Differentiating Imaging Features of Post-lobectomy Right Middle Lobe Torsion.

PURPOSE: The purpose of this study was to identify differences in imaging features between patients with confirmed right middle lobe (RML) torsion compared to those suspected yet without torsion. MATERIALS AND METHODS: This retrospective study entailing a search of radiology reports from April 1, 2014, to April 15, 2021, resulted in 52 patients with suspected yet without lobar torsion and 4 with confirmed torsion, supplemented by 2 additional cases before the search period for a total of 6 confirmed cases. Four thoracic radiologists (1 an adjudicator) evaluated chest radiographs and computed tomography (CT) examinations, and Fisher exact and Mann-Whitney tests were used to identify any significant differences in imaging features (P<0.05). RESULTS: A reversed halo sign was more frequent for all readers (P=0.001) in confirmed RML torsion than patients without torsion (83.3% vs. 0% for 3 readers, one the adjudicator). The CT coronal bronchial angle between RML bronchus and bronchus intermedius was larger (P=0.035) in torsion (121.28 degrees) than nontorsion cases (98.26 degrees). Patients with torsion had a higher percentage of ground-glass opacity in the affected lobe (P=0.031). A convex fissure towards the adjacent lobe on CT (P=0.009) and increased lobe volume on CT (P=0.001) occurred more often in confirmed torsion. CONCLUSION: A reversed halo sign, larger CT coronal bronchial angle, greater proportion of ground-glass opacity, fissural convexity, and larger lobe volume on CT may aid in early recognition of the rare yet highly significant diagnosis of lobar torsion.

Simultaneous Evaluation of Lung Anatomy and Ventilation Using 4D Respiratory-Motion-Resolved Ultrashort Echo Time Sparse MRI.

BACKGROUND: Computed tomography (CT) and spirometry are the current standard methods for assessing lung anatomy and pulmonary ventilation, respectively. However, CT provides limited ventilation information and spirometry only provides global measures of lung ventilation. Thus, a method that can enable simultaneous examination of lung anatomy and ventilation is of clinical interest. PURPOSE: To develop and test a 4D respiratory-resolved sparse lung MRI (XD-UTE: eXtra-Dimensional Ultrashort TE imaging) approach for simultaneous evaluation of lung anatomy and pulmonary ventilation. STUDY TYPE: Prospective. POPULATION: In all, 23 subjects (11 volunteers and 12 patients, mean age = 63.6 ± 8.4). FIELD STRENGTH/SEQUENCE: 3T MR; a prototype 3D golden-angle radial UTE sequence, a Cartesian breath-hold volumetric-interpolated examination (BH-VIBE) sequence. ASSESSMENT: All subjects were scanned using the 3D golden-angle radial UTE sequence during normal breathing. Ten subjects underwent an additional scan during alternating normal and deep breathing. Respiratory-motion-resolved sparse reconstruction was performed for all the acquired data to generate dynamic normal-breathing or deep-breathing image series. For comparison, BH-VIBE was performed in 12 subjects. Lung images were visually scored by three experienced chest radiologists and were analyzed by two observers who segmented the left and right lung to derive ventilation parameters in comparison with spirometry. STATISTICAL TESTS: Nonparametric paired two-tailed Wilcoxon signed-rank test; intraclass correlation coefficient, Pearson correlation coefficient. RESULTS: XD-UTE achieved significantly improved image quality compared both with Cartesian BH-VIBE and radial reconstruction without motion compensation (P < 0.05). The global ventilation parameters (a sum of the left and right lung measures) were in good correlation with spirometry in the same subjects (correlation coefficient = 0.724). There were excellent correlations between the results obtained by two observers (intraclass correlation coefficient ranged from 0.8855-0.9995). DATA CONCLUSION: Simultaneous evaluation of lung anatomy and ventilation using XD-UTE is demonstrated, which have shown good potential for improved diagnosis and management of patients with heterogeneous lung diseases. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:411-422.

Nonischemic Cardiomyopathies.

Computed tomography of the heart can characterize and differentiate various forms of nonischemic cardiomyopathy, which are covered individually in this article. With its excellent spatial and ever-improving temporal resolution, computed tomography scanning can delineate cardiac function, anatomy, and myocardial tissue characterization. Various cardiac computed tomography techniques can be tailored to the relevant clinical question, as discussed in the article. Although cardiac computed tomography scanning is not often the primary modality for myocardial evaluation, decreasing radiation doses and emerging applications make this fast and relatively economical examination a useful tool in the evaluation of the patient with cardiomyopathy.

Survey-Based Assessment of Patients' Understanding of Their Own Imaging Examinations.

PURPOSE: To perform a survey-based assessment of patients' knowledge of radiologic imaging examinations, including patients' perspectives regarding communication of such information. METHODS: Adult patients were given a voluntary survey before undergoing an outpatient imaging examination at our institution. Survey questions addressed knowledge of various aspects of the examination, as well as experiences, satisfaction, and preferences regarding communication of such knowledge. RESULTS: A total of 176 surveys were completed by patients awaiting CT (n = 45), MRI (n = 41), ultrasound (n = 46), and nuclear medicine (n = 44) examinations. A total of 97.1% and 97.8% of patients correctly identified the examination modality and the body part being imaged, respectively. A total of 45.8% correctly identified whether the examination entailed radiation; 51.1% and 71.4% of patients receiving intravenous or oral contrast, respectively, correctly indicated its administration. A total of 78.6% indicated that the ordering physician explained the examination in advance; among these, 72.1% indicated satisfaction with the explanation. A total of 21.8% and 20.5% indicated consulting the Internet, or friends and family, respectively, to learn about the examination. An overall understanding of the examination was reported by 70.8%. A total of 18.8% had unanswered questions about the examination, most commonly regarding examination logistics, contrast-agent usage, and when results would be available. A total of 52.9% were interested in discussing the examination with a radiologist in advance. Level of understanding was greatest for CT and least for nuclear medicine examinations, and lower when patients had not previously undergone the given examination. CONCLUSIONS: Patients' knowledge of their imaging examinations is frequently incomplete. The findings may motivate initiatives to improve patients' understanding of their imaging examinations, enhancing patient empowerment and contributing to patient-centered care.

Schwann cells seeded in acellular nerve grafts improve functional recovery.

INTRODUCTION: This study evaluated whether Schwann cells (SCs) from different nerve sources transplanted into cold-preserved acellular nerve grafts (CP-ANGs) would improve functional regeneration compared with nerve isografts. METHODS: SCs isolated and expanded from motor and sensory branches of rat femoral and sciatic nerves were seeded into 14mm CP-ANGs. Growth factor expression, axonal regeneration, and functional recovery were evaluated in a 14-mm rat sciatic injury model and compared with isografts. RESULTS: At 14 days, motor or sensory-derived SCs increased expression of growth factors in CP-ANGs versus isografts. After 42 days, histomorphometric analysis found CP-ANGs with SCs and isografts had similar numbers of regenerating nerve fibers. At 84 days, muscle force generation was similar for CP-ANGs with SCs and isografts. SC source did not affect nerve fiber counts or muscle force generation. CONCLUSIONS: SCs transplanted into CP-ANGs increase functional regeneration to isograft levels; however SC nerve source did not have an effect.

Computed tomography of blunt and penetrating diaphragmatic injury: sensitivity and inter-observer agreement of CT Signs.

Diaphragmatic injury is an uncommon but clinically important entity in the setting of trauma. Computed tomography (CT) is widely used to evaluate hemodynamically stable trauma patients. While prior studies have identified CT signs of diaphragm injury in blunt or penetrating trauma, no study has directly compared signs across these two types of injuries. We identified patients with surgically proven diaphragm injuries who underwent CT at presentation. Three reviewers examined each for 12 signs of diaphragm injury, as well as for an overall impression of diaphragm injury. We reviewed a total of 84 patients (37 % blunt trauma, 63 % penetrating). The initial interpreting radiologists discovered 77 % of blunt and 47 % of penetrating injuries (p = 0.01). We found that the majority of signs of diaphragmatic injury were split between those common in blunt trauma and those common in penetrating trauma, with minimal overlap. The presence of at least one blunt injury sign has 90 % sensitivity for diaphragm injury in blunt trauma; the presence of a wound tract traversing the diaphragm has 92 % sensitivity in penetrating trauma. Inter-observer reliability of these signs is also high (κ > 0.65). Penetrating diaphragm injuries present a different spectrum of imaging findings from those in blunt trauma and are underdiagnosed at CT; looking for a wound tract traversing the diaphragm is highly sensitive for diaphragm injury in these cases. Signs of organ or diaphragm fragment displacement are sensitive for blunt diaphragm injuries, consistent with these injuries being caused by increased intra-abdominal pressure.

A transgenic rat expressing green fluorescent protein (GFP) in peripheral nerves provides a new hindlimb model for the study of nerve injury and regeneration.

BACKGROUND: In order to evaluate nerve regeneration in clinically relevant hindlimb surgical paradigms not feasible in fluorescent mice models, we developed a rat that expresses green fluorescent protein (GFP) in neural tissue. METHODS: Transgenic Sprague-Dawley rat lines were created using pronuclear injection of a transgene expressing GFP under the control of the thy1 gene. Nerves were imaged under fluorescence microscopy and muscles were imaged with confocal microscopy to determine GFP expression following sciatic nerve crush, transection and direct suturing, and transection followed by repair with a nerve isograft from nonexpressing littermates. RESULTS: In each surgical paradigm, fluorescence microscopy demonstrated the loss and reappearance of fluorescence with regeneration of axons following injury. Nerve regeneration was confirmed with imaging of Wallerian degeneration followed by reinnervation of extensor digitorum longus (EDL) muscle motor endplates using confocal microscopy. CONCLUSION: The generation of a novel transgenic rat model expressing GFP in neural tissue allows in vivo imaging of nerve regeneration and visualization of motor endplate reinnervation. This rat provides a new model for studying peripheral nerve injury and regeneration over surgically relevant distances.