FastMRI Prostate: A public, biparametric MRI dataset to advance machine learning for prostate cancer imaging.

Magnetic resonance imaging (MRI) has experienced remarkable advancements in the integration of artificial intelligence (AI) for image acquisition and reconstruction. The availability of raw k-space data is crucial for training AI models in such tasks, but public MRI datasets are mostly restricted to DICOM images only. To address this limitation, the fastMRI initiative released brain and knee k-space datasets, which have since seen vigorous use. In May 2023, fastMRI was expanded to include biparametric (T2- and diffusion-weighted) prostate MRI data from a clinical population. Biparametric MRI plays a vital role in the diagnosis and management of prostate cancer. Advances in imaging methods, such as reconstructing under-sampled data from accelerated acquisitions, can improve cost-effectiveness and accessibility of prostate MRI. Raw k-space data, reconstructed images and slice, volume and exam level annotations for likelihood of prostate cancer are provided in this dataset for 47468 slices corresponding to 1560 volumes from 312 patients. This dataset facilitates AI and algorithm development for prostate image reconstruction, with the ultimate goal of enhancing prostate cancer diagnosis.

FastMRI Prostate: A Publicly Available, Biparametric MRI Dataset to Advance Machine Learning for Prostate Cancer Imaging.

The fastMRI brain and knee dataset has enabled significant advances in exploring reconstruction methods for improving speed and image quality for Magnetic Resonance Imaging (MRI) via novel, clinically relevant reconstruction approaches. In this study, we describe the April 2023 expansion of the fastMRI dataset to include biparametric prostate MRI data acquired on a clinical population. The dataset consists of raw k-space and reconstructed images for T2-weighted and diffusion-weighted sequences along with slice-level labels that indicate the presence and grade of prostate cancer. As has been the case with fastMRI, increasing accessibility to raw prostate MRI data will further facilitate research in MR image reconstruction and evaluation with the larger goal of improving the utility of MRI for prostate cancer detection and evaluation. The dataset is available at https://fastmri.med.nyu.edu.

Effect of intravoxel incoherent motion on diffusion parameters in normal brain.

At very low diffusion weighting the diffusion MRI signal is affected by intravoxel incoherent motion (IVIM) caused by dephasing of magnetization due to incoherent blood flow in capillaries or other sources of microcirculation. While IVIM measurements at low diffusion weightings have been frequently used to investigate perfusion in the body as well as in malignant tissue, the effect and origin of IVIM in normal brain tissue is not completely established. We investigated the IVIM effect on the brain diffusion MRI signal in a cohort of 137 radiologically-normal patients (62 male; mean age = 50.2 ±â€¯17.8, range = 18 to 94). We compared the diffusion tensor parameters estimated from a mono-exponential fit at b = 0 and 1000 s/mm2 versus at b = 250 and 1000 s/mm2. The asymptotic fitting method allowed for quantitative assessment of the IVIM signal fraction f* in specific brain tissue and regions. Our results show a mean (median) percent difference in the mean diffusivity of about 4.5 (4.9)% in white matter (WM), about 7.8 (8.7)% in cortical gray matter (GM), and 4.3 (4.2)% in thalamus. Corresponding perfusion fraction f* was estimated to be 0.033 (0.032) in WM, 0.066 (0.065) in cortical GM, and 0.033 (0.030) in the thalamus. The effect of f* with respect to age was found to be significant in cortical GM (Pearson correlation ρ â€‹= â€‹0.35, p â€‹= â€‹3*10-5) and the thalamus (Pearson correlation ρ = 0.20, p = 0.022) with an average increase in f* of 5.17*10-4/year and 3.61*10-4/year, respectively. Significant correlations between f* and age were not observed for WM, and corollary analysis revealed no effect of gender on f*. Possible origins of the IVIM effect in normal brain tissue are discussed.

State of the Art: Machine Learning Applications in Glioma Imaging.

OBJECTIVE: Machine learning has recently gained considerable attention because of promising results for a wide range of radiology applications. Here we review recent work using machine learning in brain tumor imaging, specifically segmentation and MRI radiomics of gliomas. CONCLUSION: We discuss available resources, state-of-the-art segmentation methods, and machine learning radiomics for glioma. We highlight the challenges of these techniques as well as the future potential in clinical diagnostics, prognostics, and decision making.

Tumoral Presentation of Homonymous Hemianopia and Prosopagnosia in Cerebral Amyloid Angiopathy-Related Inflammation.

While cerebral amyloid angiopathy is a common cause of lobar hemorrhage, rarely it may be associated with an inflammatory response, thought to be incited by amyloid deposits. We report a 73-year-old woman with an extensive cancer history who presented with tumor-like lesions and symptoms of homonymous hemianopia and prosopagnosia. Found to have cerebral amyloid angiopathy-related inflammation proven by brain biopsy, she was treated successfully with immunosuppression.

Fungal Sinusitis.

Fungal sinusitis is characterized into invasive and noninvasive forms. The invasive variety is further classified into acute, chronic and granulomatous forms; and the noninvasive variety into fungus ball and allergic fungal sinusitis. Each of these different forms has a unique radiologic appearance. The clinicopathologic and corresponding radiologic spectrum and differences in treatment strategies of fungal sinusitis make it an important diagnosis for clinicians and radiologists to always consider. This is particularly true of invasive fungal sinusitis, which typically affects immuno compromised patients and is associated with significant morbidity and mortality. Early diagnosis allows initiation of appropriate treatment strategies resulting in favorable outcome.

The presence and role of iron in mild traumatic brain injury: an imaging perspective.

Mild traumatic brain injury (mTBI), although often presenting without the gross structural abnormalities seen in more severe forms of brain trauma, can nonetheless result in lingering cognitive and behavioral problems along with subtle alterations in brain structure and function. Repeated injuries are associated with brain atrophy and dementia in the form of chronic traumatic encephalopathy (CTE). The mechanisms underlying these dysfunctions are poorly understood. There is a growing body of evidence that brain iron is abnormal after TBI, and brain iron has also been implicated in a host of neurodegenerative disorders. The purpose of this article is to review evidence about the function of iron in the pathophysiology of mTBI and the role that advanced imaging modalities can play in further elucidating said function. MRI techniques sensitive to field inhomogeneities provide supporting evidence for both deep gray matter non-heme iron accumulation as well as focal microhemorrhage resulting from mTBI. In addition, there is evidence that iron may contribute to pathology after mTBI through a number of mechanisms, including generation of reactive oxygen species (ROS), exacerbation of oxidative stress from other sources, and encouragement of tau phosphorylation and the formation of neurofibrillary tangles. Finally, recent animal studies suggest that iron may serve as a therapeutic target in mitigating the effects of mTBI. However, research on the presence and role of iron in mTBI and CTE is still relatively sparse, and further work is necessary to elucidate issues such as the sources of increased iron and the chain of secondary injury.

Pencil-thin ependymal enhancement in neuromyelitis optica spectrum disorders.

AQP4 water channels are thought to be the target of autoimmune attack in neuromyelitis optica-spectrum disorders (NMOsd). AQP4 are highly expressed on ventricular ependyma. The objective of this study was to describe a novel pattern of linear, 'pencil-thin' enhancement of ventricular ependyma in NMOsd. We report two NMOsd patients with pencil-thin ependymal enhancement along the frontal and occipital horns of lateral ventricles. Differential diagnosis of ependymal enhancement should include NMOsd alongside with infectious and neoplastic etiologies. Pencil-thin ependymal enhancement may be a helpful radiological marker of NMOsd that can be used to differentiate this condition from multiple sclerosis.

Differentiating neoplastic from nonneoplastic processes in the anterior extradural space.

PURPOSE: To compare neoplastic and nonneoplastic disease in the anterior extradural space (AES) with regard to the contour of the disease and the tethering of the central septum, as seen on axial magnetic resonance (MR) images. MATERIALS AND METHODS: In this institutional review board-approved HIPAA-compliant study, the data of patients who had AES disease determined at MR imaging and underwent diagnostic biopsy were studied. Two blinded observers reviewed the MR images and assigned the patients to one of two groups on the basis of the contour of AES disease: those with a centrally convex disease contour posteriorly and those whose disease contour was tethered in the midline to the posterior aspect of the vertebral body. Biopsy results served as the standard of reference. The two-tailed Fisher exact test, the Breslow-Day test, and κ statistics were used to compare groups. The sensitivity, specificity, and accuracy of the midline tethered contour of AES disease for the detection of neoplasm were calculated. RESULTS: The data of 32 patients (16 men, 16 women; mean age, 68 years) were studied. Seventeen patients had malignant epidural disease. Fifteen patients had nonneoplastic epidural disease: Six patients had hematomas, and nine had abscesses. A greater proportion of AES neoplasms (13 [76%] and 14 [82%] of 17 lesions for observers 1 and 2, respectively) than nonneoplastic AES lesions (four [27%] and three [20%] of 15 lesions for observers 1 and 2, respectively) demonstrated midline tethering of the central septum. For observers 1 and 2, a unilobed or bilobed appearance of AES disease had sensitivities of 76% (13 of 17 lesions) and 82% (14 of 17 lesions), respectively; specificities of 73% (11 of 15 lesions) and 80% (12 of 15 lesions), respectively; and accuracies of 75% (24 of 32 lesions) and 81% (26 of 32 lesions), respectively, for the detection of neoplasm. The mean κ value for interobserver variability was 0.62 (95% confidence interval: 0.35, 0.90). CONCLUSION: AES disease preserving the midline tethering of the central septum is more common with neoplastic disease than with infections or hematomas.

Dynamic perfusion MRI characteristics of dural metastases and meningiomas: a pilot study characterizing the first-pass wash-in phase beyond relative cerebral blood volume.

OBJECTIVE: Dural metastases and meningiomas are extraaxial lesions that may be difficult to distinguish using conventional imaging methods. This distinction, however, is clinically important. Perfusion MRI may play a role in preoperative assessment. The aim of this study was to evaluate the utility of perfusion parameters in differentiating between these two entities. In particular, we evaluated two new metrics that reflect the first-pass wash-in characteristics of perfusion. MATERIALS AND METHODS: Patients with intracranial extraaxial masses who underwent perfusion MRI were included. Region-of-interest analysis was performed and several perfusion metrics were calculated including relative cerebral blood volume (rCBV), mean transit time and time to peak (TTP) enhancement from initial bolus enhancement (T0), calculated as TTP-T(0). Two new metrics characterizing first pass wash-in enhancement were also measured: relative wash-in time and wash-in slope. Lesions were divided into two groups: meningioma and metastasis. Comparisons between the two groups were made using Wilcoxon rank sum and Fisher exact tests. RESULTS: Twenty lesions were studied (12 meningioma and 8 metastases). Compared with meningiomas, relative wash-in time was statistically lower in metastases (p < 0.05). No other statistically significant differences were observed. Specifically, there was no difference between the two study groups in rCBV. CONCLUSION: First-pass wash-in characteristics of dural lesions may be useful for evaluating and characterizing lesions. In particular, a metric describing the wash-in phase of perfusion-that is, relative wash-in time-was found to be lower in metastases compared with meningiomas. Contrary to a prior report, we found rCBV to be limited in the evaluation of extraaxial lesions.

Use of diffusion-weighted imaging in recurrent central nervous system Whipple's disease: a case report and review of the literature.

A case of Whipple's disease with development of antibiotic resistance is reported. The patient's symptomatology correlated with evolution of diffusion abnormality rather than with lesion enhancement. The lesion demonstrated no hyperperfusion, moderately elevated choline, and decreased N-acetylaspartate. Conventional magnetic resonance (MR) imaging findings of central nervous system Whipple's disease are nonspecific and may mimic neoplasm. MR perfusion and spectroscopy findings are reported, which may assist in diagnosis. Change in diffusion restriction appears to be a potential imaging indicator of clinical progression and response to therapy.

Brainstem corticospinal tract diffusion tensor imaging in patients with primary posterior fossa neoplasms stratified by tumor type: a study of association with motor weakness and outcome.

OBJECTIVE: Diffusion tensor imaging (DTI) allows in vivo delineation of brainstem white matter tracts. The purpose of this study was to determine whether or not abnormalities of DTI metrics and fiber tractography correlate with neurological deficits and clinical status in patients with primary posterior fossa tumors. METHODS: A review of patients with primary posterior fossa tumors who underwent magnetic resonance imaging with DTI was performed. Patients were stratified by tumor type (well-circumscribed or infiltrating lesions). Fractional anisotropy (FA) color maps were used to localize the corticospinal tracts within the brainstem. FA, mean diffusivity, and eigenvalues were measured. Tractography was performed. Correlations between DTI metrics and clinical status and between DTI metrics and neurological examination findings were assessed within each patient group using Bonferroni correction for multiple comparisons. Comparisons of DTI metrics were also made between patient groups (infiltrating lesions versus well-circumscribed lesions). RESULTS: Thirty patients were studied (mean age, 14.1 yr; 16 male, 14 female). Eighteen patients had infiltrating lesions and 12 had well-circumscribed lesions. Twelve patients (four well-circumscribed and eight infiltrating) demonstrated motor weakness on physical examination (four right, three left, five bilateral). Patients with well-circumscribed lesions and weakness had higher mean diffusivity and lower FA in the contralateral corticospinal tract (P < 0.05). No such association was seen in patients with infiltrating tumors. In 102 total patient-years of follow-up (average follow-up period, 4.2 yr), 17 patients (six well-circumscribed and 11 infiltrating lesions) demonstrated complete response or stable disease and six patients (three well-circumscribed and three infiltrating lesions) demonstrated progressive disease or death. No differences were seen in terms of DTI metrics between patients with infiltrating lesions and those with well-circumscribed lesions. Patients with well-circumscribed tumors and a bad outcome had significantly lower transverse eigenvalue measures in the corticospinal tracts compared with those with a more favorable clinical status (P < 0.05). CONCLUSION: In patients with well-circumscribed primary posterior fossa masses, higher mean diffusivity and lower FA in the brainstem corticospinal tract are associated with contralateral motor deficits; lower transverse eigenvalue may be observed with an unfavorable clinical outcome.

The neuroradiological findings in a case of Revesz syndrome.

Revesz syndrome is a variant of dyskeratosis congenita characterized by aplastic anemia, retinopathy, and central nervous system abnormalities. We describe a 3-year-old boy in whom the spectrum of neuroimaging findings, including intracranial calcifications, cerebellar hypoplasia and unusual brain lesions were found by biopsy to be gliosis despite their enhancement and progression. In patients with dyskeratosis-related syndromes, non-neoplastic parenchymal brain lesions occur and gliosis should be considered in the differential diagnosis for progressive enhancing brain lesions. Should this finding be confirmed consistently in additional cases, brain biopsy could potentially be avoided.

Perfusion and diffusion tensor imaging in a patient with locked-in syndrome after neurosurgical vascular bypass and endovascular embolization of a basilar artery aneurysm: case report.

OBJECTIVE AND IMPORTANCE: Locked-in syndrome is a state of preserved consciousness in the setting of quadriplegia, anarthria, and usually also includes lateral gaze palsy. It is most commonly associated with upper brainstem infarction variably sparing the third cranial nerve nucleus. There are likely many etiologies that contribute to this clinical syndrome. These are incompletely understood, and the syndrome remains a rare but devastating complication that can occur after neurosurgical and neurovascular interventions. Advanced magnetic resonance imaging techniques such as perfusion and diffusion tensor imaging may help to elucidate the mechanism behind locked-in syndrome. To the authors' knowledge, there are no reports in the literature of perfusion and diffusion tensor findings in patients with this syndrome. A postprocedural case of locked-in syndrome is described with abnormalities on perfusion and diffusion tensor imaging in the absence of any changes in conventional magnetic resonance imaging. CLINICAL PRESENTATION: A 57-year-old man who presented with acute onset headache, ataxia, and other nonspecific symptoms was found on imaging to have a giant fusiform basilar artery aneurysm. INTERVENTION: A saphenous vein graft bypass between the proximal right external carotid artery and P2 segment of the right posterior cerebral artery followed immediately by endovascular embolization of the aneurysm sac and distal left vertebral artery was performed. CONCLUSION: Postprocedural angiography demonstrated patency of the bypass graft, and diffusion weighted imaging showed no evidence for acute brainstem infarction. Nevertheless, despite technically successful procedures and the absence of abnormalities on conventional magnetic resonance imaging, the patient developed quadriplegia and anarthria and remained in a locked-in state until he expired. Abnormalities were, however, seen on both perfusion and diffusion tensor imaging, where hypoperfusion, increased mean diffusivity, and decreased fractional anisotropy were observed in the ventral brainstem. The findings suggested a disruption of pontine white matter tracts. Advanced imaging techniques may allow us to image important microstructural changes that were previously not discernable and assist in the evaluation of patients with complex neurological sequelae such as locked-in syndrome.

Significance of missed polyps at CT colonography.

OBJECTIVE: Our purpose was to determine the clinical significance of polyps missed on CT colonography using histologic analysis and the natural history of colorectal polyps and to propose guidelines for follow-up colon surveillance based on CT colonographic findings. SUBJECTS AND METHODS. One hundred eighty-six men (age range, 40-87 years; mean, 62.3 years) underwent CT colonography immediately before conventional colonoscopy. All polyps detected on CT colonography were measured and imaged, and their segmental location was documented. All polyps detected on colonoscopy were measured, photographed, biopsied, and histologically analyzed. Results of CT colonography and conventional colonoscopy were compared with the final pathology reports. Conventional colonoscopy was used as the gold standard unless CT colonography showed a lesion measuring 10 mm or more that was not detected on conventional colonoscopy and had characteristics of a polyp. In these cases, follow-up conventional colonoscopy was offered. RESULTS: One hundred ninety-one polyps were detected on conventional colonoscopy. CT colonography prospectively detected 53 polyps. Histologic analysis of the polyps not detected on CT colonography showed that of those 5 mm or smaller, 58.1% were not adenomas, and of those measuring 6-9 mm, 42.8% were not adenomas. Both missed polyps at CT colonography of 10 mm or more were adenomas. Of the 22 polyps measuring 10 mm or more, three were not detected on conventional colonoscopy. Of these three, CT colonography showed a lesion having characteristics of a polyp, follow-up endoscopy confirmed the presence of the lesion, and histologic analysis showed a villous adenoma, a tubulovillous adenoma, and a tubular adenoma. CONCLUSION: If CT colonography shows no abnormality, follow-up screening in 5 years is recommended. If CT colonography detects a lesion smaller than 5 mm, follow-up imaging in 3-5 years is recommended. If CT colonography detects a lesion measuring 6 mm or more, endoscopy and polypectomy should be offered unless contraindicated.

Colorectal polyps and cancers in asymptomatic average-risk patients: evaluation with CT colonography.

PURPOSE: To compare thin-section multi-detector row computed tomographic (CT) colonography with conventional colonoscopy in the evaluation of colorectal polyps and cancer in asymptomatic average-risk patients. MATERIALS AND METHODS: Sixty-eight asymptomatic men (age > 50 years) scheduled to undergo screening colonoscopy were enrolled in this study. CT colonography was followed by conventional colonoscopy, performed on the same day. Supine and prone CT colonography were performed after colonic insufflation with room air. A gastroenterologist measured all polyps, which were categorized as 1-5, 6-9, or over 10 mm. Biopsy and histologic evaluation were performed of all polyps. CT colonography and colonoscopy results were compared for location, size, and morphology of detected lesions. Point estimates and 95% CIs were provided for specificity and sensitivity of CT by using results at conventional colonoscopy as the reference standard. RESULTS: At colonoscopy, 98 polyps were identified in 39 patients; 21 (21.4%) of 98 were detected at CT colonography. Sensitivity was 11.5% (nine of 78) for polyps 1-5 mm, 52.9% (nine of 17) for polyps 6-9 mm, and 100% (three of three) for polyps over 10 mm. Results at colonoscopy were normal in 29 (42.6%) of 68 patients; at CT colonography, results were correctly identified as normal in 26 of these 29 patients. In one of these patients, a lesion larger than 10 mm was detected at CT colonography. The per-patient specificity of CT was 89.7% (26 of 29; 95% CI: 72.7%, 97.8%). The mean time for CT image interpretation was 9 minutes. CONCLUSION: In patients at average risk for colorectal cancer, CT colonography is a sensitive and specific screening test for detecting polyps 10 mm or larger; the sensitivity for detecting smaller polyps is decreased. Examination findings can be interpreted in a clinically feasible amount of time.

CT colonography data interpretation: effect of different section thicknesses--preliminary observations.

PURPOSE: To evaluate if differences exist in the interpretation of thin- and thick-section reconstructions at computed tomographic (CT) colonography. MATERIALS AND METHODS: Twenty-five patients underwent multi-detector row CT colonography prior to colonoscopy. CT images were reconstructed with two methods: 1.25-mm sections reconstructed every 1 mm (thin) and 5-mm sections reconstructed every 2 mm (thick). Two independent readers interpreted thin sections, then waited a minimum of 15 days before interpreting thick sections. With colonoscopy as the reference standard, comparisons were made between interpretation of thin and thick sections, including sensitivity, specificity, and number of false-positive observations. Interpretation times were recorded, and comparisons were made by using repeated measures analysis of variance. For all tests, P <.05 indicated a statistically significant difference. RESULTS: At colonoscopy, 10 patients had 12 polyps (< or =5 mm, n = 7; 6-9 mm, n = 2; > or =10 mm, n = 3). Sensitivity for polyp detection was statistically indistinguishable for thin and thick sections. Reader 1 had three false-positive findings with thin sections and six with thick sections. Reader 2 had six false-positive findings with thin sections and 11 with thick sections. For both readers, the number of false-positive findings was significantly lower for thin sections than for thick sections (P =.035). Specificity was 93.3% with thin sections and 80.0% with thick sections for reader 1 and 80.0% with thin sections and 73.3% with thick sections for reader 2. Mean interpretation time for reader 1 was significantly longer with thin sections (P <.001). Mean interpretation time for reader 2 was 13.0 minutes for both thin and thick sections. CONCLUSION: Specificity improved for both readers with thin sections, with no difference in sensitivity.

Filling defects at CT colonography: pseudo- and diminutive lesions (the good), polyps (the bad), flat lesions, masses, and carcinomas (the ugly).

Numerous filling defects may be detected in the colon during interpretation of data sets obtained with computed tomographic (CT) colonography. A series of 230 patients were evaluated with thin-section multidetector row CT colonography immediately before conventional colonoscopy. In all cases, the interpreting radiologist and gastroenterologist reviewed the imaging findings as well as the results of histologic analysis of biopsy specimens to determine the causes of filling defects. In many cases, the cause of a filling defect can be confidently determined at CT colonography by using combinations of two- and three-dimensional images. However, lesions will occasionally be indeterminate because of overlapping features and will require further evaluation with endoscopy. With knowledge of the morphologic and attenuation characteristics of the various filling defects in the colon, one should be able to differentiate those filling defects detected at CT colonography that require no further evaluation from those that require endoscopic interrogation.