Quantitative Characterization of Respiratory Patterns on Dynamic Higher Temporal Resolution MRI to Stratify Postacute Covid-19 Patients by Cardiopulmonary Symptom Burden.

BACKGROUND: Postacute Covid-19 patients commonly present with respiratory symptoms; however, a noninvasive imaging method for quantitative characterization of respiratory patterns is lacking. PURPOSE: To evaluate if quantitative characterization of respiratory pattern on free-breathing higher temporal resolution MRI stratifies patients by cardiopulmonary symptom burden. STUDY TYPE: Prospective analysis of retrospectively acquired data. SUBJECTS: A total of 37 postacute Covid-19 patients (25 male; median [interquartile range (IQR)] age: 58 [42-64] years; median [IQR] days from acute infection: 335 [186-449]). FIELD STRENGTH/SEQUENCE: 0.55 T/two-dimensional coronal true fast imaging with steady-state free precession (trueFISP) at higher temporal resolution. ASSESSMENT: Patients were stratified into three groups based on presence of no (N = 11), 1 (N = 14), or ≥2 (N = 14) cardiopulmonary symptoms, assessed using a standardized symptom inventory within 1 month of MRI. An automated lung postprocessing workflow segmented each lung in each trueFISP image (temporal resolution 0.2 seconds) and respiratory curves were generated. Quantitative parameters were derived including tidal lung area, rates of inspiration and expiration, lung area coefficient of variability (CV), and respiratory incoherence (departure from sinusoidal pattern) were. Pulmonary function tests were recorded if within 1 month of MRI. Qualitative assessment of respiratory pattern and lung opacity was performed by three independent readers with 6, 9, and 23 years of experience. STATISTICAL TESTS: Analysis of variance to assess differences in demographic, clinical, and quantitative MRI parameters among groups; univariable analysis and multinomial logistic regression modeling to determine features predictive of patient symptom status; Akaike information criterion to compare the quality of regression models; Cohen and Fleiss kappa (κ) to quantify inter-reader reliability. Two-sided 5% significance level was used. RESULTS: Tidal area and lung area CV were significantly higher in patients with two or more symptoms than in those with one or no symptoms (area: 15.4 cm2 vs. 12.9 cm2 vs. 12.8 cm2 ; CV: 0.072, 0.067, and 0.058). Respiratory incoherence was significantly higher in patients with two or more symptoms than in those with one or no symptoms (0.05 vs. 0.043 vs. 0.033). There were no significant differences in patient age (P = 0.19), sex (P = 0.88), lung opacity severity (P = 0.48), or pulmonary function tests (P = 0.35-0.97) among groups. Qualitative reader assessment did not distinguish between groups and showed slight inter-reader agreement (κ = 0.05-0.11). DATA CONCLUSION: Quantitative respiratory pattern measures derived from dynamic higher-temporal resolution MRI have potential to stratify patients by symptom burden in a postacute Covid-19 cohort. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 3.

Comparison of a Deep Learning-Accelerated vs. Conventional T2-Weighted Sequence in Biparametric MRI of the Prostate.

BACKGROUND: Demand for prostate MRI is increasing, but scan times remain long even in abbreviated biparametric MRIs (bpMRI). Deep learning can be leveraged to accelerate T2-weighted imaging (T2WI). PURPOSE: To compare conventional bpMRIs (CL-bpMRI) with bpMRIs including a deep learning-accelerated T2WI (DL-bpMRI) in diagnosing prostate cancer. STUDY TYPE: Retrospective. POPULATION: Eighty consecutive men, mean age 66 years (47-84) with suspected prostate cancer or prostate cancer on active surveillance who had a prostate MRI from December 28, 2020 to April 28, 2021 were included. Follow-up included prostate biopsy or stability of prostate-specific antigen (PSA) for 1 year. FIELD STRENGTH AND SEQUENCES: A 3 T MRI. Conventional axial and coronal T2 turbo spin echo (CL-T2), 3-fold deep learning-accelerated axial and coronal T2-weighted sequence (DL-T2), diffusion weighted imaging (DWI) with b = 50 sec/mm2 , 1000 sec/mm2 , calculated b = 1500 sec/mm2 . ASSESSMENT: CL-bpMRI and DL-bpMRI including the same conventional diffusion-weighted imaging (DWI) were presented to three radiologists (blinded to acquisition method) and to a deep learning computer-assisted detection algorithm (DL-CAD). The readers evaluated image quality using a 4-point Likert scale (1 = nondiagnostic, 4 = excellent) and graded lesions using Prostate Imaging Reporting and Data System (PI-RADS) v2.1. DL-CAD identified and assigned lesions of PI-RADS 3 or greater. STATISTICAL TESTS: Quality metrics were compared using Wilcoxon signed rank test, and area under the receiver operating characteristic curve (AUC) were compared using Delong's test. SIGNIFICANCE: P = 0.05. RESULTS: Eighty men were included (age: 66 ± 9 years; 17/80 clinically significant prostate cancer). Overall image quality results by the three readers (CL-T2, DL-T2) are reader 1: 3.72 ± 0.53, 3.89 ± 0.39 (P = 0.99); reader 2: 3.33 ± 0.82, 3.31 ± 0.74 (P = 0.49); reader 3: 3.67 ± 0.63, 3.51 ± 0.62. In the patient-based analysis, the reader results of AUC are (CL-bpMRI, DL-bpMRI): reader 1: 0.77, 0.78 (P = 0.98), reader 2: 0.65, 0.66 (P = 0.99), reader 3: 0.57, 0.60 (P = 0.52). Diagnostic statistics from DL-CAD (CL-bpMRI, DL-bpMRI) are sensitivity (0.71, 0.71, P = 1.00), specificity (0.59, 0.44, P = 0.05), positive predictive value (0.23, 0.24, P = 0.25), negative predictive value (0.88, 0.88, P = 0.48). CONCLUSION: Deep learning-accelerated T2-weighted imaging may potentially be used to decrease acquisition time for bpMRI. EVIDENCE LEVEL: 3. TECHNICAL EFFICACY: Stage 2.

Respiratory Motion Management in Abdominal MRI: Radiology In Training.

A 96-year-old woman had a suboptimal evaluation of liver observations at abdominal MRI due to significant respiratory motion. State-of-the-art strategies to minimize respiratory motion during clinical abdominal MRI are discussed.

Solitary Pulmonary Nodule Evaluation: Pearls and Pitfalls.

Lung nodules are frequently encountered while interpreting chest CTs and are challenging to detect, characterize, and manage given they can represent both benign or malignant etiologies. An understanding of features associated with malignancy and causes of interpretive pitfalls is helpful to avoid misdiagnoses. This review addresses pertinent topics related to the etiologies for missed lung nodules on radiography and CT. Additionally, CT imaging technical pitfalls and challenges in addition to issues in the evaluation of nodule morphology, attenuation, and size will be discussed. Nodule management guidelines will be addressed as well as recent investigations that further our understanding of lung nodules.

Multicenter Evaluation of Multiparametric MRI Clear Cell Likelihood Scores in Solid Indeterminate Small Renal Masses.

Background Solid small renal masses (SRMs) (≤4 cm) represent benign and malignant tumors. Among SRMs, clear cell renal cell carcinoma (ccRCC) is frequently aggressive. When compared with invasive percutaneous biopsies, the objective of the proposed clear cell likelihood score (ccLS) is to classify ccRCC noninvasively by using multiparametric MRI, but it lacks external validation. Purpose To evaluate the performance of and interobserver agreement for ccLS to diagnose ccRCC among solid SRMs. Materials and Methods This retrospective multicenter cross-sectional study included patients with consecutive solid (≥25% approximate volume enhancement) SRMs undergoing multiparametric MRI between December 2012 and December 2019 at five academic medical centers with histologic confirmation of diagnosis. Masses with macroscopic fat were excluded. After a 1.5-hour training session, two abdominal radiologists per center independently rendered a ccLS for 50 masses. The diagnostic performance for ccRCC was calculated using random-effects logistic regression modeling. The distribution of ccRCC by ccLS was tabulated. Interobserver agreement for ccLS was evaluated with the Fleiss κ statistic. Results A total of 241 patients (mean age, 60 years ± 13 [SD]; 174 men) with 250 solid SRMs were evaluated. The mean size was 25 mm ± 8 (range, 10-39 mm). Of the 250 SRMs, 119 (48%) were ccRCC. The sensitivity, specificity, and positive predictive value for the diagnosis of ccRCC when ccLS was 4 or higher were 75% (95% CI: 68, 81), 78% (72, 84), and 76% (69, 81), respectively. The negative predictive value of a ccLS of 2 or lower was 88% (95% CI: 81, 93). The percentages of ccRCC according to the ccLS were 6% (range, 0%-18%), 38% (range, 0%-100%), 32% (range, 60%-83%), 72% (range, 40%-88%), and 81% (range, 73%-100%) for ccLSs of 1-5, respectively. The mean interobserver agreement was moderate (κ = 0.58; 95% CI: 0.42, 0.75). Conclusion The clear cell likelihood score applied to multiparametric MRI had moderate interobserver agreement and differentiated clear cell renal cell carcinoma from other solid renal masses, with a negative predictive value of 88%. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Mileto and Potretzke in this issue.

Outcomes of Incidental Lung Nodules With Structured Recommendations and Electronic Tracking.

OBJECTIVE: To evaluate the impact of structured recommendations on follow-up completion for incidental lung nodules (ILNs). METHODS: Patients with ILNs before and after implementation of structured Fleischner recommendations and electronic tracking were sampled randomly. The cohorts were compared for imaging follow-up. Multivariable logistic regression was used to assess appropriate follow-up and loss to follow-up, with independent variables including use of structured recommendations or tracking, age, sex, race, ethnicity, setting of the index test (inpatient, outpatient, emergency department), smoking history, and nodule features. RESULTS: In all, 1,301 patients met final inclusion criteria, including 255 patients before and 1,046 patients after structured recommendations or tracking. Baseline differences were found in the pre- and postintervention groups, with smaller ILNs and younger age after implementing structured recommendations. Comparing pre- versus postintervention outcomes, 40.0% (100 of 250) versus 29.5% (309 of 1,046) of patients had no follow-up despite Fleischner indications for imaging (P = .002), and among the remaining patients, 56.6% (82 of 145) versus 75.0% (553 of 737) followed up on time (P < .001). Delayed follow-up was more frequent before intervention. Differences postintervention were mostly accounted for by nodules ≤8 mm in the outpatient setting (P < .001). In multivariable analysis, younger age, White race, outpatient setting, and larger nodule size showed significant association with appropriate follow-up completion (P < .015), but structured recommendations did not. Similar results applied for loss to follow-up. DISCUSSION: Consistent use of structured reporting is likely key to mitigate selection bias when benchmarking rates of appropriate follow-up of ILN. Emergency department patients and inpatients are at high risk of missed or delayed follow-up despite structured recommendations.

Diagnostic abdominal MR imaging on a prototype low-field 0.55 T scanner operating at two different gradient strengths.

PURPOSE: To develop a protocol for abdominal imaging on a prototype 0.55 T scanner and to benchmark the image quality against conventional 1.5 T exam. METHODS: In this prospective IRB-approved HIPAA-compliant study, 10 healthy volunteers were recruited and imaged. A commercial MRI system was modified to operate at 0.55 T (LF) with two different gradient performance levels. Each subject underwent non-contrast abdominal examinations on the 0.55 T scanner utilizing higher gradients (LF-High), lower adjusted gradients (LF-Adjusted), and a conventional 1.5 T scanner. The following pulse sequences were optimized: fat-saturated T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and Dixon T1-weighted imaging (T1WI). Three readers independently evaluated image quality in a blinded fashion on a 5-point Likert scale, with a score of 1 being non-diagnostic and 5 being excellent. An exact paired sample Wilcoxon signed-rank test was used to compare the image quality. RESULTS: Diagnostic image quality (overall image quality score ≥ 3) was achieved at LF in all subjects for T2WI, DWI, and T1WI with no more than one unit lower score than 1.5 T. The mean difference in overall image quality score was not significantly different between LF-High and LF-Adjusted for T2WI (95% CI - 0.44 to 0.44; p = 0.98), DWI (95% CI - 0.43 to 0.36; p = 0.92), and for T1 in- and out-of-phase imaging (95%C I - 0.36 to 0.27; p = 0.91) or T1 fat-sat (water only) images (95% CI - 0.24 to 0.18; p = 1.0). CONCLUSION: Diagnostic abdominal MRI can be performed on a prototype 0.55 T scanner, either with conventional or with reduced gradient performance, within an acquisition time of 10 min or less.

Effects of horizontal versus vertical bolster alignment on anatomical orientation of kidney as applied to prone percutaneous nephrolithotomy.

PURPOSE: To evaluate the anatomical changes in kidney orientation in prone position with use of horizontal or vertical bolster alignment. METHODS: Patients having renal stone(s) on ultrasonogram or X-ray underwent split bolus computed-tomo-urography (CTU) in prone position with horizontal and vertical bolster positions. CTUs were read by a single radiologist to quantify the cranio-caudal, antero-posterior, side to side and rotational movements of kidneys as relevant to prone percutaneous nephrolithotomy. RESULTS: 19 adult patients with 38 renal units and mean basal metabolic index of 25.6 kg/m2 underwent CTU. Greater inferior displacement of both kidneys was seen with horizontal bolsters as compared to vertical bolsters. The right upper calyceal-diaphragm distance was 2.1 ± 1.5 cm and the lower calyceal-diaphragm distance was 2.0 ± 1.6 cm greater with the horizontal bolsters (p < 0.01). Similarly, the displacement on the left side was 1.5 ± 0.8 cm and 1.4 ± 0.8 cm, respectively (p < 0.01). Horizontal bolsters also result in significantly longer calyceal-skin distance at both poles of both kidneys [right upper: 0.4 ± 0.5 cm (p < 0.01), right lower: 0.8 ± 0.7 cm (p < 0.01), left upper: 0.4 ± 0.6 cm (p = 0.02), left lower: 0.8 ± 1.1 cm (p < 0.01)] and wider erector spinae-mid posterior calyceal-colon angle (124.8 v/s 110.0 on the right and 96.2 v/s 85.7 on the left) (p < 0.01). CONCLUSION: Horizontal bolsters provide significantly more caudal displacement of the kidneys; the right kidney being displaced more as compared to the left. However, there is also an increase in the skin-calyceal distance with horizontal as compared to the vertical bolsters. These assessments may help the surgeons decide optimal bolster position individualized to the patient.

Unilateral submandibular gland aplasia with contralateral hypertrophy: an unusual neck mass.

The congenital absence of major salivary glands is an infrequent disorder, in which several glands are usually involved at the same time. Aplasia of unilateral submandibular (SM) gland is a very rare finding. Clinical presentation is variable. While some patients have no symptoms, others report difficulty in chewing and swallowing due to dry mouth, and even dental caries. Diagnosis of salivary gland aplasia can be made with a variety of imaging techniques, which include sonography, CT or MRI, sialography or isotope scans (technetium T99m-pertechnetate). We report the case of a 30-year-old man presenting with a gradually progressive neck mass, because of unilateral SM gland hypertrophy associated with contralateral SM gland aplasia.

Clinicoradiologic predictors of sclerotherapy response in low-flow vascular malformations.

OBJECTIVE: To evaluate the clinical effectiveness of sclerotherapy agents in low-flow vascular malformations (LFVM) and identify clinical/imaging features to predict response. METHODS: A retrospective analysis of hospital records of symptomatic LFVM patients who underwent phlebosclerotherapy from January 2015 to April 2018 was done. Patients were subdivided into venous malformations (VM) and lymphatic malformations (LM). Out of 246 cases, 223 patients (132 males, 91 females; age range, 2-52 years) had VM and 23 (13 males, 10 females; age range, 3 months to 45 years) had LM. The clinical response was graded as excellent (>60%), good (30%-60%), and poor (<30%). More than 30% was considered as acceptable response. The χ2 test was performed for correlation between clinical response and clinical, sonographic, magnetic resonance imaging, phlebographic parameters followed by multilinear regression. RESULTS: Cavitary (43%) and spongy (37.7%) were the most common phlebographic patterns seen among VM and a cavitary pattern (87%) was most frequent in LM. Sodium tetradecyl sulphate and bleomycin were most commonly used sclerosants in VM and LM, respectively. The mean number of sessions was 4.35 (range, 1-23) in VM and 2.64 (range, 2-7) in LM. Among VM, 114 patients (51.1%) had excellent response to treatment (>60%) and 75.8% patients had an acceptable response (>30%). All patients with LM had an acceptable response (excellent response in 86.9%). Clinical disfigurement, discoloration, diffuse involvement, dysplastic venous morphology on phlebogram, and late and indirect draining vein correlated with poor response to sclerotherapy in VM (P = .003, P = .036, P = .007, P = .008, P = .003, and P = .035, respectively). Cystic components on ultrasound examination and direct draining vein were seen more often in excellent responders (P = .004 and P = .007) in addition to absence of disfigurement, discoloration, and diffuse involvement (P = .032, P = .003, and P = .002). Mod els comprising clinical disfigurement, dysplastic veins, and late draining vein had the greatest predictive value for poor response (R2 = 0.256). Also, the best model for predicting excellent response comprised presence of direct draining vein and absence of skin discoloration (R2 = 0.109). Eleven instances of minor complications occurred among a total of 1032 sessions, seven with sodium tetradecyl sulphate and four with polidocanol. CONCLUSIONS: Acceptable response to sclerotherapy was achieved in majority of LFVM with extremely low complication rates. Clinicoradiologic features, especially phlebographic findings, correlated with response to sclerotherapy.

Comparison of Magnetic Resonance Imaging and Ultrasonography in Diagnosing and Grading Carpal Tunnel Syndrome: A Prospective Study.

OBJECTIVE: To use anatomic measurements on magnetic resonance imaging (MRI) and ultrasonography (USG) in diagnosing and grading carpal tunnel syndrome (CTS) using nerve conduction studies (NCS) as the gold standard. MATERIAL AND METHODS: In this prospective study, 26 patients with CTS (45 wrists; 22 female and 4 male patients; mean ±â€¯SD age of 49.42 + 14.47 years) and 19 age and sex matched healthy volunteers (32 wrists; 15 female and 4 male volunteers, mean ±â€¯SD age of 42.52 + 10.85 years) underwent MRI and USG. Cross-sectional area (CA) of median nerve was measured using free hand ROI at four levels: hamate hook (H0), pisiform bone (PI0), 1 cm proximal (PI1) and 2 cm proximal to PI0 (PI2). Relative median nerve signal intensity (MNSI) was calculated as ratio of median nerve signal intensity with hypothenar muscle signal intensity. Flexor retinacular bowing was calculated at hamate hook level. Echogenicity and Power Doppler vascularity of median nerve were assessed on USG. Independent t-test, chi square test and receiver operating characteristic curve analysis were used as appropriate. RESULTS: On USG, CA measured at PI0 (95% confidence interval of 0.872-0.987) and retinacular bowing (0.816-0.912), while, on MRI, CA at PI1 (0.874-0.997) were most useful in diagnosing CTS based on the ROC and Zombie plot analysis. Area under curves for CA measurements on USG and MRI were not significantly different. CA at PI1 on MRI (0.752-0.965) was significantly different between minimal to moderate CTS and severe to extreme CTS groups (on NCS). CONCLUSION: CA of median nerve is the most useful parameter to diagnose and grade CTS and USG and MRI are comparable for measurements. Increased retinacular bowing on USG and hypoechogenicity of median nerve increase the diagnostic confidence while MRI helps in picking up important associated conditions.

Traumatic Airway Injuries: Role of Imaging.

Airway Injuries are rare but often immediately life threatening. Incidence ranges from 0.5-2 % in blunt and 1-6 % in penetrating trauma. Upper airway injuries (UAI) are often clinically apparent and get shunted during the primary survey in the emergency department. Few UAI and majority of lower airway injuries (LAI) are occult on primary survey and need a high suspicion index. Clinically, the diagnosis of tracheobronchial injury is delayed in many patients because the airway column is maintained by the peribronchial tissue. Imaging in the form of MDCT, in conjunction with endoscopy, plays a role in delineating the exact site and extent of injury and ruling out associated vascular and esophageal injuries for definitive management of UAI. Chest radiographs and ultrasonography help raise suspicion of LAI by detection of pneumomediastinum, persistent pneumothorax and/or subcutaneous emphysema and should be followed up with multidetector computed tomography (MDCT) which is the mainstay of diagnosis. However, it requires careful evaluation of the airway tract and a thorough knowledge about the mechanism of trauma for detection of subtle injuries. Reconstructions in multiple planes and use of various post-processing techniques including minimum intensity projection (MinIP) images enhance the detection rate. The specific signs of LAI on CT include discontinuity in the tracheobronchial tree, focal intimal flap projecting in the lumen, focal soft tissue attached to the tracheal/bronchial wall, complete cut off of the bronchus/trachea and the fallen lung sign. We, hereby, illustrate the imaging spectrum of traumatic airway injuries in detail and discuss their management implications.

Efficient neutralization of primary isolates by the plasma from HIV-1 infected Indian children.

We tested the plasma of 51 HIV-1-infected children (23 naïve and 28 ART treated) for neutralization against five primary isolates (PIs) generated from adult Indian HIV-1-infected patients. The plasma exhibited neutralization potential with significantly higher neutralizing antibody titers in ART-treated children than naïve children against three out of five PIs (p<0.0001). Further, in treated children, neutralizing antibody titers were higher in those children with suppressed viremia (<1000 RNA copies/mL) than non-suppressors against two of the three PIs. We report here for the first time the neutralization potential of the plasma of HIV-1-infected Indian children.