Faculty Bibliography

Two new 3T MR imaging contrast methods, track density imaging and echo modulation curve T2 mapping, were combined with simultaneous multisection acquisition to reveal exquisite anatomic detail at 7 canonical levels of the brain stem. Compared with conventional MR imaging contrasts, many individual brain stem tracts and nuclear groups were directly visualized for the first time at 3T. This new approach is clinically practical and feasible (total scan time = 20 minutes), allowing better brain stem anatomic localization and characterization.

Objectives: Classic radiological presentation of Wilson's disease (WD) with face of the "giant panda" is typically used to distinguish WD from other extrapyramidal disorders. Central pontine myelinolysis like (CPMlike) changes in WD are rarely reported and are distinct from the classic commonly known osmotic demyelination. Although CPM-like changes on MRI in young WD patients are common, there are no published reports of such radiological picture in the exceptional cases of late onset WD. We report on a late onset WD with sequential MRI changes with response to de-coppering therapy. Methods: A 64 year-old male with pulmonary sarcoidosis presented with a two-year history of worsening axial ataxia, postural, kinetic and rest tremors and cognitive decline. His examination was also significant for generalized hyperreflexia, Babinski sign and the presence of Kayser-Fleischer rings. WD diagnosis was confirmed with low ceruloplasmin and with the presence of homozygous mutation in the ATP7B gene. Results: MRI at symptom onset showed diffuse T2/FLAIR hyperintensity in the pons which was contiguous with hyperintensity of the midbrain, as well as focal hyperintensity in left thalamus and generalized cortical atrophy. Following nine months of chelation with trientine, partial resolution of the T2 hyperintensity in the pons was observed, while thalamus hyperintensity became less conspicuous. Conclusions: WD must be considered in all patients that present with hepatic or neurological symptoms without definitive diagnosis, regardless of age. WD and CPM-like radiological changes in older adult WD patients may be under-recognized, but genetic confirmation and clinical exam findings should guide treatment

The purpose of the present review is to discuss and display orbital lesions that demonstrate hypo-intense signal on T2-weighted images (T2WI). The physical basis for hypo-intense signal on T2WI produced by various substances is discussed. Orbital lesions that are hypo-intense on T2WI are subsequently reviewed, including a discussion on their composition as well as relevant clinical and imaging clues that may aid in their diagnosis.

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.

BACKGROUND AND PURPOSE: The pituitary gland is located outside of the blood-brain barrier. Dynamic T1 weighted contrast enhanced sequence is considered to be the gold standard to evaluate this region. However, it does not allow assessment of intrinsic permeability properties of the gland. Our aim was to demonstrate the utility of radial volumetric interpolated brain examination with the golden-angle radial sparse parallel technique to evaluate permeability characteristics of the individual components (anterior and posterior gland and the median eminence) of the pituitary gland and areas of differential enhancement and to optimize the study acquisition time. MATERIALS AND METHODS: A retrospective study was performed in 52 patients (group 1, 25 patients with normal pituitary glands; and group 2, 27 patients with a known diagnosis of microadenoma). Radial volumetric interpolated brain examination sequences with golden-angle radial sparse parallel technique were evaluated with an ROI-based method to obtain signal-time curves and permeability measures of individual normal structures within the pituitary gland and areas of differential enhancement. Statistical analyses were performed to assess differences in the permeability parameters of these individual regions and optimize the study acquisition time. RESULTS: Signal-time curves from the posterior pituitary gland and median eminence demonstrated a faster wash-in and time of maximum enhancement with a lower peak of enhancement compared with the anterior pituitary gland (P < .005). Time-optimization analysis demonstrated that 120 seconds is ideal for dynamic pituitary gland evaluation. In the absence of a clinical history, differences in the signal-time curves allow easy distinction between a simple cyst and a microadenoma. CONCLUSIONS: This retrospective study confirms the ability of the golden-angle radial sparse parallel technique to evaluate the permeability characteristics of the pituitary gland and establishes 120 seconds as the ideal acquisition time for dynamic pituitary gland imaging.

BACKGROUND AND PURPOSE: Although NAA is often used as a marker of neuronal health and integrity in neurologic disorders, its normal response to physiologic challenge is not well-established and its changes are almost always attributed exclusively to brain pathology. The purpose of this study was to test the hypothesis that the neuronal cell marker NAA, often used to assess neuronal health and integrity in neurologic disorders, is not confounded by (possibly transient) physiologic changes. Therefore, its decline, when observed by using 1H-MR spectroscopy, can almost always be attributed exclusively to brain pathology. MATERIALS AND METHODS: Twelve healthy young male adults underwent a transient hypercapnia challenge (breathing 5% CO2 air mixture), a potent vasodilator known to cause a substantial increase in CBF and venous oxygenation. We evaluated their whole-brain NAA by using nonlocalizing proton MR spectroscopy, venous oxygenation with T2-relaxation under spin-tagging MR imaging, CBF with pseudocontinuous arterial spin-labeling, and the cerebral metabolic rate of oxygen, during normocapnia (breathing room air) and hypercapnia. RESULTS: There was insignificant whole-brain NAA change (P = .88) from normocapnia to hypercapnia and back to normocapnia in this cohort, as opposed to highly significant increases: 28.0 +/- 10.3% in venous oxygenation and 49.7 +/- 16.6% in global CBF (P < 10-4); and a 6.4 +/- 10.9% decrease in the global cerebral metabolic rate of oxygen (P = .04). CONCLUSIONS: Stable whole-brain NAA during normocapnia and hypercapnia, despite significant global CBF and cerebral metabolic rate of oxygen changes, supports the hypothesis that global NAA changes are insensitive to transient physiology. Therefore, when observed, they most likely reflect underlying pathology resulting from neuronal cell integrity/viability changes, instead of a response to physiologic changes.

OBJECTIVES: Contrast-enhanced fat-suppressed T1-weighted-2D-TSE and MPRAGE sequence with water excitation are routinely obtained to evaluate orbit pathology. However, these sequences can be marred by artifacts. The Radial-VIBE sequence is a motion-robust fat-suppressed T1W sequence which has demonstrated value in pediatric and body imaging. The purpose of our study is to evaluate its role in assessing the orbit, and to compare it with routinely acquired sequences. METHODS: A HIPAA-compliant and IRB-approved retrospective study was performed in 46 patients (age range: 1-81 years) who underwent orbit studies on a 1.5-T MRI using contrast-enhanced Radial-VIBE, MPRAGE and 2D-TSE sequences. Two radiologists blinded to the sequence analyzed evaluated multiple parameters of image quality including motion artifact, degree of fat-suppression, clarity of choroidal enhancement, intraorbital vessels, extraocular muscles, optic nerves, brain parenchyma and evaluation of pathology. Each parameter was assessed on a 5-point scale, with a higher score indicating the more optimal exam. Mix-model analysis of variance and interobserver variability were assessed. RESULTS: Radial-VIBE demonstrated superior quality (p<0.001) for all orbit parameters when compared to MPRAGE and 2D-TSE. Interobserver agreement demonstrated average fair-to -good agreement for: degree of motion artifact (0.745), fat suppression (0.678), clarity of choroidal enhancement (0.688), vessels (0.655), extraocular muscles (0.675), optic nerves (0.518), brain parenchyma (0.710), and evaluation of pathology (0.590). CONCLUSION: Radial-VIBE sequence demonstrates superior image quality when evaluating the orbits as compared to conventional MPRAGE and 2D-TSE sequences. Advances in knowledge: Radial-VIBE employs unique non-Cartesian k-space sampling in a radial or spoke-wheel fashion which provides superior image quality improving diagnostic capability in evaluation of the orbits.

OBJECTIVE: Several criteria for time-consuming volumetric measurements of progressive supranuclear palsy Richardson syndrome subtype (PSP-RS) have been proposed. These often require image reconstruction in different planes for proper assessment. The purpose of this study was to evaluate the cerebral peduncle angle as a simple and reproducible measure of midbrain atrophy in patients with PSP-RS. MATERIALS AND METHODS: The records of 15 patients with PSP-RS were retrospectively identified. The records of 31 age-matched healthy control subjects, 15 patients with multiple-system atrophy, and 22 patients with Parkinson disease were included for comparison. Two neuroradiologists individually assessed these studies for midbrain atrophy by evaluating the cerebral peduncle angle, that is, the angle between the two cerebral peduncles. RESULTS: The cerebral peduncle angle measurements were 62.1 degrees (SD, 6.8 degrees ) in PSP-RS patients, 51.2 degrees (SD, 10.1 degrees ) in healthy control subjects, 55.7 degrees (SD, 11.6 degrees ) in patients with multiple-system atrophy, and 53.7 degrees (SD, 8.5 degrees ) in patients with Parkinson disease. A statistically significant difference was found in the cerebral peduncle angle measurements (observer 1, p = 0.015; observer 2, p = 0.004) between the PSP-RS patients and the other subgroups. Bland-Altman analysis showed a bias of 0.6 degrees (95% limits of agreement, 6.9 degrees , -5.8 degrees ), and intraobserver variability analysis showed a bias of 0.5 degrees (4.1 degrees , -3 degrees ). CONCLUSION: The cerebral peduncle angle is a simple, easy-to-calculate, and reproducible measure of midbrain atrophy. It is a useful criterion for differentiating patients with PSP-RS from healthy persons and from patients with multiple-system atrophy or Parkinson disease.

BACKGROUND AND PURPOSE: The Circle of Willis (COW) is the main collateral system between the bilateral carotid systems and the posterior circulation. COW normal variants are encountered in up to 62% of subjects. We hypothesize that, in patients with carotid artery stenosis, the presence of COW variants is a risk factor for leukoaraiosis. MATERIALS AND METHODS: Forty-seven patients (mean age 72.1 +/- 9 years, males = 39) with carotid artery stenosis admitted for carotid endarterectomy were included and underwent an admission brain MRI/MRA. Two neuroradiologists evaluated the COW variants. FLAIR-leukoaraiosis lesion-volume was performed using a semiautomated segmentation technique. Mann-Whitney and Pearson correlations were conducted to identify the correlation between the FLAIR-leukoaraiosis lesion-volume and the COW variants. ROC analysis was performed to evaluate the AUC of FLAIR-leukoaraiosis lesion-volume and presence/absence of COW variants. RESULTS: Pearson correlation demonstrated that the leukoaraiosis lesion-volume is significantly associated with the COW variants number (rho = .358, P = .0215). When patients were dicotomized in two subgroups, with and without COW variants, the lesion-volume was significantly higher in the variants group (P = .0405). The ROC curve analysis showed an AUC of .688 (SE = .083, 95%CI = .525-.823) with a statistically significant P = .0225, between the presence of COW variants and the FLAIR-leukoaraiosis lesion-volume. CONCLUSION: The presence and the number of COW variants are associated with a higher leukoaraiosis volume in patients with significant internal carotid artery stenosis.