Dorsoventral splitting of the infundibulum in a child with pituitary hypoplasia.

Pituitary development arises from ectodermal tissue creating Rathke's pouch and ultimately the adenohypophysis anteriorly whereas neuroectodermal tissue arising from the diencephalon creates the neurohypophysis posteriorly. Alterations in pituitary development can lead to hormonal dysregulation and dysfunction. Following clinical suspicion of pituitary endocrinopathy, MRI plays a vital role in identifying and characterizing underlying structural abnormalities of the pituitary gland, as well as any associated extrapituitary findings. Here we report a case of an 18-month-old female presenting with short stature and growth hormone deficiency. MRI was notable for a shallow sella turcica, a hypoplastic adenohypophysis, thin pituitary stalk, and ectopic neurohypophysis. Interestingly, the pituitary stalk was noted to split dorsoventrally with a split pituitary bright spot and T1 hypointense lobe hypothesized to represent separation of the posterior pituitary lobes.

Technical note: Improved differentiation of calcification from hemosiderin using paramagnetic- and diamagnetic-specific magnetic resonance susceptibility weighted imaging (p-SWI, d-SWI).

INTRODUCTION: Differentiation of calcification and calcium-containing tissue from blood products remains challenging using magnetic resonance imaging (MRI). We developed a novel post-processing algorithm which creates both paramagnetic- and diamagnetic-specific SWI images generated from T2* weighted images using distinct "positive" and "negative" phase masks. METHODS: 10 patients who had undergone clinical MRI scanning of the brain with a rapid echo planar based T2*-weighted EPI-GRE pulse sequence with evidence for either hemosiderin and/or calcifications were retrospectively identified. Complex raw k-space data from individual imaging coils were then extracted, reconstructed, and appropriately combined to produce magnitude and phase images using a phase preserving method. The final reconstructed images included the T2* EPI-GRE magnitude images, p-SWI and d-SWI images. Filtered phase images were also available for review. Correlation with CT scans and MR imaging appearance over time corroborated the composition of the voxels. RESULTS: Differential "blooming" of diamagnetic and paramagnetic foci was readily identified on the corresponding p-SWI and d-SWI images and provided fast and reliable visual differentiation of diamagnetic from paramagnetic susceptibility effects by ascertaining which of the two images depicted the greatest "blooming" effect. Correlation with the available filtered phase maps was not necessary for differentiation of paramagnetic from diamagnetic image components. CONCLUSION: Clinical interpretation of SWI images can be further enhanced by creating specific p-SWI and d-SWI image pairs which contain greater visual information than the combination of standard p-SWI images and phase image.

Evaluation of a New, Highly Flexible Radiofrequency Coil for MR Simulation of Patients Undergoing External Beam Radiation Therapy.

PURPOSE: To evaluate the performance of a new, highly flexible radiofrequency (RF) coil system for imaging patients undergoing MR simulation. METHODS: Volumetric phantom and in vivo images were acquired with a commercially available and prototype RF coil set. Phantom evaluation was performed using a silicone-filled humanoid phantom of the head and shoulders. In vivo assessment was performed in five healthy and six patient subjects. Phantom data included T1-weighted volumetric imaging, while in vivo acquisitions included both T1- and T2-weighted volumetric imaging. Signal to noise ratio (SNR) and uniformity metrics were calculated in the phantom data, while SNR values were calculated in vivo. Statistical significance was tested by means of a non-parametric analysis of variance test. RESULTS: At a threshold of p = 0.05, differences in measured SNR distributions within the entire phantom volume were statistically different in two of the three paired coil set comparisons. Differences in per slice average SNR between the two coil sets were all statistically significant, as well as differences in per slice image uniformity. For patients, SNRs within the entire imaging volume were statistically significantly different in four of the nine comparisons and seven of the nine comparisons performed on the per slice average SNR values. For healthy subjects, SNRs within the entire imaging volume were statistically significantly different in seven of the nine comparisons and eight of the nine comparisons when per slice average SNR was tested. CONCLUSIONS: Phantom and in vivo results demonstrate that image quality obtained from the novel flexible RF coil set was similar or improved over the conventional coil system. The results also demonstrate that image quality is impacted by the specific coil configurations used for imaging and should be matched appropriately to the anatomic site imaged to ensure optimal and reproducible image quality.

Arterial Spin Labeling Applications in Pediatric and Adult Neurologic Disorders.

Arterial spin labeling (ASL) is a powerful noncontrast magnetic resonance imaging (MRI) technique that enables quantitative evaluation of brain perfusion. To optimize the clinical and research utilization of ASL, radiologists and physicists must understand the technical considerations and age-related variations in normal and disease states. We discuss advanced applications of ASL across the lifespan, with example cases from children and adults covering a wide variety of pathologies. Through literature review and illustrated clinical cases, we highlight the subtleties as well as pitfalls of ASL interpretation. First, we review basic physical principles, techniques, and artifacts. This is followed by a discussion of normal perfusion variants based on age and physiology. The three major categories of perfusion abnormalities-hypoperfusion, hyperperfusion, and mixed patterns-are covered with an emphasis on clinical interpretation and relationship to the disease process. Major etiologies of hypoperfusion include large artery, small artery, and venous disease; other vascular conditions; global hypoxic-ischemic injury; and neurodegeneration. Hyperperfusion is characteristic of vascular malformations and tumors. Mixed perfusion patterns can be seen with epilepsy, migraine, trauma, infection/inflammation, and toxic-metabolic encephalopathy. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY STAGE: 3.

Whole-brain 3D MR fingerprinting brain imaging: clinical validation and feasibility to patients with meningioma.

PURPOSE: MR fingerprinting (MRF) is a MR technique that allows assessment of tissue relaxation times. The purpose of this study is to evaluate the clinical application of this technique in patients with meningioma. MATERIALS AND METHODS: A whole-brain 3D isotropic 1mm3 acquisition under a 3.0T field strength was used to obtain MRF T1 and T2-based relaxometry values in 4:38 s. The accuracy of values was quantified by scanning a quantitative MR relaxometry phantom. In vivo evaluation was performed by applying the sequence to 20 subjects with 25 meningiomas. Regions of interest included the meningioma, caudate head, centrum semiovale, contralateral white matter and thalamus. For both phantom and subjects, mean values of both T1 and T2 estimates were obtained. Statistical significance of differences in mean values between the meningioma and other brain structures was tested using a Friedman's ANOVA test. RESULTS: MR fingerprinting phantom data demonstrated a linear relationship between measured and reference relaxometry estimates for both T1 (r2 = 0.99) and T2 (r2 = 0.97). MRF T1 relaxation times were longer in meningioma (mean ± SD 1429 ± 202 ms) compared to thalamus (mean ± SD 1054 ± 58 ms; p = 0.004), centrum semiovale (mean ± SD 825 ± 42 ms; p < 0.001) and contralateral white matter (mean ± SD 799 ± 40 ms; p < 0.001). MRF T2 relaxation times were longer for meningioma (mean ± SD 69 ± 27 ms) as compared to thalamus (mean ± SD 27 ± 3 ms; p < 0.001), caudate head (mean ± SD 39 ± 5 ms; p < 0.001) and contralateral white matter (mean ± SD 35 ± 4 ms; p < 0.001) CONCLUSIONS: Phantom measurements indicate that the proposed 3D-MRF sequence relaxometry estimations are valid and reproducible. For in vivo, entire brain coverage was obtained in clinically feasible time and allows quantitative assessment of meningioma in clinical practice.

Deep neural network to locate and segment brain tumors outperformed the expert technicians who created the training data.

Purpose: Deep learning (DL) algorithms have shown promising results for brain tumor segmentation in MRI. However, validation is required prior to routine clinical use. We report the first randomized and blinded comparison of DL and trained technician segmentations. Approach: We compiled a multi-institutional database of 741 pretreatment MRI exams. Each contained a postcontrast T1-weighted exam, a T2-weighted fluid-attenuated inversion recovery exam, and at least one technician-derived tumor segmentation. The database included 729 unique patients (470 males and 259 females). Of these exams, 641 were used for training the DL system, and 100 were reserved for testing. We developed a platform to enable qualitative, blinded, controlled assessment of lesion segmentations made by technicians and the DL method. On this platform, 20 neuroradiologists performed 400 side-by-side comparisons of segmentations on 100 test cases. They scored each segmentation between 0 (poor) and 10 (perfect). Agreement between segmentations from technicians and the DL method was also evaluated quantitatively using the Dice coefficient, which produces values between 0 (no overlap) and 1 (perfect overlap). Results: The neuroradiologists gave technician and DL segmentations mean scores of 6.97 and 7.31, respectively ( p < 0.00007 ). The DL method achieved a mean Dice coefficient of 0.87 on the test cases. Conclusions: This was the first objective comparison of automated and human segmentation using a blinded controlled assessment study. Our DL system learned to outperform its "human teachers" and produced output that was better, on average, than its training data.

A novel etiology for craniospinal hypovolemia: a case of inferior vena cava obstruction.

The authors report on a patient with craniospinal hypovolemia and inferior vena cava obstruction, and describe how the two conditions may be linked. This unique report further advances the emerging literature on spinal CSF venous fistulae.

Estimation of Observer Performance for Reduced Radiation Dose Levels in CT: Eliminating Reduced Dose Levels That Are Too Low Is the First Step.

RATIONALE AND OBJECTIVES: This study aims to estimate observer performance for a range of dose levels for common computed tomography (CT) examinations (detection of liver metastases or pulmonary nodules, and cause of neurologic deficit) to prioritize noninferior dose levels for further analysis. MATERIALS AND METHODS: Using CT data from 131 examinations (abdominal CT, 44; chest CT, 44; head CT, 43), CT images corresponding to 4%-100% of the routine clinical dose were reconstructed with filtered back projection or iterative reconstruction. Radiologists evaluated CT images, marking specified targets, providing confidence scores, and grading image quality. Noninferiority was assessed using reference standards, reader agreement rules, and jackknife alternative free-response receiver operating characteristic figures of merit. Reader agreement required that a majority of readers at lower dose identify target lesions seen by the majority of readers at routine dose. RESULTS: Reader agreement identified dose levels lower than 50% and 4% to have inadequate performance for detection of hepatic metastases and pulmonary nodules, respectively, but could not exclude any low dose levels for head CT. Estimated differences in jackknife alternative free-response receiver operating characteristic figures of merit between routine and lower dose configurations found that only the lowest dose configurations tested (ie, 30%, 4%, and 10% of routine dose levels for abdominal, chest, and head CT examinations, respectively) did not meet criteria for noninferiority. At lower doses, subjective image quality declined before observer performance. Iterative reconstruction was only beneficial when filtered back projection did not result in noninferior performance. CONCLUSION: Opportunity exists for substantial radiation dose reduction using existing CT technology for common diagnostic tasks.

Evaluation of suspected aspirated beverage can pull tab: radiographs may not be enough.

A 67-year-old male presented to the emergency department with concern for accidental aspiration of an aluminum beverage can pull tab. Neck and chest radiographs did not reveal an aspirated foreign body. Despite ongoing complaint of dysgeusia and adamancy of aspiration by the patient, he was discharged to home without recommendation for further follow-up. Seven months later, a computed tomography (CT) scan of the chest performed as part of an unrelated lung cancer work up confirmed the presence of a left mainstem bronchus metallic foreign body compatible with a pull tab. This case report illustrates the poor negative predictive value of radiographs for a suspected aluminum foreign body and demonstrates the superiority of CT for this purpose. In such presentations it is imperative to have a low threshold for performing further diagnostic evaluation with CT due to the relatively high radiolucency of aluminum.

Tumefactive cerebral amyloid angiopathy mimicking CNS neoplasm.

OBJECTIVE: The tumefactive variant of cerebral amyloid angiopathy (CAA) is rare. In this article we describe imaging findings associated with this entity and evaluate the role of susceptibility MRI sequences in its diagnosis. CONCLUSION: Our findings suggest that in elderly patients, susceptibility sequences should be part of prebiopsy MRI for tumefactive lesions. Identification of characteristic diffuse microhemorrhages should prompt inclusion of CAA in the differential diagnosis, targeted biopsy of the cortex and leptomeninges, and pathologic staining for CAA.

Reduced immunoglobulin M is associated with sinus mucosal thickening, osteitis and sinus surgery in patients with common variable immunodeficiency.

BACKGROUND: Although common variable immunodeficiency (CVID) is associated with sinopulmonary disease, there are no previous systematic evaluations comparing computed tomographic (CT) sinus imaging with immunoglobulin measurements in patients with this condition. METHODS: We performed a retrospective review by a blinded observer using the Lund-Mackay numerical scoring scale as well as a visual scale for remodeling changes in the paranasal sinus bone on CT scans in CVID patients. RESULTS: The sinus CT scans of 19 subjects (9 males, 10 females; median age at diagnosis 34 years) are described. There was an inverse relationship between serum IgM and sinus mucosal thickening as described by the Lund-Mackay scale (R = -0.6398; p = 0.0032). Osteitis of the paranasal sinus bone was almost exclusively found in patients with a reduced serum IgM level of less than 25 mg/dl (p = 0.0074). CONCLUSION: This is the first study to show that sinus mucosal thickening on CT in patients with CVID is inversely related to serum IgM levels.

Blood and sputum eosinophil levels in asthma and their relationship to sinus computed tomographic findings.

OBJECTIVE: To investigate the relationship among blood and sputum eosinophil levels, sinus mucosal thickening, and osteitis in patients with asthma. PATIENTS AND METHODS: We conducted an observational study of 201 patients with asthma who underwent sinus computed tomographic (CT) imaging and induced sputum analysis at Mayo Clinic's site in Rochester, MN, from November 1, 2000, through December 31, 2005. Sinus CT scans were reviewed by an investigator blinded to patients' identity and chart information (J.B.H.) to assess for mucosal thickening. Each scan was assigned a CT score based on the Lund-Mackay staging scale. Approximately 20% of the scans were reviewed at random by a radiologist (N.G.C.) to ensure quality control. Bone changes consistent with osteitis were ascertained from radiology reports. Lung function was measured, and sputum was analyzed by conventional methods. RESULTS: Sinus CT scans revealed abnormalities in 136 (68%) of the 201 study patients. Severe mucosal thickening (CT score, > or = 12) was found in 60 patients (30%) and osteitis in 18 patients (9%). There was a positive correlation between CT scores and eosinophil levels in both peripheral blood (rho=0.45; 95% confidence interval, 0.33-0.56; P<.001) and induced sputum (rho=0.46; 95% confidence interval, 0.34-0.57; P<.001). Further, elevated blood and sputum eosinophil levels were associated with the presence of osteitis on CT scan and previous sinus surgery. CONCLUSION: Blood and sputum eosinophil levels in patients with asthma are directly correlated with sinus mucosal thickening and are associated with osteitis, lending further support to the hypothesis that asthma and chronic rhinosinusitis are mediated by similar inflammatory processes.

Correlation of histological findings from a large ciliochoroidal melanoma with CT perfusion and 3T MRI dynamic enhancement studies.

BACKGROUND: The initial use of a 64-slice computed tomography (CT) scanner for obtaining quantitative perfusion data from a large ciliochoroidal melanoma, and correlation with 3T magnetic resonance imaging (MRI) dynamic enhancement and tumor histology. METHODS: The CT perfusion scan was performed using 80 kVp, 250 mA and 1-sec rotation time for 40 sec. The analysis was performed using commercial perfusion analysis software with a prototype 3-dimensional motion correction tool. Dynamic contrast-enhanced 3-Tesla MRI measured the kinetics of enhancement to estimate the vascular permeability. The time-dependent enhancement patterns were obtained using the average signal intensity using Functool analysis software. The involved globe was enucleated and microscopic evaluation of the tumor was performed. RESULTS: The perfusion parameters blood flow, blood volume and permeability surface area product in the affected eye determined by CT perfusion analysis were 118 ml/100 ml/min, 11.3 ml/100 ml and 48 ml/100 ml/min. Dynamic MRI enhancement showed maximal intensity increase of 111%. The neoplasm was a ciliochoroidal spindle cell melanoma which was mitotically active (13 mitoses/40 hpf). Vascular loops and arcades were present throughout the tumor. The patient developed metastases within 9 months of presentation. CONCLUSION: Quantitative CT perfusion analysis of ocular tumors is feasible with motion correction software.

The clinical challenge of recognizing infratentorial empyema.

BACKGROUND: Infratentorial empyema is an uncommon complication of bacterial meningitis. Very little is known about its recognition and appropriate management. METHOD: We present a patient with infratentorial subdural empyema and compare findings with 41 cases with infratentorial empyema reported in the literature. RESULTS: Many patients with infratentorial empyema presented as subacute meningitis with neck stiffness and decreased consciousness. Diagnosis was often delayed. The minority had cerebellar findings and cranial nerve deficits. Clues to the diagnosis were presence of otitis, sinusitis, or mastoiditis and recent surgery for these disorders. The majority of patients underwent craniotomy; conservative treatment with antibiotics was associated with relapse of symptoms. The mortality rate was high especially in those with subdural empyema. CT failed to clearly visualize infratentorial subdural empyema in several reported cases. CONCLUSIONS: Infratentorial empyema is a life-threatening rare complication of bacterial meningitis. MRI, including diffusion-weighted imaging, is the preferred imaging technique in patients with suspected or proven bacterial meningitis and associated ear-nose-throat infection with deterioration in consciousness and neurologic signs that suggest a posterior fossa lesion. Neurosurgery should be regarded as first choice therapy.

Gliomatosis cerebri angiographically mimicking central nervous system angiitis: case report.

OBJECTIVE: The diagnosis of isolated central nervous system angiitis often requires both cerebral angiography and biopsy for diagnosis. CLINICAL PRESENTATION: We present a case of gliomatosis cerebri with demonstrated angiographic changes suggestive of a central nervous system vasculitis. INTERVENTION: A 47-year-old woman presented with a 2-week history of worsening headache and progressive drowsiness. Magnetic resonance imaging scans revealed confluent nonenhancing T2-weighted hyperintensity involving the frontal white matter bilaterally, hypothalamus, and both thalami. A four-vessel angiogram revealed diffuse arterial beading with stenoses of a right frontal middle cerebral artery branch and the distal posterior cerebral artery and anterior cerebral artery branches, bilaterally. The biopsy revealed a Grade 2 fibrillary astrocytoma consistent with gliomatosis cerebri. CONCLUSION: Gliomatosis cerebri can mimic central nervous system vasculitis angiographically. Perivascular infiltration by tumor cells may be responsible for these changes.

De novo development of a lesion with the appearance of a cavernous malformation adjacent to an existing developmental venous anomaly.

A case is presented in which a complex multicystic hemosiderin-containing lesion developed adjacent to a previously documented developmental venous anomaly (venous angioma). This lesion had the characteristic MR imaging appearance of a cavernous malformation. Follow-up MR imaging demonstrated a decrease in both the size and complexity of this lesion, which suggests at least a portion of the lesion was due to sequelae of hemorrhage. This case further supports the association of a de novo, hemosiderin-containing lesion in association with developmental venous anomaly. Implications of these findings are that the commonly seen "cavernous malformations" in association with developmental venous anomaly are acquired lesions, and not congenital in origin. A review of the literature discussing the etiology of cavernous malformations and their reported association with the developmental venous anomaly is provided.

Adult polyglucosan body disease: case description of an expanding genetic and clinical syndrome.

A non-Jewish patient is described who had adult polyglucosan body disease (APBD) and glycogen branching enzyme (GBE) deficiency without GBE mutation. A heterozygous polymorphism (Val160Ile) was found, and also discovered in 1 of 50 normal individuals. Magnetic resonance imaging demonstrated increased T2 signal in the midbrain, medullary olives, dentate nuclei, cerebellar peduncles, and internal and external capsules, with vermian atrophy. Both muscle and nerve biopsy revealed perivascular inflammatory infiltrates. These findings expand the clinical and genetic spectrum of APBD. Factors other than mutation of the expressed GBE gene may cause enzyme deficiency and varied expression and development of APBD.

MR imaging and diffusion-weighted imaging changes in metronidazole (Flagyl)-induced cerebellar toxicity.

We describe a case demonstrating reversible MR imaging findings, including diffusion-weighted imaging changes in association with metronidazole (Flagyl) toxicity. The diagnosis of metronidazole toxicity was made clinically and supported by the MR imaging findings. Quantitative apparent diffusion coefficient (ADC) maps demonstrated edema with associated increased ADC values within the dentate nuclei of the cerebellum on initial imaging. Follow-up imaging performed 8 weeks after cessation of metronidazole therapy demonstrated resolution of imaging findings, including diffusion changes.

Triple-dose contrast/magnetization transfer suppressed imaging of 'non-enhancing' brain gliomas.

PURPOSE: Triple-dose (TD) gadolinium contrast administration and magnetization transfer suppression (MTS) in brain magnetic resonance imaging (MRI) have proven to be useful for demonstrating additional enhancing lesions in some diseases. The purpose of this study was to determine if there is a subset of brain tumors that demonstrate contrast enhancement with TD and MTS that do not enhance with standard imaging and standard contrast dose. MATERIALS AND METHODS: Fifteen patients with either newly diagnosed primary brain tumor or brain tumor that had been followed for more than 2 years were enrolled. T1-weighted MTS images without IV contrast, with 0.1 mmol/kg without MTS (single-dose (SD) images), and with additional 0.2 mmol/kg gadolinium and MTS ('TD/MTS') were obtained. RESULTS: None of the patients had enhancement on SD images. Six patients had areas of enhancement on TD/MTS images ('exact' chi-squared p = 0.017). CONCLUSION: A statistically significant increased rate of contrast enhancement was found on TD/MTS images in patients whose tumors did not enhance at single dose without MTS. It is possible that small areas of enhancement seen only with TD/MTS might represent areas of higher-grade tumor.