging unit with an endorectal coil was used with interpretation by two genito-urinary MR radiologists. Final histopathological report was used for correlation. Median age was 60 years with a range 44-72 years. Median prostate-specific antigen was 6.3 with a range of 2-82, and median Gleason score was 6 with a range of 5-8. Sensitivity, specificity and accuracy for extracapsular extension and seminal vesicle invasion were 69, 82 and 76% and 60, 100 and 95%, respectively. For extraprostatic extension, 71, 86 and 79%, respectively. Staging accuracy is similar to internationally published standards. Improvements in hardware and software and increased reader experience will add value to the local Australian prostate imaging programme.

Assessment of Right Ventricular Size and Function: Echo Versus Magnetic Resonance Imaging

The assessment of right ventricular (RV) size and function is important in the management of many patients with heart disease. Although magnetic resonance imaging (MRI) is considered the gold standard for quantitation of ventricular volumes and systolic function, subjective assessment ("eyeball") by echocardiography is the modality most often used for the RV. The echocardiographic "eyeball" method of assessing RV size and systolic function was compared with quantitative MRI. Patients with right-sided congenital heart disease who underwent an echocardiogram within 6 months of MRI formed the study group. Four echocardiographers blinded to the MRI results reviewed the echocardiograms to subjectively assess RV size and systolic function. The reliability of an echocardiographer in accurately identifying a severely dilated RV and moderately to severely diminished RV systolic function was measured using the Kappa coefficient. Inter-rater agreement was also assessed using Kappa. The study group consisted of 22 patients aged 16.6 +/- 7.1 years, with interval between MRI and echocardiogram of 49 +/- 54 days. Using echocardiography, reliability for accurately identifying a severely dilated RV was "slight" with a prevalence-adjusted bias-adjusted Kappa (PABAK) of 0.25; and for identifying moderately to severely diminished RV systolic function was fair with a PABAK of 0.43. Inter-rater agreement analysis was poor for both with Kappas of 0.07 (P = .22) and 0.12 (P = .09), respectively. The usefulness of the echocardiographic "eyeball" method to estimate RV size and systolic function in patients with right heart disease has limitations when compared with MRI, specifically in regard to the variability between echocardiographers.

Issue Highlights

HomeCirculationVol. 110, No. 16Issue Highlights Free AccessIn BriefPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessIn BriefPDF/EPUBIssue Highlights Originally published19 Oct 2004https://doi.org/10.1161/circ.110.16.2277Circulation. 2004;110:2277SELECTING PATIENTS WITH ATRIAL FIBRILLATION FOR ANTICOAGULATION: STROKE RISK STRATIFICATION IN PATIENTS TAKING ASPIRIN, by Gage et al.Quantifying a patient’s precise risk of ischemic stroke in atrial fibrillation is important for determining whether he or she would have a greater benefit from warfarin or aspirin. Gage and colleagues studied data from >2500 participants with nonvalvular atrial fibrillation who were entered into one of 6 large multicenter trials and determined the predictive accuracy of 5 distinct stroke risk stratification schemes. They found that all of the methods stratified the risk of stroke better than chance but that they varied widely in the number of patients who were identified as being at low or high risk. Although all of the schemes adequately identified the low-risk patients, success was variable for identification of the high-risk schemes. The authors conclude that a patient’s risk of stroke can be reliably identified and that this can guide the choice of antithrombotic agent. See p 2287.STATIN-INDUCED CHOLESTEROL LOWERING AND PLAQUE REGRESSION AFTER 6 MONTHS OF MAGNETIC RESONANCE IMAGING–MONITORED THERAPY, by Lima et al.In vivo monitoring of atherosclerosis regression has been challenging, as invasive imaging methods often have been used in the past. More recently, it has been demonstrated that magnetic resonance imaging can depict plaque area and volume, quantify lumen area, and allow an interrogation of plaque components. In this issue of Circulation, Lima and colleagues use a novel magnetic resonance technique combining standard magnetic resonance with an esophageal probe to obtain high-resolution images of the aortic wall and lumen. They demonstrate that plaque regression can be seen with 6 months of statin therapy and that the magnitude of plaque regression is related to the change in LDL cholesterol. This technique will enhance the ability to study the vascular changes that occur with aggressive lipid-lowering therapy and to delineate their time course. See p 2336.ASSOCIATIONS OF PARENTAL, BIRTH, AND EARLY LIFE CHARACTERISTICS WITH SYSTOLIC BLOOD PRESSURE AT AGE 5: FINDINGS FROM THE MATER-UNIVERSITY STUDY OF PREGNANCY AND ITS OUTCOMES, by Lawlor et al.Childhood blood pressure is likely to influence adult blood pressure and cardiovascular disease risk. In a cohort of 3864 children followed up prospectively from their mother’s first antenatal assessment to age 5 years, Lawlor and colleagues have shown that important determinants of blood pressure at age 5 years include body mass index of all family members, maternal age, maternal smoking during pregnancy, breastfeeding, and birth order. Because childhood blood pressure tracks into adulthood, interventions aimed at early-life risk factors, such as cessation of smoking during pregnancy and breastfeeding for at least 6 months, may be important for lowering blood pressure in the population and thus reducing cardiovascular disease risk. See p 2417.Visit www.circ.ahajournals.org:Cardiology Patient PagePrevention of Deep Vein Thrombosis and Pulmonary Embolism. See p e445.Images in Cardiovascular MedicineThrombosis of a Coronary Artery Aneurysm in a Young Man Presenting With Acute Myocardial Infarction. See p e448.Hypertrophic Cardiomyopathy with Apical Aneurysm. See p e450.Download figureDownload PowerPoint Previous Back to top Next FiguresReferencesRelatedDetails October 19, 2004Vol 110, Issue 16 Advertisement Article InformationMetrics https://doi.org/10.1161/circ.110.16.2277 Originally publishedOctober 19, 2004 PDF download Advertisement

Magnetic resonance imaging for diagnosis of pituitary macrotumors in dogs

Summary The value of magnetic resonance imaging (MRI) for the evaluation of dogs with pituitary-dependent hyperadrenocorticism (pdh) and cns signs was assessed. Magnetic resonance imaging of the brain was performed in 13 dogs with pdh and neurologic signs. The diagnosis of pdh was made on the basis of results of adrenocortical function tests and abdominal ultrasonography, in conjunction with appropriate history, clinical signs, and clinicopathologic alterations. Eight dogs had been treated with the adrenocorticolytic agent, mitotane, for 1 to 30 months before the development of neurologic signs. Prior to mri, each dog had progressive neurologic signs that could not be attributed to hypocortisolism or mitotane toxicosis. The neurologic signs most frequently detected were disorientation and ataxia. Mean age of dogs at the time neurologic signs developed was 9.5 years. Sex predilection was not detected; however, most were large-breed dogs, with 11 of the 13 dogs weighing more than 20 kg. A large mass in the pituitary gland, suprasellar region, or both was easily identified on the magnetic resonance images of each dog. The masses ranged from 8 to 24 mm in size. Expansion of tumors into the suprasellar region and compression of structures adjacent to the pituitary gland were readily detected by MRI. Contrast enhancement did not improve tumor identification, but did enable better delineation between tumor and surrounding structures. After the diagnosis of a macrotumor was made by MRI, radiotherapy was initiated in 9 dogs and was successfully completed in 6. Three dogs had a relapse of neurologic signs 8, 11, and 26 months after radiotherapy was completed. Three dogs are alive 8, 15, and 32 months after radiotherapy. Postmortem examinations performed on 7 dogs confirmed the diagnosis of pituitary macroadenomas. In 4 dogs, postmortem examination was performed within 1 month of MRI, providing a means to substantiate results. Magnetic resonance imaging provided accurate information on tumor size and the extent of tumor expansion into the surrounding structures.

Tetralogy of Fallot: MR findings.

Surgical treatment of patients with tetralogy of Fallot requires accurate definition of all anatomic structures, particularly the central pulmonary arteries. Magnetic resonance (MR) images of 22 patients with tetralogy of Fallot were studied to assess their usefulness in providing information regarding the spectrum of anatomic abnormalities in this condition. MR findings were compared with information obtained at catheterization (in 16 patients) and at surgery (in nine patients), both of which were performed within 3 months of MR imaging. Ventricular chamber enlargement and wall hypertrophy were clearly delineated in most of the 17 patients who were examined before definitive surgical repair, and ventricular septal defects were visualized in all 17. Palliative systemic-to-pulmonary shunts were visualized in 11 patients and could be evaluated for patency. Most important, the morphology and size of the right ventricular outflow tract and central pulmonary arteries could be accurately assessed. Pulmonary artery measurements obtained from MR images demonstrated excellent correlation with angiographic measurements. In six patients examined after complete surgical repair, MR images accurately reflected changes in pulmonary artery outflow tract morphology and complications, such as residual pulmonary artery stenosis and thrombosis. The findings suggest that MR imaging can complement or obviate catheterization in the evaluation of tetralogy of Fallot with regard to suitability for definitive surgical repair.