Reduced gray-white matter contrast localizes the motor cortex on double inversion recovery (DIR) 3T MRI.

PURPOSE: Reduced gray-white matter contrast along the central sulcus has been described on T1- and T2-weighted magnetic resonance imaging (MRI). The purpose of this study was to assess the gray-white matter contrast of the motor cortex on double inversion recovery (DIR), a sequence with superior gray-white matter differentiation. METHODS: The gray-white matter signal on DIR was retrospectively compared to T1-weighted magnetization-prepared rapid gradient echo (T1-MPRAGE) using normal (n = 25) and abnormal (n = 25) functional MRI (fMRI) exams. Quantitative gray-white matter contrast ratios (CR) of the precentral and adjacent gyri were obtained on normal exams. Two neuroradiologists qualitatively rated reduced gray-white matter contrast of the hemispheres of both normal and abnormal exams. Hand motor functional mapping was used as a reference. RESULTS: In normal hemispheres (n = 50), the mean CR was significantly lower on DIR (0.44) vs T1-MPRAGE (0.63, p < 0.001). Reduced gray-white matter contrast was categorized as "definitely present" more frequently on DIR than T1-MPRAGE by reviewers in both normal (n = 50; reviewer 1 DIR 88% and MPRAGE 68%, p = 0.02; reviewer 2 DIR 86% and T1-MPRAGE 64%; p=0.01) and abnormal hemispheres (n = 50; reviewer 1 DIR 80% and T1-MPRAGE 38%, p < 0.001; reviewer 2 DIR 74% and T1-MPRAGE 46%, p = 0.005). CONCLUSION: Reduced gray-white matter contrast of the motor cortex is more pronounced on DIR compared to T1-MPRAGE on quantitative and qualitative assessments of normal MRI exams. In abnormal cases, reviewers more definitively identified the motor cortex on DIR. In cases with distorted brain anatomy, DIR may be a useful adjunct sequence to localize the motor cortex.

Reporting on Renal Masses, Recommendations for Terminology, and Sample Templates.

Given the incidence of small renal masses, from benign cysts to malignancy, most radiologists encounter these lesions multiple times during their career. Radiologists have an opportunity to provide critical data that will further refine the understanding of the impact of these masses on patient outcomes. This article summarizes and describes recent updates and understanding of the critical observations and descriptors of renal masses. The templates and glossary of terms presented in this review article facilitate the radiology reporting of such data elements, giving radiologists the opportunity to improve diagnostic accuracy and influence management of small renal masses.

Spontaneous non-aneurysmal subarachnoid hemorrhage in Takayasu arteritis: a case implicating hyperperfusion and cerebral dysautoregulation.

Takayasu arteritis (TA) is a systemic chronic inflammatory large-vessel vasculitis that affects the aorta, its major branches, and the pulmonary arteries. In this report, we describe a case of a young female with TA presenting with spontaneous subarachnoid hemorrhage (SAH), an unusual manifestation of the disease. Magnetic resonance angiography (MRA) of the head and neck demonstrates multifocal carotid and vertebral arterial stenoses, but no aneurysm or vascular malformation to account for SAH. A novel and unexpected finding in this case was increased cerebral perfusion in the right frontotemporal parenchyma and transient abnormally reduced augmentation of flow in response to the cerebral vasodilator acetazolamide. The etiology of SAH thus may be related to hyperperfusion and loss of cerebrovascular autoregulation leading to small vessel damage.

Combined task activation display as an effective method to teach introductory fMRI users.

RATIONALE AND OBJECTIVES: Interpreting functional magnetic resonance imaging (fMRI) can be an overwhelming and challenging task for trainees, particularly when post processing, synthesizing and interpreting data from multiple language paradigms. Currently, there is no established best method for teaching fMRI interpretation to new trainees. The purpose of our study is to compare the use of combined task activation display (CTAD) and conventional display of fMRI language paradigms as an effective method to teach fMRI to the introductory learner. MATERIALS AND METHODS: Following IRB approval, 43 unique cases (with 10 repeat cases to assess intra-reader variability) were identified based on the inclusion/exclusion criteria. Eight radiology trainees, without prior exposure to fMRI, were asked to determine language lateralization based on activation of Wernicke's area, Broca's area, and the pre-supplementary motor area. Prior to trainee interpretation, a 15-minute training session was conducted to describe the expected anatomic locations of the language centers. Trainees were asked to determine language dominance using either the CTAD or conventional methods. Following a 6-week washout period, the same eight trainees were asked to interpret the cases using the opposite interpretation approach. RESULTS: Interpreting fMRI with the CTAD method significantly increased trainee accuracy (85.4% vs 70.9% p < 0.001) and trainee confidence (4.3 vs 3.6 p < 0.001), while decreasing time to interpretation (mean difference of 29 min), and intra-reader variability when compared to the conventional approach. CONCLUSION: Combined task activation display is an effective method to teach fMRI to introductory learners.

Radiology Reading Room Huddles: Our Initial Experience.

OBJECTIVE. The objective of our study was to adapt the safety, methods, equipment, supplies, and associates, termed "S-MESA," communication tool from daily management huddles and implement it in radiology reading rooms to address the complexities of daily communications. We collected data on huddle logistics and perceived value from radiologists at an academic institution. MATERIALS AND METHODS. We constructed a 16-item survey composed of multiple-choice questions (single answer and multiple answers), statements requiring Likert scale ratings (from 1 [strongly disagree] to 5 [strongly agree]), and items requiring free text responses. The survey was distributed to 244 radiologists. Answers were collected over a 6-week period. RESULTS. The response rate was 41% (101/244). The majority of huddles were performed sometimes (59%) or daily or nearly daily (25%), and most lasted 5 minutes or less (83%), which was perceived as "just right" (87.5%). The components discussed more frequently in the huddle were availability (33.5%) and time goals (27%). Task review (19%) and miscellaneous (14%) were not as common. Huddles were valued for facilitating communication and better organizing the workday. CONCLUSION. Reading room huddles are feasible and perceived as useful. Moving forward, we are planning to integrate reading room huddles with multitier system huddles and include items that are of specific interest to radiology trainees.

Alternative community compositional and dynamical states: the dual consequences of assembly history.

1. Much work on ecological consequences of community assembly history has focused on the formation of history-induced alternative stable equilibria. We hypothesize that assembly history may affect not only community composition but also population dynamics, with assembled communities differing in species composition potentially residing in different dynamical states. 2. We provided an empirical test of the aforementioned hypothesis using a laboratory microcosm experiment that manipulated both the colonization order of three bacterivorous protist species in the presence of a protist predator and environmental productivity. 3. Both priority effects and random divergence emerged, resulting in two different community compositional states: one characterized by the dominance of one prey species and the other by the extinction of the same prey. While communities in the former state exhibited noncyclic dynamics, the majority of communities in the latter state exhibited cyclic dynamics driven by the interaction between another prey and the predator. 4. Temporal variability of total prey community biovolume consequently differed among communities with different histories. 5. Changing productivity altered priority effects on the structure and dynamics of communities experiencing only certain histories. 6. Our results support the dual (compositional and dynamical) consequences of assembly history and emphasize the importance of incorporating the dynamical view into the field of community assembly.

Predation alters relationships between biodiversity and temporal stability.

Abstract: Ecologists disagree on how diversity affects stability. At the heart of the controversy is the relationship between diversity and population stability, with conflicting findings from both theoretical and empirical studies. To help reconcile these results, we propose that this relationship may depend on trophic complexity, such that positive relations tend to emerge in multitrophic but not single-trophic communities. This hypothesis is based on the premise that stabilizing weak trophic interactions restrain population oscillations associated with strong trophic interactions in diverse multitrophic communities. We tested this hypothesis using simple freshwater bacterivorous protist communities differing in diversity with and without a predatory protist species. Coupling weak and strong trophic interactions reduced population temporal variability of the strong-interacting species, supporting the stabilizing role of weak interactions. In keeping with our hypothesis, predation altered the overall effect of diversity on population temporal stability and, in particular, caused a reversal of the diversity-stability relationship (negative without predators and positive with predators) for the strong-interacting species. A similar role of predation was also observed when examining the relationship between diversity and temporal stability of community biomass. Together, these findings demonstrated strong interactive effects of trophic interactions and diversity on temporal stability of population and community properties.