Restricted diffusion in benign intracranial neoplasms: a narrative review.

Diffusion-weighted imaging (DWI) is a valuable diagnostic tool, which provides functional information by exploring the free diffusivity of water molecules into intra- and inter-cellular spaces that in tumours mainly depend on cellularity. It provides information regarding the tumour grade and helps with the diagnosis. Often high-grade tumours show restricted diffusion due to a high degree of cellularity, increased nuclear-to-cytoplasmic ratio, and reduced extracellular space. Benign central nervous system (CNS) tumours rarely show restricted diffusion on magnetic resonance imaging (MRI), and most of them have a characteristic imaging appearance. When benign CNS neoplasms reveal restricted diffusion on MRI, the radiologist is compelled to suggest a malignant neoplasm, making their diagnosis challenging. Knowledge of these exceptions helps to avoid possible errors in diagnosis. We present this integrated review with clinical, radiology-pathological correlation.

Clinically Relevant Myocardium Segmentation in Cardiac Magnetic Resonance Images.

Deep learning approaches have shown great success in myocardium region segmentation in Cardiac MR (CMR) images. However, most of these often ignore irregularities such as protrusions, breaks in contour, etc. As a result, the common practice by clinicians is to manually correct the obtained outputs for the evaluation of myocardium condition. This paper aims to make the deep learning systems capable of handling the aforementioned irregularities and satisfy desired clinical constraints, necessary for various downstream clinical analysis. We propose a refinement model which imposes structural constraints on the outputs of the existing deep learning-based myocardium segmentation methods. The complete system is a pipeline of deep neural networks where an initial network performs myocardium segmentation as accurate as possible and the refinement network removes defects from the initial output to make it suitable for clinical decision support systems. We experiment with datasets collected from four different sources and observe consistent final segmentation outputs with improvement up to 8% in Dice Coefficient and up to 18 pixels in Hausdorff Distance due to the proposed refinement model. The proposed refinement strategy leads to qualitative and quantitative improvements in the performances of all the considered segmentation networks. Our work is an important step towards the development of a fully automatic myocardium segmentation system. It can also be generalized for other tasks where the object of interest has regular structure and the defects can be modelled statistically.

Suboptimal Chest Radiography and Artificial Intelligence: The Problem and the Solution.

Chest radiographs (CXR) are the most performed imaging tests and rank high among the radiographic exams with suboptimal quality and high rejection rates. Suboptimal CXRs can cause delays in patient care and pitfalls in radiographic interpretation, given their ubiquitous use in the diagnosis and management of acute and chronic ailments. Suboptimal CXRs can also compound and lead to high inter-radiologist variations in CXR interpretation. While advances in radiography with transitions to computerized and digital radiography have reduced the prevalence of suboptimal exams, the problem persists. Advances in machine learning and artificial intelligence (AI), particularly in the radiographic acquisition, triage, and interpretation of CXRs, could offer a plausible solution for suboptimal CXRs. We review the literature on suboptimal CXRs and the potential use of AI to help reduce the prevalence of suboptimal CXRs.

Congenital Anomalies of Aortic Arch: A Pictorial Essay.

Aortic abnormalities account for 15 to 20% of all congenital cardiovascular diseases. The purpose of this pictorial essay is to illustrate various congenital anomalies of the aortic arch, which influence patient management and outcome.

Cardiovascular magnetic resonance characterization of rheumatic mitral stenosis: findings from three worldwide endemic zones.

BACKGROUND: Cardiac remodeling in rheumatic mitral stenosis (MS) is complex and incompletely understood. The objective of this study was to evaluate cardiac structural and functional changes in a cohort of patients with rheumatic MS using cardiovascular magnetic resonance (CMR). METHODS: This retrospective study included 40 patients with rheumatic MS, consisting of 19 patients from India, 15 patients from China, and 6 patients from Mexico (median (interquartile range (IQR)) age: 45 years (34-55); 75% women). Twenty patients were included in the control group. CMR variables pertaining to morphology and function were collected. Late gadolinium enhancement (LGE) sequences were acquired for tissue characterization. Statistical analyses were performed using the Kruskal-Wallis test and the chi-square test. RESULTS: Compared to the control group, patients with MS had lower left ventricular (LV) ejection fraction (51% (42%-55%) vs 60% (57%-65%), p < 0.001), lower right ventricular (RV) ejection fraction (44% (40%-52%) vs 64% (59%-67%), p < 0.001), higher RV end-diastolic volume (72 (58-87) mL/m2 vs 59 (49-69) mL/m2, p = 0.003), larger left atrial volume (87 (67-108) mL/m2 vs 29 (22-34) mL/m2, p < 0.001), and right atrial areas (20 (16-23) cm2 vs 13 (12-16) cm2, p < 0.001). LGE was prevalent in patients with rheumatic MS (82%), and was commonly located at the RV insertion sites. Furthermore, the patient cohorts from India, China, and Mexico were heterogeneous in terms of baseline characteristics and cardiac remodeling. CONCLUSION: Our findings demonstrated that biventricular dysfunction, right and left atrial remodeling, and LGE at the RV insertion sites are underappreciated in contemporary rheumatic MS. Further studies are needed to elucidate the prognostic implications of these findings.

Utility of DTI (Diffusion Tensor Imaging) Metrics to Study Microstructural Changes of Trigeminal Nerve in Patients with Trigeminal Neuralgia (TN).

Aims: To study the trigeminal nerve tractography and assessment of diffusion tensor imaging (DTI) parameters by comparing the values of fractional anisotropy (FA) of trigeminal (V) nerve on the affected side with that of the unaffected opposite side. Materials and Methods: Prospective comparative study done for one year included 30 patients who presented with trigeminal neuralgia and 30 controls who did not have any present or past history of neurological or neurosurgical symptoms were enrolled in the study. Results: Most common age of presentation of TN is >50 years, and the commonly involved branch is V2 (maxillary branch of the trigeminal nerve). Most of the patients were having symptoms for more than 1 year. The superior cerebellar artery was the most common vessel compressing the V nerve at the root entry zone (REZ), followed in the order by anterior inferior cerebellar artery and petrosal vein. Neurovascular compression (NVC) was more commonly seen in the study group when compared with the control group. In all the patients in the study group, fractional anisotropy (FA) was decreased on the affected side as compared to the unaffected side. In the study group, 10 patients were having NVC on both sides, but FA was significantly decreased only on the affected side. No significant difference in FA values at the REZ of bilateral V nerves in the control group. Conclusion: DTI metrics of the trigeminal nerve is a very helpful imaging technique in patients with trigeminal neuralgia. It not only helps in anatomical imaging but also reinforces the association between NVC and TN.

Semi-Quantitative Scoring of Late Gadolinium Enhancement of the Left Ventricle in Patients with Ischemic Cardiomyopathy: Improving Interobserver Reliability and Agreement Using Consensus Guidance from the Asian Society of Cardiovascular Imaging-Practical Tutorial (ASCI-PT) 2020.

OBJECTIVE: This study aimed to evaluate the effect of implementing the consensus statement from the Asian Society of Cardiovascular Imaging-Practical Tutorial 2020 (ASCI-PT 2020) on the reliability of cardiac MR with late gadolinium enhancement (CMR-LGE) myocardial viability scoring between observers in the context of ischemic cardiomyopathy. MATERIALS AND METHODS: A total of 17 cardiovascular imaging experts from five different countries evaluated CMR obtained in 26 patients (male:female, 23:3; median age [interquartile range], 55.5 years [50-61.8]) with ischemic cardiomyopathy. For LGE scoring, based on the 17 segments, the extent of LGE in each segment was graded using a five-point scoring system ranging from 0 to 4 before and after exposure according to the consensus statement. All scoring was performed via web-based review. Scores for slices, vascular territories, and total scores were obtained as the sum of the relevant segmental scores. Interobserver reliability for segment scores was assessed using Fleiss' kappa, while the intraclass correlation coefficient (ICC) was used for slice score, vascular territory score, and total score. Inter-observer agreement was assessed using the limits of agreement from the mean (LoA). RESULTS: Interobserver reliability (Fleiss' kappa) in each segment ranged 0.242-0.662 before the consensus and increased to 0.301-0.774 after the consensus. The interobserver reliability (ICC) for each slice, each vascular territory, and total score increased after the consensus (slice, 0.728-0.805 and 0.849-0.884; vascular territory, 0.756-0.902 and 0.852-0.941; total score, 0.847 and 0.913, before and after implementing the consensus statement, respectively. Interobserver agreement in scoring also improved with the implementation of the consensus for all slices, vascular territories, and total score. The LoA for the total score narrowed from ± 10.36 points to ± 7.12 points. CONCLUSION: The interobserver reliability and agreement for CMR-LGE scoring for ischemic cardiomyopathy improved when following guidance from the ASCI-PT 2020 consensus statement.

Utility of apparent diffusion coefficient (ADC) values in differentiating benign and malignant skull lesions with histopathological (HPE) correlation.

AIM: Assess role of ADC in differentiating benign and malignant skull lesions and to evaluate the added value of ADC over conventional MRI in facilitating the differentiation. MATERIALS AND METHODS: 53 patients (24 males, 29 females; age 3-75 years) were subjected to both conventional and Diffusion weighted (DWI) MR imaging. DWI was performed using a single-shot SE EPI sequence with b-values of 0& 1000 s/mm2 on 1.5 T MR scanner. Margins of the lesion, number, soft-tissue component, local extension, periosteal reaction and enhancement pattern were the parameters used for differentiating benign & malignant lesions by conventional MRI. ADC values (mean of 3 ROIs over solid component) were calculated. Conventional MRI characteristics and ADC value of lesions were evaluated & compared using statistical analysis. These findings were compared and correlated with histopathology of the skull lesions. RESULTS: 24 malignant and 29 benign lesions were identified on HPE (Histopathological examination) in 53 patients. ADC cut-off value of 0.96 × 10-3 mm2/s obtained from ROC curve was found to have 75.47% accuracy, 87.5% sensitivity, 65.52% specificity, 67.74% PPV and 86.36% NPV for differentiating malignant from benign lesions. Statistically significant differences (p < 0.05) were seen in the mean ADC values of malignant (0.64 ± 0.42 × 10-3 mm2/s) and benign lesions (1.14 ± 0.56 × 10-3 mm2/s). The sensitivity, specificity, PPV and NPV in differentiating benign & malignant skull lesions were found to be 58.33%, 62.07%, 56% and 64.29% respectively, with diagnostic accuracy of 60.38% on using conventional MRI alone and 75%, 72.41%, 69.23% and 77.78% respectively, with diagnostic accuracy of 73.58% on using conventional MRI with ADC. CONCLUSION: ADC is a promising non-invasive parameter that facilitates differentiation between benign and malignant skull lesions. It is a robust biomarker to narrow differentials when conventional imaging features are indeterminate.

Multimodal Imaging and Visual Evoked Potentials Reveal Key Structural and Functional Features That Distinguish Symptomatic From Presymptomatic Huntington's Disease Brain.

BACKGROUND: Huntington's disease (HD) is a progressive neurodegenerative disorder characterized by motor, cognitive, and psychiatric abnormalities. Currently, matched analyses of structural and functional differences in the brain from the same study cohort and, specifically, in HD patients from an ethnically diverse Indian population are lacking. Such findings aid in identifying noninvasive and sensitive imaging biomarkers. OBJECTIVE: The aim of the study was to understand the structural and functional differences between HD and control brain, and presymptomatic and symptomatic HD brain in the Indian population. MATERIALS AND METHODS: Seventeen HD (11 symptomatic HD [S-HD] and six presymptomatic HD [P-HD], with comparable CAG repeats), and 12 healthy controls were examined. Macrostructural (volume), microstructural (diffusivity), and functional (neurochemical levels and glucose metabolism) imaging of the brain was done along with the determination of visual latencies. RESULTS: HD brain showed increased intercaudate distance; significant subcortical volumetric loss; reduced fractional anisotropy; increased mean, axial, and radial diffusivity; lower levels of total N-acetyl aspartate; elevated total choline levels; and reduced glucose metabolism compared with control brain. Interestingly, compared with P-HD, S-HD patients demonstrated a strong inverse correlation between age at onset and CAG repeat length, and prolonged P100 latency. In addition, caudate and putamen in S-HD brain showed significant volumetric loss and increased diffusivity compared with P-HD brain. CONCLUSIONS: HD brain showed distinct macrostructural, microstructural, and functional differences compared with control brain in the Indian population. Interestingly, patients with S-HD had a significant volumetric loss, increased diffusivity, altered neurochemical profile, and delayed P100 latency compared with P-HD patients. Examining these alterations clinically could aid in monitoring the progression of HD.

Computed tomography features of cor triatriatum: an institutional review.

OBJECTIVES: Cor Triatriatum is a rare anomaly that can either involves the left atrium (Cor Triatriatum Sinister-CTS) or the right atrium (Cor Triatriatum Dexter- CTD). Preoperative identification of this anomaly is important in determining patient treatment course. The objective of this paper is to understand imaging findings, classification and to familiarise the reader with other associated congenital cardiac anomalies that influence patient management. METHODS: From the hospital electronic health records (EHR) database, we identified 10 patients of Cor Triatriatum out of 974 patients who underwent cardiac CT between 15 July 2014 and 20 March 2020 for congenital heart disease. Medical records and imaging findings were reviewed retrospectively. RESULTS: Out of 10 patients, nine patients had CTS (90%) and only one patient had CTD (10%). Five out of nine patients (55.5%) had CTS type II and four (44.4%) had CTS type III. The mean of the membrane orifices in CTS type III was 18.5 mm and was 5.78 mm in CTS type II. Pulmonary veins were dilated in all patients of CTS type II (62.5%), two patient of CTS type III (25%) and in only patient with CTD (12.5%). Ostium secundum atrial septal defect was the most common (66%) associated cardiac anomaly, followed by ventricular septal defect (44%). CONCLUSIONS: CT allows excellent pre-operative evaluation of Cor Triatriatum and associated cardiac anomalies. ADVANCES IN KNOWLEDGE: CT is excellent in making a diagnosis and classifying Cor Triatriatum and for identification of cardiac anomalies and complications associated with it.

An Institutional Review of Tuberculosis Spine Mimics on MR Imaging: Cases of Mistaken Identity.

Although MRI has a spectrum of findings which help in the diagnosis of tuberculosis (TB) spine, a broad spectrum of spine pathologies resemble Pott's spine on MRI and are often missed due to inadequate clinical details. As a result, patients are often subject to unnecessary biopsy. A blinded radiologist may misdiagnose such mimic cases as TB. Our aim is to enable the reader to learn the main criteria that differentiate spine TB from other spine etiologies that mimic TB. A retrospective search was done and authors collected only MRI spine reports that showed a differential diagnosis or diagnosis of TB spine from the computer-based data records of the institution over a four-year period. This revealed 306 cases of TB spine out of which 78 cases with an alternate diagnosis that resembled TB spine were included. We describe a single institute review of 78 such cases that resemble and mimic Pott's spine on MRI. The cases being: (n = 15) pyogenic spondylitis, (n = 1) brucellar spondylodiscitis, (n = 12) rheumatoid arthritis, (n = 12) metastases, (n = 8) lymphoma, (n = 5) post-trauma fractures, (n = 10) degenerative disc disease, (n = 2) Baastrup's disease, (n = 9) osteoporotic fracture, (n = 3) spinal neuropathic arthritis, and (n = 1) case of Rosai-Dorfman disease. The clinical and radiological findings of all these cases were correlated with lab findings and histopathology wherever necessary. Appropriate recognition of these entities that resemble and mimic TB spine on MRI is important for optimal patient care. This paper exposes radiologists to a variety of spine pathologies for which biopsy is not indicated, and highlights key imaging findings of these entities to facilitate greater diagnostic accuracy in clinical practice.

Myriad of MR imaging phenotypes of primary central nervous system lymphoma in a cohort of immunocompetent Indian patient population.

PCNSL (primary central nervous system lymphoma) is a chemosensitive and radiosensitive tumor, and early diagnosis has a significant impact on management. Unlike many other brain tumors, radical surgical excision of PCNSLs is not indicated because these lesions are highly infiltrative and even partial resection leads to a bad prognosis. The goal of this study is to highlight the unusual radiological presentation of PCNSLs and increase the awareness, familiarity, and global database of our observations that pose a challenge on management.

Gossypiboma of Axilla: Imaging Pitfalls on Fluorodeoxyglucose Positron Emission Tomography and Computed Tomography.

18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) with computed tomography (CT) has become the standard of care in staging, restaging, and response assessment of various malignancies including malignant melanoma. However, nonspecific uptake of FDG can occur in infectious and inflammatory conditions and can mimic a tumor. We present here a case of gossypiboma of the axillary region with FDG uptake detected in a patient with malignant melanoma of the upper extremity and discuss the potential pitfalls of this entity on FDG-PET/CT.

Could knee inflammatory synovitis be induced by pembrolizumab?

Pembrolizumab, a selective anti-PD-1 humanized monoclonal antibody, reactivates T cells to fight cancer. Immune-related adverse events such as autoimmune colitis, pneumonitis, hepatitis, nephritis, hypophysitis, and thyroiditis may occur during, or weeks to months after therapy. Pemprolizumab-induced synovitis is rarely reported. With the wide use of immunotherapy to treat cancers, physicians need to be aware of this rare immune-related adverse event and provide immediate treatment to avoid permanent joint damage.

Complications exclusive to long strut grafts used following multilevel cervical corpectomy: Utilization of advanced imaging techniques.

When surgical decompression of cervical spine is considered, multilevel cervical corpectomy with long strut grafts is the preferred treatment. This procedure is used in a variety of pathologies including degenerative disease, tumors, trauma and infection. Corpectomy with interbody grafting helps in adequate spinal canal and neural decompression compared to multilevel discectomy, which could be difficult as well as inadequate. Fibular/iliac strut grafts are used for reconstruction along with a stabilizing hardware in this procedure. So far, complete imaging spectrum of complications exclusive to strut graft has not been reported in the literature. This pictorial essay presents complications exclusive to the strut graft, utility of advanced imaging in diagnosis and a brief note on the clinical management of complications.

Tree-in-bud Appearance in the Brain: Fungal Granuloma on Contrast Magnetic Resonance Imaging.

We describe a case of dural-based homogenously enhancing fungal granuloma in a 29-year-old male who presented with 3 months history of headache. The peculiarity of the case was that there were streaky areas of enhancement around the lesion in the brain parenchyma which resembled tree-in-bud like appearance. The patient underwent surgery and histopathological analysis revealed numerous Aspergillus hyphae. To the best of our knowledge, this is the first case report of a fungal granuloma with atypical parenchymal enhancement pattern.

Susceptibility weighted magnetic resonance imaging of brain: A multifaceted powerful sequence that adds to understanding of acute stroke.

CONTEXT: To evaluate the additional information that susceptibility weighted sequences and datasets would provide in acute stroke. AIMS: The aim of this study were to assess the value addition of susceptibility weighted magnetic resonance imaging (SWI) of brain in patients with acute arterial infarct. MATERIALS AND METHODS: All patients referred for a complete brain magnetic resonance imaging (MRI) between March 2010 and March 2011 at our institution had SWI as part of routine MRI (T1, T2, and diffusion imaging). Retrospective study of 62 consecutive patients with acute arterial infarct was evaluated for the presence of macroscopic hemorrhage, petechial micro-bleeds, dark middle cerebral artery (MCA) sign and prominent vessels in the vicinity of infarct. RESULTS: SWI was found to detect hemorrhage not seen on other routine MRI sequences in 22 patients. Out of 62 patients, 17 (10 petechial) had hemorrhage less than 50% and 5 patients had greater than 50% area of hemorrhage. A "dark artery sign" due to thrombus within the artery was seen in 8 out of 62 patients. Prominent cortical and intraparenchymal veins were seen in 14 out of 62 patients. CONCLUSIONS: SWI has been previously shown to be sensitive in detecting hemorrhage; however is not routinely used in stroke evaluation. Our study shows that SWI, by virtue of identifying unsuspected hemorrhage, central occluded vessel, and venous congestion is additive in value to the routine MR exam and should be part of a routine MR brain in patients suspected of having an acute infarct.

Utility of the inversion scout sequence (TI scout) in diagnosing myocardial amyloid infiltration.

To evaluate the utility of inversion scout (TI-scout) obtained during cardiac magnetic resonance imaging (CMR) in diagnosing myocardial amyloid infiltration. A retrospective analysis of CMR exams in 39 patients (24 males, age range 29-77 years) was performed. Imaging was performed on a 1.5T system, and included steady state cine, post contrast TI-scout and delayed enhancement images. Evaluations included studies in 13 patients with myocardial amyloidosis and 26 patients without myocardial amyloidosis. To characterize abnormal nulling, the time to myocardial nulling on the TI scout was compared to the null times of the blood pool and spleen for each scan. The sensitivity and specificity of different tissue nulling abnormalities for myocardial amyloidosis were computed. The null times of tissues in 18/26 (69%) patients in the non-amyloid group followed a consistent order with the blood pool null time preceding the myocardial nulling which was equal to that of splenic nulling (Type 1 pattern). This order differed in all 13 patients with myocardial amyloidosis described as three non-mutually exclusive nulling categories: 10 patients had myocardial null time preceding or coincident with blood pool (Type 2 pattern); in 11 patients myocardial null time was non-coincident with splenic nulling (Type 3 pattern); and in 8 patients myocardial null time was non-coincident with both blood pool AND splenic nulling (Type 4 pattern). While no patient exhibited Type 4 nulling pattern in the non-amyloid group, 1/26 patient had a Type 2 and 7/26 patients had a Type 3 nulling pattern. A sensitivity of 100% was obtained when either Type 2 OR Type 3 nulling was present while a specificity of 100% was obtained when both Type 2 AND Type 3 nulling were present together (Type 4 pattern). Our study demonstrates that the pattern of nulling on the TI scout sequence CMR has potential diagnostic utility for the presence of myocardial amyloidosis. The temporal pattern of myocardial, blood pool and splenic nulling needs to be carefully evaluated on the TI scout sequence and could prove useful in other infiltrative cardiomyopathies.

Diffusion-weighted imaging: As the first diagnostic clue to Creutzfeldt Jacob disease.

We describe a case report where the diagnosis of sporadic Creutzfeldt-Jakob disease(CJD) was suspected by the magnetic resonance imaging (MRI) radiologist in a 75-year-old lady who presented with rapid cognitive decline. MRI revealed cortical T2 and FLAIR(fluid attenuation and inversion recovery) hyperintensities in bilateral fronto-parietal and temporo-occipital locations and showed significant restriction on diffusion-weighted images(DWI). In this case report, we discuss the role of MRI to suspect the diagnosis of CJD in appropriate clinical settings.