Diffusion-weighted imaging in patients with progressive multifocal leukoencephalopathy

Over the past few years, diffusion-weighted imaging (DWI) has become an increasingly important diagnostic tool in the diagnosis of liver lesions. The objective of the present study was to evaluate the diagnostic benefit of high b-value computed diffusion-weighted imaging (c-DWI) compared with standard DWI in patients with hepatocellular carcinoma (HCC) and whether there is an association with microvascular invasion (MVI). In total, 37 patients with histopathologically confirmed HCC were retrospectively ana-lyzed. DWI was acquired with b-values of 50, 400, and 800 or 1000 s/mm² on a 1.5 T magnetic resonance imaging (MRI) scanner. The c-DWI was calculated using a monoexponential model with high b-values of 1000, 2000, 3000, 4000, and 5000 s/mm². All high b-value c-DWI images were compared to the standard DWI in terms of volume, detectability of hepatic lesions, and image quality. Regarding lesion volume and image quality there were no statistically significant differences between standard and c-DWI. HCC lesions measured on DWI images were statistically significantly larger compared to c-DWI images starting from a b value of 2000 s/mm2 (DWI vs. c-DWI b 2000 s/mm2: 2 cm3 [1-12] cm3 vs. 1 cm3 [0-17] cm3, p < 0.05). Moreover, there was deterioration of image quality starting at b = 2000 s/mm2. There were no significant differences in terms of lesion signal intensity in DWI and c-DWI images. There were no differences for the DWI parameters according to MVI status. C-DWI images with high b-values up to b = 1000 s/mm2 demonstrate comparable detectability of HCC compared to standard DWI. The investigated DWI parameters were not associated with MVI status. Further research is needed to evaluate the potential benefit of high b-value c-DWI.

Diffusion-weighted imaging (DWI) has shown high sensitivity in the diagnosis of acute arterial strokes. The pathophysiology of cerebral venous thrombosis with associated venous stroke appears to differ from that of arterial strokes. The purpose of this study was to describe DWI findings in venous strokes. The authors reviewed 3 adults with superior sagittal sinus thrombosis who underwent DWI and magnetic resonance imaging within 24 hours of symptom onset. DWI was obtained at 1.5 T using the multishot echo planar technique (TR = 8000, TE = 97, field of view = 30 x 19 cm, slice thickness = 6.0 mm, interslice gap = 0.5 mm, matrix 128 x 128, NEX = 1). The diffusion gradients were applied in 3 orthogonal directions with 3 increasing b values (0-1000 s/mm2) to create average (trace) DWI images. Apparent diffusion coefficient (ADC) values were calculated on a pixel-by-pixel basis and displayed as ADC maps. DWI showed hyperintensities in patients 1 and 2 and hypointensity in patient 3 in corresponding to parenchymal lesions on conventional images. As compared to the homologous uninvolved location in the contralateral hemisphere, ADC values were decreased (0.53 x 10(-3) mm2/s [patient 1] and 0.68 x 10(-3) mm2/s [patient 2]) and increased (1.1 x 10(-3) mm2/s [patient 3]). The ADC ratio of the lesion in the involved to uninvolved side was 88% (patient 1), 81% (patient 2), and 120% (patient 3). Acute cerebral venous strokes may contain cytotoxic edema and/or vasogenic edema on DWI scans. DWI may be helpful in diagnosing cerebral venous thrombosis in cases with cryptic presentations.

Background: Several studies have shown that the majority of patients with simple appendicitis can be treated effectively and safely with antibiotics, avoiding unnecessary operation. Objectives: The objective of this study was to assess the role of diffusion-weighted imaging (DWI) in the follow-up of conservative treatment of simple appendicitis. Patients and Methods: Twenty-eight patients (mean age, 35 ± 14.6; age range, 18 - 72; M/F: 16/12) with simple appendicitis were enrolled in this prospective study. After the primary diagnosis by computed tomography (CT) at presentation, they underwent an initial DWI scan, and intravenous antibiotic therapy was started for all patients by the decision of the attending surgeon. A total of three control DWI scans were planned during the follow-up period for each patient. CT and DWI images were evaluated by two radiologists in consensus. B values 0, 500 and 1000 s/mm2 were used, and DWI images were analyzed both qualitatively and quantitatively. During follow-up, changes in the diameter of appendices and laboratory parameters were correlated with apparent diffusion coefficient (ADC) values. Results: We found statistically significant correlation between ADC values, maximum appendix diameter and laboratory parameters. During follow-up period four surgical procedures were performed for reccurent appendicitis. Conclusion: DWI may be used with a significant success for follow-up evaluation of patients with simple appendicitis. As a monitoring imaging method, DWI may also aid in determining the recurrences of appendicitis.

BackgroundAccurate segmentation of pelvic bones is an initial step to achieve accurate detection and localisation of pelvic bone metastases. This study presents a deep learning-based approach for automated segmentation of normal pelvic bony structures in multiparametric magnetic resonance imaging (mpMRI) using a 3D convolutional neural network (CNN).MethodsThis retrospective study included 264 pelvic mpMRI data obtained between 2018 and 2019. The manual annotations of pelvic bony structures (which included lumbar vertebra, sacrococcyx, ilium, acetabulum, femoral head, femoral neck, ischium, and pubis) on diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) images were used to create reference standards. A 3D U-Net CNN was employed for automatic pelvic bone segmentation. Additionally, 60 mpMRI data from 2020 were included and used to evaluate the model externally.ResultsThe CNN achieved a high Dice similarity coefficient (DSC) average in both testing (0.80 [DWI images] and 0.85 [ADC images]) and external (0.79 [DWI images] and 0.84 [ADC images]) validation sets. Pelvic bone volumes measured with manual and CNN-predicted segmentations were highly correlated (R2 value of 0.84–0.97) and in close agreement (mean bias of 2.6–4.5 cm3). A SCORE system was designed to qualitatively evaluate the model for which both testing and external validation sets achieved high scores in terms of both qualitative evaluation and concordance between two readers (ICC = 0.904; 95% confidence interval: 0.871–0.929).ConclusionsA deep learning-based method can achieve automated pelvic bone segmentation on DWI and ADC images with suitable quantitative and qualitative performance.

Diagnostic performance of multiparametric nonenhanced magnetic resonance imaging (MRI) in grading glioma and correlating IDH mutation status.

Cardiac troponin (hs-cTnT) is a sensitive marker of myocardial injury and has been linked to incident dementia. The underlying mechanism of that observation is still unknown. Given that severity of cerebral small vessel disease is a predictor of cognitive decline, we aimed to explore whether there is an association between hs-cTnT and severity of white matter lesions (WML) as a marker of cerebral small vessel disease in patients with ischemic stroke. We analyzed consecutive acute ischemic stroke patients admitted to Charité-University Hospital, Berlin from 2011 to 2013. Severity of WML was graded on 3T-MRI using the age-related white matter severity score (ARWMS). Patients with hs-cTnT elevation suggestive of acute coronary syndrome (ACS) were excluded (hs-cTnT > 52ng/l or dynamic change of hs-cTnT > 50%, ESC guideline). We performed unadjusted and adjusted quantile regression models to assess the association between increased hs-cTnT (dichotomized at the 99th percentile, 14ng/l) and severity of WML. A total of 860 patients was analyzed (median age 73years, 44.8% female, median ARWMS 6). Patients with elevated hs-cTnT had more extensive WML than those without (median ARWMS 8 vs. 5, adjusted beta for 50th percentile 1.12, 95% CI 0.41-1.84). The association between WML and hs-cTnT elevation was strongest in patients with severe WML (adjusted beta 1.77, 95% CI 0.26-3.27 for 80th WML percentile). Elevated hs-cTnT levels were associated with extent of WML in acute stroke patients. Further studies are needed to assess whether hs-cTnT can be used to identify stroke patients at risk for cognitive decline.

Primary objective: Cerebral oedema is a common complication of traumatic brain injury (TBI). The use of Fluid-Attenuated Inversion Recovery (FLAIR) imaging in combination with Diffusion Weighted Imaging (DWI) has the potential to distinguish between cytotoxic and vasogenic oedema. This study hypothesized a significant relationship between cytotoxic lesion volume and outcome.Research design: This observational study reports on a convenience sample where MRI was obtained for clinical purposes.Methods and procedures: Clinical post-TBI FLAIR and DWI images were analysed. For this study, lesions were defined as primarily cytotoxic oedema if the ratio of FLAIR to DWI lesion volume was comparable, defined as a ratio <2. If the ratio of FLAIR to DWI lesion volume was ≥2, oedema was considered predominantly of vasogenic origin.Main outcomes and results: The sample consisted primarily of males with TBIs whose injury severity ranged from complicated mild to severe. Analysis revealed that both oedema types are common after TBI and both are associated with functional deficits 6 months after injury.Conclusions: Acute MRI may be useful to assess pathology at the tissue after traumatic brain injury. Clinical trials targeting cytotoxic and vasogenic mechanisms of oedema formation may benefit from using DWI and FLAIR MRI as a means to differentiate the predominant oedema type after TBI.

Progressive multifocal leukoencephalopathy (PML) is a serious disorder that primarily affects individuals with a suppressed immune system. Few semiological elements help clearly distinguish PML from other diseases included in the differential diagnosis. Moreover, the clinical course of disease may be chronic or rapidly progressive, with different magnetic resonance imaging (MRI) patterns. The purpose of this study was to confirm the diagnostic value of conventional MRI sequences combined with diffusion-weighted imaging (DWI) in PML to identify those patients with worst prognosis. We used both conventional MRI sequences and DWI to monitor four male patients aged between 40 and 50 years affected by PML. In two patients, the disease rapidly led to death whereas the other two patients presented a chronic course. Conventional MRI sequences enable detection of the extension of white matter lesions. DWI permits more accurate differentiation of the disease progression front, which exhibits low signal intensity in apparent diffusion coefficient (ADC) maps, from the central gliotic area of demyelinisation, characterised by high ADC values. Patients with rapidly evolving PML have a clear progression front on DWI, which seems to be very tenuous, if not absent, during the quiescent phases of the disease. The addition of DWI sequences to conventional MRI seems to be a valid method for accurately diagnosing PML and establishing the degree of disease progression.

ObjectivesAsymmetrically prominent veins (APVs) detected on susceptibility weighted imaging (SWI) in acute stroke patients are assumed to signify compromised cerebral perfusion. We aimed to explore the role of APVs in identifying the ischemic penumbra and predicting stroke progression in acute stroke patientsMethodsTwenty patients with a middle cerebral artery ischemic infarction presenting within 24 h of symptoms onset underwent SWI following our standard MR stroke protocol imaging sequences which included diffusion-weighted imaging (DWI). Follow-up (FUP) FLAIR images were obtained at least 5 days after the initial MRI study. The Alberta Stroke Program Early CT Score (ASPECTS) was used to determine the initial infarct size, extent of APVs and final infarct size on initial DWI, SWI, and FUP images respectively. For each patient, SWI was compared with DWI images to determine match/mismatch of their respective ASPECTS values and calculate mismatch scores, whereas acute DWI findings were compared with follow-up images to identify infarct growth (IG) and calculate infarction growth scores (IGS).ResultsIG occurred in 6/10 patients with a positive DWI-SWI mismatch and in none of the patients without a positive DWI-SWI mismatch. A positive DWI/SWI mismatch was significantly associated with IG (χ2 = 8.57, p = 0.0138, Cramer’s V = 0.65). A significant inverse correlation was found between SWI ASPECTS and IGS (rs = − 0.702, p = 0.001). DWI-SWI mismatch scores were strongly correlated with IGS. (rs = 0.788, p = 0.000)ConclusionA positive DWI-SWI mismatch is an indicator of the ischemic penumbra and a predictor of infarct expansion if left untreated.

Ischemic stroke segmentation at an acute stage is vital in assessing the severity of patients' impairment and guiding therapeutic decision-making for reperfusion. Although many deep learning studies have shown attractive performance in medical segmentation, it is difficult to use these models trained on public data with private hospitals' datasets. Here, we demonstrate an ensemble model that employs two different multimodal approaches for generalization, a more effective way to perform on external datasets. First, after we jointly train a segmentation model on diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) MR modalities, the model is inferred on the DWI images. Second, a channel-wise segmentation model is trained by concatenating the DWI and ADC images as input, and then is inferred using both MR modalities. Before training with ischemic stroke data, we utilized BraTS 2021, a public brain tumor dataset, for transfer learning. An extensive ablation study evaluates which strategy learns better representations for ischemic stroke segmentation. In our study, nnU-Net well-known for robustness is selected as our baseline model. Our proposed method is evaluated on three different datasets: the Asan Medical Center (AMC) I and II, and the 2022 Ischemic Stroke Lesion Segmentation (ISLES). Our experiments are widely validated over a large, multi-center, and multi-scanner dataset with a huge amount of 846 scans. Not only stroke lesion models can benefit from transfer learning using brain tumor data, but combining the MR modalities using different training schemes also highly improves segmentation performance. The method achieved a top-1 ranking in the ongoing ISLES'22 challenge and performed particularly well on lesion-wise metrics of interest to neuroradiologists, achieving a Dice coefficient of 78.69% and a lesion-wise F1 score of 82.46%. Also, the method was relatively robust on the AMC I (Dice, 60.35%; lesion-wise F1, 68.30%) and II (Dice; 74.12%; lesion-wise F1, 67.53%) datasets in different settings. The high segmentation accuracy of our proposed method could improve radiologists' ability to detect ischemic stroke lesions in MRI images. Our model weights and inference code are available on https://github.com/MDOpx/ISLES22-model-inference .

Objective:Because dysregulated Epstein-Barr virus (EBV)-infected B cells may induce meningeal inflammation, which contributes to cortical pathology in multiple sclerosis (MS), we investigated associations between antibody responses to EBV and development of cortical pathology in MS.Methods:We included 539 patients with MS (369 with relapsing-remitting MS, 135 with secondary progressive MS, and 35 with primary progressive MS), 66 patients with clinically isolated syndrome (CIS), 63 patients with other neurologic diseases (OND), and 178 age- and sex-matched healthy controls (HC). All participants were scanned on 3T MRI. Serum samples were analyzed for IgG antibodies against EBV viral capsid antigen (VCA) and EBV nuclear antigen-1 (EBNA-1), and their quartiles were determined on the whole study sample. Differences between the study groups were assessed using analysis of covariance adjusted for multiple comparisons.Results:More than 30% of patients with MS and CIS presented with the highest quartile of anti-EBV-VCA and -EBNA-1 status compared to ≤10% of HC (p < 0.001). The figures were 9 (14.3%) and 7 (12.3%) for patients with OND. Patients with MS with the highest quartile of anti-EBV-VCA showed significantly increased T2 lesion volume (p = 0.001), T1 lesion number (p = 0.002), and T1 lesion volume (p = 0.04) and decreased gray matter (p = 0.041) and cortical (p = 0.043) volumes compared to patients with MS with lower quartiles. No significant differences of MRI outcomes in patients with CIS, patients with OND, and HC with lower or highest quartiles of anti-EBV-VCA and -EBNA-1 were detected.Conclusions:Humoral response to anti-EBV-VCA and -EBNA-1 is associated with more advanced cortical atrophy, accumulation of chronic T1 black holes, and focal white matter lesions in patients with MS.

The aim of this study was to noninvasively evaluate changes in renal stiffness, diffusion, and oxygenation in patients with chronic, advanced stage immunoglobulin A nephropathy (IgAN) by multiparametric magnetic resonance imaging using tomoelastography, diffusion-weighted imaging (DWI), and blood oxygen level-dependent (BOLD) imaging. In this prospective study, 32 subjects (16 patients with biopsy-proven IgAN and 16 age- and sex-matched healthy controls) underwent multifrequency magnetic resonance elastography with tomoelastography postprocessing at 4 frequencies from 40 to 70 Hz to generate shear wave speed (meter per second) maps reflecting tissue stiffness. In addition, DWI and BOLD imaging were performed to determine the apparent diffusion coefficient in square millimeter per second and T2* relaxation time in milliseconds, respectively. Regions including the entire renal parenchyma of both kidneys were analyzed. Areas under the receiver operating characteristic (AUCs) curve were calculated to test diagnostic performance. Clinical parameters such as estimated glomerular filtration rate and protein-to-creatinine ratio were determined and correlated with imaging findings. Success rates of tomoelastography, DWI, and BOLD imaging regarding both kidneys were 100%, 91%, and 87%, respectively. Shear wave speed was decreased in IgAN (-21%, P < 0.0001), accompanied by lower apparent diffusion coefficient values (-12%, P = 0.004). BOLD imaging was not sensitive to IgAN (P = 0.12). Tomoelastography detected IgAN with higher diagnostic accuracy than DWI (area under the curve = 0.9 vs 0.8) and positively correlated with estimated glomerular filtration rate (r = 0.66, P = 0.006). Chronic, advanced stage IgAN is associated with renal softening and restricted water diffusion. Tomoelastography is superior to DWI and BOLD imaging in detecting IgAN.

Exploring multi-b-value diffusion-weighted imaging for more accurate prostate segmentation and uncertainty estimation

BackgroundSeveral recent reports have demonstrated that the preoperative sensitivity and accuracy of identifying and locating non-palpable testes increases with the use of conventional MRI, in addition to diffusion-weighted imaging (DWI). Therefore, pre-operative prediction of the presence and location of testes using imaging techniques may guide management of intra-abdominal testis. Fowler-Stephens orchiopexy is effective for treating patients with intra-abdominal testis; however, long-term testicular function after this procedure has not been clarified. We present a case of a high intra-abdominal testis located below the kidney, and discuss the usefulness of fusion view with T2-weighted and DWI images to make a diagnosis of high intra-abdominal testis and the pathological findings to predict future fertility potential.Case presentationA 10-month-old boy was referred to the urology department for the management of non-palpable testis. We employed not only conventional MRI, but also DWI, to improve the diagnostic accuracy of non-palpable testes by MRI examination. The high-intensity mass-like structure below the kidney on the T2-weighted image and the markedly high signal intensity mass on the DWI image completely matched, which suggested that the mass below the kidney was the right testis. The patient underwent diagnostic and therapeutic laparoscopy. A testis was found under the ascending colon, 1 cm below the right kidney. We performed 2-stage Fowler-Stephens orchiopexy. The testis could be delivered to the scrotum without any tension. We examined expression patterns of the stem cell marker, undifferentiated embryonic cell transcription factor 1 (UTF1) in the testicular biopsy sample, and demonstrated that the UTF1-positive Ad spermatogonia / negative Ad spermatogonia ratio was lower in this patient than in boys his age with descended and inguinal undescended testes, indicating that spermatogonial stem cell activity may decrease remarkably in this boy.ConclusionsFusion view with T2-weighted and DWI images may be a useful diagnostic modality for high intra-abdominal testes. Fowler-Stephens orchiopexy may provide blood supply to the testis but that might not be enough to achieve spermatogenesis.

Objective: Consider Progressive Multifocal Leucoencephalopathy- Immune Reconstitution Inflammatory Syndrome (PML-IRIS) with worsening neurological symptoms and improved Cluster of Differentiation 4 (CD4) count and viral load. Background PML is a severe demyelinating disease of Central Nervous System, caused by the JC Polyomavirus. IRIS describes paradoxical worsening of pre existing infectious processes following initiation of Highly Active Anti Retroviral Therapy (HAART) and improvement in immunologic function. Design/Methods: Case Report from a Tertiary Medical Centre. Results: 41 year old man with Human Immunodeficiency Virus (HIV, non compliant with medications) presented with Right hand weakness. CD4 count was 53, Viral load was high, MRI Brain showed lesion in Left precentral gyrus, bright on Diffusion Weighted Imaging and moderate intensity on Apparent Diffusion Coefficient. He was thought to have subacute infarct, started on Aspirin, anticholesterol agent and HAART. Patient returned 6 weeks later with Right arm plegia, CD4 count had improved to 60 and viral load was undetectable. MRI Brain showed increased signal Left frontoparietal region with mild enhancement, no mass effect. Lumbar Puncture (LP) had normal cells, chemistry, and a viral PCR panel including JCV was negative. Patient was continued on HAART and sent home. He returned 3 weeks later with Right sided hemiplegia and aphasia. MRI Brain showed worsening mass effect, cavitation in the lesion with patchy nodular enhancement. Repeat CSF was normal including cytology and viral PCR. Brain biopsy showed inflammatory reactive infiltrate with abundant lipid laden macrophages, perivascular lymphocytes and rare cells reactive with JCV. A third CSF sample also revealed JCV detected at lower limit of quantitation. The patient was continued on HAART and Intra Venous (IV) Steroids started. His symptoms progressively improved. Conclusions: Increase in CD4 count and improved viral load can mount IRIS response in PML patients and IV Steroid therapy should be instituted without delay. Disclosure: Dr. Kannaditharayil has nothing to disclose.