Unenhanced Magnetic Resonance Research Articles

Can combined tomosynthesis with unenhanced MRI be used as a predictive tool for lymphovascular invasion?

BackgroundThe presence of lymphovascular invasion (LVI) in cases with breast cancer is considered a bad prognostic sign. The purpose of this study is to compare the efficacy of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) versus unenhanced magnetic resonance imaging (UE-MRI + DBT) in predicting LVI in women with pathologically confirmed breast cancer.MethodsThis prospective self-controlled study enrolled a total of 70 cases of pathologically proven breast cancer. All the patients underwent tomosynthesis, non-contrast, and post-contrast MRI. Depending on the broken halo sign seen in tomosynthesis, peritumoral edema, dark rim diffusion at diffusion-weighted imaging (DWI), and apparent diffusion coefficient (ADC) values evaluated in MRI.ResultsThe accuracy of LVI detection by tomosynthesis was 58%; unenhanced and enhanced MRI had the same results at 60%. The accuracy of detecting LVI was raised to 64% by combining the tomosynthesis results with unenhanced MRI.ConclusionsTomosynthesis parameters are promising tools in detecting LVI in breast cancer with better diagnostic accuracy in combination with unenhanced MRI.

MRI-based lesion quality score assessing ossification of the posterior longitudinal ligament of the cervical spine

BACKGROUND CONTEXTNo method currently exists for MRI-based determination of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine using objective criteria. PURPOSEThe purpose of this study was to develop an MRI-based score to determine whether a lesion represents a cervical OPLL lesion and to establish the objective diagnostic value. STUDY DESIGNRetrospective cohort in a single medical institution. PATIENT SAMPLEThirty-five patients undergoing surgery for OPLL (Group A) and 99 patients undergoing cervical disc arthroplasty for soft disc herniation (Group B) between 2011 and 2020 were retrospectively included. All OPLL lesions on unenhanced MRI scan were correlated with a corresponding CT scan. Demographics were comparable between the two groups. OUTCOME MEASURES (PHYSIOLOGIC MEASURES)Using unenhanced magnetic resonance imaging (MRI), the T1- and T2- lesion quality (LQ) scores were calculated. Receiver operating characteristic (ROC) analysis was performed to calculate the area-under-the-curve (AUC) of both LQ scores as a predictor of the presence of OPLL. Computed tomography (CT)-based Hounsfield unit (HU) values of OPLL lesions were obtained and compared with both LQ scores. The LQ scores for MRI scanners from different manufacturers were compared using Student's t test to confirm the validity of the LQ score by scanner type. METHODSThe regions of interest for signal intensity (SI) were defined as the darkest site of the lesion and the cerebrospinal fluid (CSF) at the cerebellomedullary cistern. The T1 and T2 LQ scores were measured as the ratio of the SI at the darkest site of the lesion divided by the SI of the CSF. RESULTSThe T1 and T2 LQ scores in Group A were significantly lower than those in Group B (p<.001). ROC analysis determined that T1 and T2 LQ scores of 0.46 and 0.07, respectively, could distinguish the presence of OPLL with an accuracy of 0.93 and 0.89, respectively (p<.001). When the T1 LQ score of the lesion is <0.46, a diagnosis of OPLL may be suspected with 100% sensitivity and 92.3% specificity. The HU of the lesion had a moderate negative correlation with the T1 LQ score (r=−0.665, p<.0001). Both LQ scores were unaffected by manufacturer type. CONCLUSIONSThis study found a correlation between the MRI-based T1 LQ scores and CT-based HU value for identifying OPLL lesions. Additional studies will be needed to validate that the T1 LQ score from the unenhanced MRI scan can identify cervical OPLL.

Comparison of Fused Diffusion-Weighted Imaging Using Unenhanced MRI and Abbreviated Post-Contrast-Enhanced MRI in Patients with Breast Cancer.

Background and Objectives: To determine the percentage of breast cancers detectable by fused diffusion-weighted imaging (DWI) using unenhanced magnetic resonance imaging (MRI) and abbreviated post-contrast-enhanced MRI. Materials and Methods: Between October 2016 and October 2017, 194 consecutive women (mean age, 54.2 years; age range, 28-82 years) with newly diagnosed unilateral breast cancer, who underwent preoperative 3.0 T breast MRI with DWI, were evaluated. Both fused DWI and abbreviated MRI were independently reviewed by two radiologists for the detection of index cancer (which showed the most suspicious findings in both breasts), location, lesion conspicuity, lesion type, and lesion size. Moreover, the relationship between cancer detection and histopathological results of surgical specimens was evaluated. Results: Index cancer detection rates were comparable between fused DWI and abbreviated MRI (radiologist 1: 174/194 [89.7%] vs. 184/194 [94.8%], respectively, p = 0.057; radiologist 2: 174/194 [89.7%] vs. 183/194 [94.3%], respectively, p = 0.092). In both radiologists, abbreviated MRI showed a significantly higher lesion conspicuity than fused DWI (radiologist 1: 9.37 ± 2.24 vs. 8.78 ± 3.03, respectively, p < 0.001; radiologist 2: 9.16 ± 2.32 vs. 8.39 ± 2.93, respectively, p < 0.001). The κ value for the interobserver agreement of index cancer detection was 0.67 on fused DWI and 0.85 on abbreviated MRI. For lesion conspicuity, the intraclass correlation coefficients were 0.72 on fused DWI and 0.82 on abbreviated MRI. Among the histopathological factors, tumor invasiveness was associated with cancer detection on both fused DWI (p = 0.011) and abbreviated MRI (p = 0.004, radiologist 1), lymphovascular invasion on abbreviated MRI (p = 0.032, radiologist 1), and necrosis on fused DWI (p = 0.031, radiologist 2). Conclusions: Index cancer detection was comparable between fused DWI and abbreviated MRI, although abbreviated MRI showed a significantly better lesion conspicuity.

A Double-Stage 3D U-Net for On-Cloud Brain Extraction and Multi-Structure Segmentation from 7T MR Volumes

The brain is the organ most studied using Magnetic Resonance (MR). The emergence of 7T scanners has increased MR imaging resolution to a sub-millimeter level. However, there is a lack of automatic segmentation techniques for 7T MR volumes. This research aims to develop a novel deep learning-based algorithm for on-cloud brain extraction and multi-structure segmentation from unenhanced 7T MR volumes. To this aim, a double-stage 3D U-Net was implemented in a cloud service, directing its first stage to the automatic extraction of the brain and its second stage to the automatic segmentation of the grey matter, basal ganglia, white matter, ventricles, cerebellum, and brain stem. The training was performed on the 90% (the 10% of which served for validation) and the test on the 10% of the Glasgow database. A mean test Dice Similarity Coefficient (DSC) of 96.33% was achieved for the brain class. Mean test DSCs of 90.24%, 87.55%, 93.82%, 85.77%, 91.53%, and 89.95% were achieved for the brain structure classes, respectively. Therefore, the proposed double-stage 3D U-Net is effective in brain extraction and multi-structure segmentation from 7T MR volumes without any preprocessing and training data augmentation strategy while ensuring its machine-independent reproducibility.

Unenhanced magnetic resonance imaging of papillary thyroid carcinoma with emphasis on diffusion kurtosis imaging.

The aim of this study was to investigate the value of unenhanced magnetic resonance imaging (MRI) with diffusion kurtosis imaging (DKI) in diagnosing papillary thyroid carcinoma (PTC). In all, 77 consecutive patients comprising a total of 77 thyroid nodules were enrolled in this study. Of these nodules, 41 were histopathologically confirmed PTCs and 36 were benign nodules. All patients underwent thyroid MRI including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and DKI. All the images were assessed by 2 radiologists. The signal intensity ratio (SIR) of these nodules on T1WI and T2WI, the apparent diffusion coefficient (ADC) from DWI, and mean diffusivity (MD) and mean kurtosis (MK) from DKI were measured. Morphological features on these images were also evaluated. Univariate and multivariate logistic regression analyses were used to evaluate the value of these parameters as potential predictors of PTC. In the univariate analyses, the features that significantly indicated PTC were decreased ADC value (P<0.001), decreased MD value (P<0.001), increased MK value (P<0.001), younger age (P=0.001), female tendency (P=0.049), smaller tumor diameter (P<0.001), solid component (P<0.001), and irregular margin (P<0.001). In the multivariate analysis, decreased MD value (odds ratio =25.321; P=0.001), smaller diameter (odds ratio =13.751; P=0.006), and irregular margin (odds ratio =16.003; P=0.003) were independent risk factors for PTC. The combined predictor of MD, diameter, and margin showed an area under the receiver operating characteristic (ROC) curve of 0.996 in diagnosing PTC, with an optimal cutoff value of 0.69 (95.1% sensitivity, 100.0% specificity). Lower MD value from DKI, smaller diameter, and irregular margin are useful predictive biomarkers for PTC.

Development and validation of a MRI-based combined radiomics nomogram for differentiation in chondrosarcoma.

This study aims to develop and validate the performance of an unenhanced magnetic resonance imaging (MRI)-based combined radiomics nomogram for discrimination between low-grade and high-grade in chondrosarcoma. A total of 102 patients with 44 in low-grade and 58 in high-grade chondrosarcoma were enrolled and divided into training set (n=72) and validation set (n=30) with a 7:3 ratio in this retrospective study. The demographics and unenhanced MRI imaging characteristics of the patients were evaluated to develop a clinic-radiological factors model. Radiomics features were extracted from T1-weighted (T1WI) images to construct radiomics signature and calculate radiomics score (Rad-score). According to multivariate logistic regression analysis, a combined radiomics nomogram based on MRI was constructed by integrating radiomics signature and independent clinic-radiological features. The performance of the combined radiomics nomogram was evaluated in terms of calibration, discrimination, and clinical usefulness. Using multivariate logistic regression analysis, only one clinic-radiological feature (marrow edema OR=0.29, 95% CI=0.11-0.76, P=0.012) was found to be independent predictors of differentiation in chondrosarcoma. Combined with the above clinic-radiological predictor and the radiomics signature constructed by LASSO [least absolute shrinkage and selection operator], a combined radiomics nomogram based on MRI was constructed, and its predictive performance was better than that of clinic-radiological factors model and radiomics signature, with the AUC [area under the curve] of the training set and the validation set were 0.78 (95%CI =0.67-0.89) and 0.77 (95%CI =0.59-0.94), respectively. DCA [decision curve analysis] showed that combined radiomics nomogram has potential clinical application value. The MRI-based combined radiomics nomogram is a noninvasive preoperative prediction tool that combines clinic-radiological feature and radiomics signature and shows good predictive effect in distinguishing low-grade and high-grade bone chondrosarcoma, which may help clinicians to make accurate treatment plans.

Safe Follow-Up after Endovascular Aortic Repair with Unenhanced MRI: The SAFEVAR Study.

We aimed to investigate whether unenhanced magnetic resonance imaging (MRI) could represent a safe and highly sensitive tool for endoleak screening in patients treated with endovascular aneurysm repair (EVAR) using computed tomography angiography (CTA) as a reference standard. Patients who underwent CTA for EVAR follow-up at our institution were prospectively enrolled. All MRI examinations were performed with a 1.5 T unit. The true-FISP and HASTE sequences of the MRI scans were assessed for the presence of hyperintensity within the aneurysm sac outside the graft, whereas phase-contrast through-plane sequences were used for blood flow quantification. We included 45 patients, 5 (11%) of whom were female. The median age was 73 years (IQR 68−78 years). Among our patients, 19 (42%) were positive for endoleaks at CTA, of whom 13 (68%) had type II endoleaks and 6 (32%) had type I endoleaks. There were no significant differences in age, sex, aneurysm type, prosthesis type, or contrast-to-noise ratio between hyperintensity and thrombus between patients with and without endoleaks (p > 0.300). The combined evaluation of true-FISP and HASTE yielded 100% sensitivity (95% CI: 79−100%) and 19% specificity (95% CI: 7−40%). Patients with a positive CTA had a median thrombus flow of 0.06 L/min (IQR 0.03−0.23 L/min), significantly greater than that of patients with a negative CTA (p = 0.007). Setting a threshold at 0.01 L/min, our MRI protocol yielded 100% sensitivity, 56% specificity, and an AUC of 0.76 (95% CI 0.60−0.91). In conclusion, unenhanced MRI has perfect sensitivity for endoleak detection, although with subpar specificity that could be improved with phase-contrast flow analysis.

The influence of bone marrow edema for the assessment of the boundaries of necrotic lesions in patients with osteonecrosis of the femoral head

This study aimed to investigate the influence of bone marrow edema (BME) for the assessment of the boundaries of necrotic lesions using unenhanced and contrast-enhanced (CE) magnetic resonance (MR) images in patients with osteonecrosis of the femoral head (ONFH). We retrospectively reviewed 72 consecutive hips in 55 patients of ONFH that were Association Research Circulation Osseous (ARCO) stage III or higher and underwent both unenhanced and contrast-enhanced MR imaging between January 2005 and February 2016. The degree of extension of BMEs, and the boundaries of the necrotic lesions were compared using unenhanced and CE MR images on both mid coronal and mid oblique-axial slices. Forty-two percent of the coronal T1 images, 40% of the coronal fat-saturated T2 images, and 48% of the oblique-axial T1 images showed differences in the boundaries of necrotic lesion, by comparison with those of CET1-weighted MR images. The boundaries of necrotic lesions were clearly detected in all hips on CE coronal slices and 97% of all hips on CE oblique-axial slices. The BME grade in the difference group was significantly higher than in the non-difference group on the coronal plane (P = 0.0058). There were significant differences between the BME grade and duration from the onset of hip pain to MR imaging examination. Multivariate analyses revealed that the duration from the onset to MR imaging examination in both coronal (P = 0.0008) and oblique-axial slices (P = 0.0143) were independently associated with differences in the boundary of necrotic lesion between T1 and CET1-weighted MR images. Our findings suggest that unenhanced MR image may be insufficient for a precise assessment of the boundaries of the necrotic lesions for ONFH cases in the early phase of subchondral collapse due to the diffuse BME.

Multiconvolutional Transfer Learning for 3D Brain Tumor Magnetic Resonance Images.

The difficulty or cost of obtaining data or labels in applications like medical imaging has progressed less quickly. If deep learning techniques can be implemented reliably, automated workflows and more sophisticated analysis may be possible in previously unexplored areas of medical imaging. In addition, numerous characteristics of medical images, such as their high resolution, three-dimensional nature, and anatomical detail across multiple size scales, can increase the complexity of their analysis. This study employs multiconvolutional transfer learning (MCTL) for applying deep learning to small medical imaging datasets in an effort to address these issues. Multiconvolutional transfer learning is a model based on transfer learning that enables deep learning with small datasets. In order to learn new features on a smaller target dataset, an initial baseline is used in the transfer learning process. In this study, 3D MRI images of brain tumors are classified using a convolutional autoencoder method. In order to use unenhanced Magnetic Resonance Imaging (MRI) for clinical diagnosis, expensive and invasive contrast-enhancing procedures must be performed. MCTL has been shown to increase accuracy by 1.5%, indicating that small targets are more easily detected with MCTL. This research can be applied to a wide range of medical imaging and diagnostic procedures, including improving the accuracy of brain tumor severity diagnosis through the use of MRI.

T1 signal intensity in the dentate nucleus after the administration of the macrocyclic gadolinium-based contrast agent gadoterate meglumine: An observational study

Introduction and aimsContradictory results have been reported about hyperintensity of the globus pallidus and/or dentate nucleus on unenhanced T1-weighted magnetic resonance (MR) images after exposure to various gadolinium-based contrast agents. This change in signal intensity varies with different gadolinium-based contrast agents. We aimed to determine whether signal intensity in the dentate nucleus is increased in unenhanced T1-weighted images in patients who have undergone multiple studies with the macrocyclic gadolinium-based contrast agent gadoterate meglumine. We thoroughly reviewed the literature to corroborate our results. Materials and methodsWe included patients who had undergone more than 10 MR studies with gadoterate meglumine. We quantitatively analyzed the signal intensity in unenhanced T1-weighted MR images measured in regions of interest placed in the dentate nucleus and the pons, and we calculated the dentate nucleus-to-pons signal intensity ratios and the differences between the ratio in the first MR study and the last MR study. We used t-tests to evaluate whether the differences between the signal intensity ratios were different from 0. We also analyzed the subgroups of patients who had been administered <15 and ≥15 doses of gadoterate meglumine. We used Pearson correlation to determine the relationships between the differences in the signal intensity ratios and the number of doses of gadoterate meglumine administered. ResultsThe 54 patients (26 men) had received a mean of 13.8±3.47 doses (range, 10−23 doses). The difference in the dentate nucleus-pons signal intensity ratio between the first and last MR study was -0.0275±0.1917 (not significantly different from 0; p=0.2968) in the entire group, -0.0357±0.2204 (not significantly different from 0; p = 0.351 in the patients who had received <15 doses (n=34), and -0.0135±0.1332 (not significantly different from 0; p = 0.655) in those who had received ≥15 doses (n=20). Differences in signal intensity ratios did not correlate significantly with the accumulated dose of gadoterate meglumine (P = 0.9064; ρ = -0.0164 [95%]). ConclusionsReceiving more than 10 doses of gadoterate meglumine was not associated with increased signal intensity in the dentate nucleus.

Intravascular ultrasound correlation of unenhanced magnetic resonance venography in the context of pelvic deep venous disease

ObjectiveIn the present retrospective, assessor-blinded cross-sectional study, we compared the diagnostic efficacy of the relaxation-enhanced angiography without contrast and triggering (REACT) protocol for magnetic resonance venography (MRV) and intravascular ultrasound (IVUS). MethodsAll patients without prior lower limb vascular stenting who had undergone MRV with the REACT protocol and IVUS at our institution from January 2018 to May 2020 were included. The REACT protocol for MRV comprises three main phases: the adiabatic-based T2-preparation module, the non–volume-selective short tau inversion recovery pulse sequence, and the three-dimensional, modified two-point chemical-shift water-fat separated turbo-field echo pulse sequence. The IVUS findings served as the reference standard for stenosis and were used in the diagnostic efficacy analysis of the REACT protocol for MRV. The REACT protocol MRV images were reviewed by three board-certified interventional radiologists, and an interrater analysis was performed. ResultsA total of 33 patients (110 segments with IVUS correlation; 18 men [54.5%] and 15 women [45.5%]) were included. Most patients were Chinese (63.6%), and 24 had had bilateral deep venous disease (72.7%). The mean patient age was 59.0 years (range, 26.0-79.5 years). Moderate agreement was found between the three radiologists’ diagnoses of iliac vein pathology using the REACT protocol for MRV (κ = 0.524; 95% confidence interval [CI], 0.426-0.623; P < .001). Compared with IVUS, REACT protocol MRV achieved a sensitivity of 96.10% (95% CI, 89.03%-99.19%), specificity of 78.79% (95% CI, 61.09%-91.02%), positive predictive value of 91.36% (95% CI, 84.54%-95.33%), and negative predictive value of 89.66% (95% CI, 73.81%-96.38%). Overall, 78.5% agreement was noted between the REACT protocol MRV and IVUS findings. Good agreement between the index test and reference standard was noted (κ = 0.779; 95% CI, 0.645-0.907; P ≤ .05). ConclusionsREACT protocol MRV has the potential to be a highly sensitive and specific screening tool to diagnose deep venous disease.

Accuracy of Inflow Inversion Recovery (IFIR) for Upper Abdominal Arteries Evaluation: Comparison with Contrast-Enhanced MR and CTA.

Background: Inflow-sensitive inversion recovery (IFIR) is a recently introduced technique to perform unenhanced magnetic resonance angiography (MRA). The purpose of our study is to determine the accuracy of IFIR-MRA in the evaluation of upper abdominal arteries, compared to standard MRA and computed tomography angiography (CTA). Materials and Methods: Seventy patients undergoing upper abdomen Magnetic Resonance Imaging (MRI) in different clinical settings were enrolled. The MRI protocol included an IFIR-MRA sequence that was intra-individually compared by using a qualitative 4-point scale in the same patients who underwent concomitant or close MRA (n = 65) and/or CTA (n = 44). Celiac trunk (CA), common-proper-left-right hepatic artery (C-P-L-R-HA), left gastric artery (LGA), gastroduodenal artery (GDA), splenic artery (SA), renal arteries (RA) and superior mesenteric artery (SMA) were assessed. Results: IFIR-MRA images were better rated in comparison with MRA. Particularly, all arteries obtained a statistically significant higher qualitative rating value (all p < 0.05). IFIR-MRA and MRA exhibited acceptable intraclass correlation coefficients (ICC) values for CA, C-L-R-HA, and SMA (ICC 0.507, 0.591, 0.615, 0.570, 0.525). IFIR-MRA and CTA showed significant correlations in C-P-L-R-HA (τ = 0.362, 0.261, 0.308, 0.307, respectively; p < 0.05), and in RA (τ = 0.279, p < 0.05). Conclusions: Compared to MRA, IFIR-MRA demonstrated a higher image quality in the majority of upper abdomen arterial vessels assessment. LHA and RHA branches could be better visualized with IFIR sequences, when visualizable. Based on these findings, we suggest to routinely integrate IFIR sequences in upper abdomen MRI studies.

Unenhanced Cardiac Magnetic Resonance may improve detection and prognostication of an occult heart involvement in asymptomatic patients with systemic sclerosis

Systemic sclerosis (SSc) is an uncommon autoimmune disease. Aim of the study was to detect the occult cardiac involvement in asymptomatic SSc patients of recent onset (indicative of a more aggressive disease) with unenhanced Cardiac Magnetic Resonance (CMR). Our historical prospective study included naïve SSc patients of recent onset. Modified Rodnan Skin Score (mRSS) and Scleroderma Clinical Trial Consortium Damage Index (SCTC-DI) were calculated. Cardiac volumes and global myocardial strain were assessed and also compared with healthy group values. Pericardial involvement was further recorded. Thirty-one patients met inclusion criteria (54 ± 12 years; 1 M). Mean duration of disease was 6.8 years. All patients showed preserved systolic function. Higher incidence of pericardial involvement was founded in patients with disease accrual damage (OR: 9.6, p-value 0.01). Radial and longitudinal strain values resulted significantly different between healthy and SSc patients. GRS and GLS showed an independent predictive validity on damage accrual (HR: 1.22 and 1.47, respectively). Best C-index for disease progression was reached when strain values and pericardial evaluation were added to conventional risk factors (0.97, p-value: 0.0001). Strain analysis by CMR-TT may show a high capability both in identifying early cardiac involvement and stratifying its clinical aggressiveness, regardless of the standard damage indices and CMR contrast-dependent biomarker.

The role of magnetic resonance imaging in acute abdominal pain in paediatric age group

BackgroundThe purpose of this study is to evaluate the utility of magnetic resonance imaging in the assessment of acute atraumatic abdominal pain as the first line cross sectional modality in children, so as to prevent excessive radiation exposure from computed tomography scan and to review the magnetic resonance imaging features of common acute abdominal and pelvic conditions.Results30 patients (0–18 years) underwent rapid unenhanced magnetic resonance imaging. The results of our study indicated that for the diagnosis of causes for acute abdominal pain, magnetic resonance imaging had sensitivity of 92% (95% confidence interval 73.8–97.6%) and a specificity of 80% (95% confidence interval 28.4–99.5%). The positive predictive value was 95.8% (95% confidence interval 79.9–99.3%) and negative predictive value was 67% (95% confidence interval 33.1–89.0%) which had a highly significant statistical association (p < 0.001).ConclusionUnenhanced magnetic resonance imaging is an excellent option for the initial, detailed evaluation of acute abdominal emergencies in pediatric patients because it can diagnose the whole range of presenting abnormalities which include the causes of abdominal pain warranting surgical and nonsurgical management.

Unenhanced computed tomography for non-invasive diagnosis of hepatic steatosis with low tube potential protocol.

Lowering kVp affects the image contrast and computed tomography (CT) attenuation values of low kVp CT is different from those of conventional 120-kVp scans. The purpose of this study is to determine the diagnostic performance and to establish the reference range of low-kVp unenhanced CT for the assessment of hepatic steatosis in liver transplantation donors using magnetic resonance (MR) spectroscopy as a reference standard. This retrospective study included 165 potential donors (male:female =114:51, 36.5±12.0 years old) who underwent 100-kVp single-slice unenhanced CT scan and MR spectroscopy. The difference between hepatic and splenic attenuation (CTL-S) and liver-to-spleen attenuation ratio (CTL/S) were calculated. Reference standard was the fat signal fraction measured by MR spectroscopy. Limits of agreement between CT measurements and the reference standard were calculated. Areas under receiver operating characteristic curves (AUROCs) of CTL-S and CTL/S were compared for the diagnosis of moderate to severe steatosis. Cut-off values of CTL-S and CTL/S that provided a balance between sensitivity and specificity and the highest specificity using the lower limit of the reference range were calculated. Eighty-seven subjects had a non-steatotic liver. Sixty-one subjects had mild steatosis and 17 subjects had moderate to severe steatosis based on MR spectroscopy. CTL-S and CTL/S values were negatively correlated with the fat signal fraction (P<0.001) and limits of agreement were -8.4% to 8.4% for CTL-S and -9.6% to 9.6% for CTL/S. AUROCs of CTL-S and CTL/S for diagnosing moderate to severe steatosis were 0.956 and 0.957, respectively. Cut-off values of CTL-S and CTL/S for diagnosis of moderate to severe steatosis by the Youden index were -0.5 HU for CTL-S and 0.99 for CTL/S. Reference ranges of non-steatotic liver were -6.90 to 31.40 HU for CTL-S and 0.89 to 1.77 for CTL/S. Using -6.9 HU for CTL-S and 0.89 for CTL/S as cut-off values, the sensitivity and specificity for diagnosing moderate to severe steatosis were 70.59% and 90.54% (CTL-S) and 76.47% and 90.54% (CTL/S), respectively. Measurements from a low-kVp unenhanced CT scan were negatively correlated with the degree of hepatic steatosis. Low-kVp unenhanced CT is a robust technique with reduced radiation exposure for diagnosing moderate to severe hepatic steatosis.

Right adrenal vein identification using unenhanced magnetic resonance imaging.

Unenhanced magnetic resonance imaging (MRI) is known to be useful in characterizing adrenal adenomas through the implementation of in-phase (IPI) and opposed-phase imaging (OPI) based on chemical shift artifacts. However, whether unenhanced MRI can contribute to the identification of right adrenal vein (RAV) remains unclear. The aim of this study was to evaluate the feasibility of unenhanced MRI for the identification of RAV. This retrospective study reviewed 30 patients (16 men; median age 60 years; range 34-76 years) who underwent MRI and subsequent adrenal venous sampling (AVS). Chemical shift MRI was acquired using echo times of 2.3 ms (OPI) and 4.6 ms (IPI) with a slice thickness of 3 mm and a gap of 1 mm. T2-weighted imaging (T2WI) was also performed. Identification of RAVs was performed by 2 independent radiologists. Inter-observer agreement on a 3-point rating scale was evaluated using κ statistics. The identification rate of RAVs was compared between OPI, IPI, and T2WI using McNemar's test. Good inter-observer agreement was found for the OPI (κ = 0.744), whereas fair agreement was obtained for both other sequences (IPI: κ = 0.375; T2WI: 0.348). For both raters, the identification rate of RAVs was higher with OPI (36/60; 60.0%) than with other sequences (IPI: 16/60, 26.7%; T2WI: 9/60, 15.0%; p < 0.05, each). OPI may play a screening role in the identification of RAVs preceding AVS, which could reduce the required radiation exposure and doses of contrast agent.

Delayed Diplopia After Sports-Related Concussion: A Multidisciplinary Approach to Evaluation and Management

To highlight a multidisciplinary approach to the diagnosis and management of unilateral abducens palsy after a sports-related concussion. Mild traumatic brain injury (TBI) often leads to disruptions in visual functioning, affecting convergence, saccades, smooth pursuit, and accommodation. More severe TBI injuries may result in structural injuries to the ocular muscles, nerves, or the brain itself. NA. Case: We present the case of a 33-year-old male with unilateral abducens nerve palsy after a sports-related concussion with loss of consciousness and multiple hemorrhagic contusions. The patient's visual symptoms manifested several days after the injury. With a multi-disciplinary evaluation involving specialists representing neurosurgery, endovascular neurology and neuro-ophthamology, unenhanced magnetic resonance imaging revealed multiple foci of intraparenchymal microhemorrhages and siderosis consistent with diffuse axonal injury (DAI), and an incidental parasagittal cavernoma. The delayed development of a sixth nerve palsy raised our suspicion for secondary axotomy, as has been described following TBI. While the probability of recovery is high, close follow up is imperative to address evolution of the patient's symptoms. In this case, the patient developed imbalance and headaches in association with his visual symptoms. For the imbalance we use physical therapy with therapists trained in vestibular therapy and for the visual symptoms we use vision therapy with trained optometrists. Delayed post-traumatic abducens palsy is concerning for DAI and secondary axotomy. Multidisciplinary assessment imparts the ability to evaluate for all possible causes and provide additional specialized care for recovery.

Comparison of unenhanced magnetic resonance imaging and ultrasound in detecting very small hepatocellular carcinoma.

BACKGROUNDIn hepatocellular carcinoma (HCC), detection and treatment prior to growth beyond 2 cm are important as a larger tumor size is more frequently associated with microvascular invasion and/or satellites. In the surveillance of very small HCC nodules (≤ 2 cm in maximum diameter, Barcelona clinical stage 0), we demonstrated that the tumor markers alpha-fetoprotein and PIVKA-Ⅱ are not so useful. Therefore, we must survey with imaging modalities. The superiority of magnetic resonance imaging (MRI) over ultrasound (US) to detect HCC was confirmed in many studies. Although enhanced MRI is now performed to accurately diagnose HCC, in conventional clinical practice for HCC surveillance in liver diseases, unenhanced MRI is widely performed throughout the world. While, MRI has made marked improvements in recent years.AIMTo make a comparison of unenhanced MRI and US in detecting very small HCC that was examined in the last ten years in patients in whom MRI and US examinations were performed nearly simultaneously.METHODSIn 394 patients with very small HCC nodules, those who underwent MRI and US at nearly the same time (on the same day whenever possible or at least within 14 days of one another) at the first diagnosis of HCC were selected. The detection rate of HCC with unenhanced MRI was investigated and compared with that of unenhanced US.RESULTSThe sensitivity of unenhanced MRI for detecting very small HCC was 95.1% (97/102, 95% confidence interval: 90.9-99.3) and that of unenhanced US was 69.6% (71/102, 95% confidence interval: 60.7-78.5). The sensitivity of unenhanced MRI for detecting very small HCC was significantly higher than that of unenhanced US (P < 0.001). Regarding the location of HCC in the liver in patients in whom detection by US was unsuccessful, S7-8 was identified in 51.7%.CONCLUSIONCurrently, unenhanced MRI is a very useful tool for the surveillance of very small HCC in conventional clinical follow-up practice.

Preoperative Staging in Breast Cancer: Intraindividual Comparison of Unenhanced MRI Combined With Digital Breast Tomosynthesis and Dynamic Contrast Enhanced-MRI.

ObjectivesTo evaluate the accuracy in lesion detection and size assessment of Unenhanced Magnetic Resonance Imaging combined with Digital Breast Tomosynthesis (UE-MRI+DBT) and Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI), in women with known breast cancer.MethodsA retrospective analysis was performed on 84 patients with histological diagnosis of breast cancer, who underwent MRI on a 3T scanner and DBT over 2018-2019, in our Institution. Two radiologists, with 15 and 7 years of experience in breast imaging respectively, reviewed DCE-MRI and UE-MRI (including DWI and T2-w) + DBT images in separate reading sections, unaware of the final histological examination. DCE-MRI and UE-MRI+DBT sensitivity, positive predictive value (PPV) and accuracy were calculated, using histology as the gold standard. Spearman correlation and regression analyses were performed to evaluate lesion size agreement between DCE-MRI vs Histology, UE-MRI+DBT vs Histology, and DCE-MRI vs UE-MRI+DBT. Inter-reader agreement was evaluated using Cohen’s κ coefficient. McNemar test was used to identify differences in terms of detection rate between the two methodological approaches. Spearman’s correlation analysis was also performed to evaluate the correlation between ADC values and histological features.Results109 lesions were confirmed on histological examination. DCE-MRI showed high sensitivity (100% Reader 1, 98% Reader 2), good PPV (89% Reader 1, 90% Reader 2) and accuracy (90% for both readers). UE-MRI+DBT showed 97% sensitivity, 91% PPV and 92% accuracy, for both readers. Lesion size Spearman coefficient were 0.94 (Reader 1) and 0.91 (Reader 2) for DCE-MRI vs Histology; 0.91 (Reader 1) and 0.90 (Reader 2) for UE-MRI+DBT vs Histology (p-value <0.001). DCE-MRI vs UE-MRI+DBT regression coefficient was 0.96 for Reader 1 and 0.94 for Reader 2. Inter-reader agreement was 0.79 for DCE-MRI and 0.94 for UE-MRI+DBT. McNemar test did not show a statistically significant difference between DCE-MRI and UE-MRI+DBT (McNemar test p-value >0.05). Spearman analyses showed an inverse correlation between ADC values and histological grade (p-value <0.001).ConclusionsDCE-MRI was the most sensitive imaging technique in breast cancer preoperative staging. However, UE-MRI+DBT demonstrated good sensitivity and accuracy in lesion detection and tumor size assessment. Thus, UE-MRI could be a valid alternative when patients have already performed DBT.

Hemodynamic study of unenhanced magnetic resonance angiography using spatial labeling with multiple inversion pulses sequence: a phantom study.

This study sought to explore the functional relationship between displayed vascular length and blood suppression inversion time (BSP TI) and flow velocity in a phantom, and to provide a theoretical basis for quantitatively assessing vascular hemodynamic responses using unenhanced magnetic resonance angiography (MRA) and spatial labeling with multiple inversion pulses sequence (SLEEK). A polyethylene catheter was laid in a long rectangular container filled with pork fat. The entrance of the catheter into the container was connected to a high-pressure syringe filled with normal saline. The high-pressure injector flow rates were set at 0.0, 0.2, 0.4, 0.8, 1.2, 1.6, 2.0, and 2.4 mL/s. SLEEK was performed 19 times for each flow rate with parameter BSP TI values of 50, 75, 100, 150, 200, 300, 400, 500, 600, 700, 800, 900, 1,000, 1,100, 1,200, 1,300, 1,400, 1,600, and 1,800 ms. Maximum intensity projection was employed to reconstruct all SLEEK original images to determine the measurements of the displayed vascular lengths. A regression analysis was undertaken to assess the relationship between the displayed vascular lengths and BSP TI values for each flow rate, and to assess the relationship between the displayed vascular lengths and flow rates at each BSP TI. The displayed vascular length had a linear relationship with BSP TI for each flow rate (P<0.05) (R2=0.754, 0.941, 0.988, 0.988, 0.977, 0.966, and 0.982 for flow rates of 0.0, 0.2, 0.4, 0.8, 1.2, 1.6, and 2.0 mL/s, respectively). The displayed vascular length also had a linear relationship with flow rate for each BSP TI value (P<0.05) (R2 =0.914, 0.912, 0.834, 0.989, 0.980, 0.996, 0.992, 0.960, 0.975, 0.979, 0.982, 0.981, 0.976, and 0.993 for BSP TI 50, 75, 100, 150, 200, 300, 400, 500, 600, 700, 800, 900, 1,000, and 1,100 ms, respectively). No significant linear relationship was found between displayed vascular length and flow rate when the BSP TI value was 1,200 ms (P>0.05). Vascular displayed length has a linear relationship to BSP TI for flow ranges from 0.0 to 2.0 mL/s. Vascular displayed length has a linear relationship to flow rate for BSP TI values of 50 to 1,100 ms. Flow rate can be assessed in relation to vascular displayed length.