Incidence and outcomes of incidental breast lesions detected on cross-sectional imaging examinations.

The aim of this study was to determine the frequency and outcomes of incidental breast lesions detected on nonbreast specific cross-sectional imaging examinations. A retrospective review of the medical records was performed to identify all patients without a known history of breast cancer, who had an incidentally discovered breast lesion detected on a nonbreast imaging examination performed at our institution between September 2008 and August 2012 for this IRB-approved, HIPAA compliant study. Outcomes of the incidental lesions were determined by follow-up with dedicated breast imaging (mammography, breast ultrasound, and/or breast MRI) or results of biopsy, if performed. Imaging modality of detection, imaging features, patient age, patient location at the time of the nonbreast imaging examination, type of follow-up, and final outcome were recorded. Rates of malignancy were also calculated, and comparison was made across the different cross-sectional imaging modalities. Kruskal-Wallis and Fisher's exact tests were used to identify factors associated with an increased rate of malignancy. Logistic regression was used to model the risk of malignancy as a function of continuous predictors (such as patient age or lesion size); odds ratios and 95% confidence intervals were obtained. A total of 292 patients with incidental breast lesions were identified, 242 of whom had incidental lesions were noted on computed tomography (CT) studies, 25 on magnetic resonance imaging (MRI), and 25 on positron emission tomography (PET). Although most of the incidental breast lesions were detected on CT examinations, PET studies had the highest rate of detection of incidental breast lesions per number of studies performed (rate of incidental breast lesion detection on PET studies was 0.29%, compared to 0.10% for CT and 0.01% for MRI). Of the 121 of 292 (41%) patients who received dedicated breast imaging work-up at our institution, 40 of 121 (33%) underwent biopsy and 25 of 121 (21%) had malignancy. There was a significantly increased rate of malignancy in older patients (odds ratio: 1.05, 95% CI: 1.02-1.093; P = .006). Additionally, patients with PET-detected incidental breast lesions had a significantly higher rate of malignancy (55%), compared to patients with CT-detected (35%) and MRI-detected (8%) incidental breast lesions (P = .038). The rate of malignancy upon follow-up of incidental breast lesions detected on nonbreast imaging examinations in this retrospective study was 21%, supporting the importance of emphasizing further work-up of all incidentally detected breast lesions with dedicated breast imaging. Additionally, we found that PET examinations had the highest rate of detection of incidental breast lesions and the highest rate of malignancy, which suggests that PET examinations may be more specific for predicting the likelihood of malignancy of incidental breast lesions, compared to CT and MRI.

Combined gadoxetic acid and gadofosveset enhanced liver MRI for detection and characterization of liver metastases.

PURPOSE: To compare gadoxetic acid alone and combined gadoxetic acid/gadofosveset trisodium-enhanced liver MRI for detection of metastases and differentiation of metastases from haemangiomas. METHODS: Ninety-one patients underwent gadoxetic acid-enhanced liver MRI before and after additional injection of gadofosveset. First, two readers retrospectively identified metastases on gadoxetic acid alone enhanced delayed hepatobiliary phase T1-weighted images together with all other MR images (dynamic images, T2-weighted images, diffusion-weighted images). Second, readers assessed additional T1-weighted images obtained after administration of gadofosveset trisodium. For both interpretations, readers rated lesion conspicuity and confidence in differentiating metastases from haemangiomas. Results were compared using alternative free-response receiver-operating characteristic (AFROC) and conventional ROC methods. Histology and follow-up served as reference standard. RESULTS: There were 145 metastases and 16 haemangiomas. Both readers detected more metastases using combined gadoxetic acid/gadofosveset (reader 1 = 130; reader 2 = 124) compared to gadoxetic acid alone (reader 1 = 104; reader 2 = 103). Sensitivity of combined gadoxetic acid/gadofosveset (reader 1 = 90 %; reader 2 = 86 %) was higher than that of gadoxetic acid alone (reader 1 = 72 %; reader 2 = 71 %, both P < 0.01). AFROC-AUC was higher for the combined technique (0.92 vs. 0.86, P < 0.001). Sensitivity for correct differentiation of metastases from haemangiomas was higher for the combined technique (reader 1 = 98 %; reader 2 = 99 % vs. reader 1 = 86 %; reader 2 = 91 %, both P < 0.01). ROC-AUC was significantly higher for the combined technique (reader 1 = 1.00; reader 2 = 1.00 vs. reader 1 = 0.87; reader 2 = 0.92, both P < 0.01). CONCLUSION: Combined gadoxetic acid/gadofosveset-enhanced MRI improves detection and characterization of liver metastases compared to gadoxetic acid alone. KEY POINTS: • Combined gadoxetic acid and gadofosveset-enhanced liver MRI significantly improves detection of metastases. • The combined enhancement technique improves the accuracy to differentiate metastases from haemangiomas. • Prospective studies need to determine the clinical impact of the combined technique.

Serrated Polyps at CT Colonography: Prevalence and Characteristics of the Serrated Polyp Spectrum.

Purpose To report the prevalence and characteristics of serrated polyps identified in a large, average-risk population undergoing screening computed tomographic (CT) colonography. Materials and Methods This HIPAA-compliant retrospective study was approved by the institutional review board of the University of Wisconsin School of Medicine and Public Health. The need for informed consent was waived. Nine thousand six hundred examinations from 8289 patients were enrolled in a single-institution CT colonography-based screening program (from 2004 to 2011) and were evaluated for the presence of nondiminutive serrated lesions and advanced adenomas. The prevalence and characteristics of these lesions were tabulated. Generalized estimating equation regressions of polyp characteristics that may contribute to visualization of serrated lesions were investigated, including polyp size, location, and morphologic appearance; histologic findings; and presence or absence of contrast material tagging. Results Nondiminutive serrated lesions (≥6 mm) were seen at CT colonography-based screening with a prevalence of 3.1% (254 of 8289 patients). Sessile serrated adenomas (SSAs) and traditional serrated adenomas (TSAs) constituted 36.8% (137 of 372) and 4.3% (16 of 372) of serrated lesions, respectively; hyperplastic polyps (HPs) accounted for 58.9% (219 of 372 lesions). SSA and TSA tended to be large (mean size, 10.6 mm and 14.1 mm, respectively), with size categories and polyp subgroups significantly associated (P < .0001). SSA tended to be proximal in location (91.2%, 125 of 137 lesions) and flat in morphologic appearance (39.4%, 54 of 137 lesions) compared with TSA and HP. The presence of high-grade dysplasia in serrated lesions was uncommon when compared with advanced adenomas (one of 372 lesions vs 22 of 395 lesions, respectively; P < .0001). Multivariate analysis showed that contrast material tagging markedly improved serrated polyp detection with an odds ratio of 40.4 (95% confidence interval: 10.1, 161.4). Conclusion Serrated lesions are seen at CT colonography-based screening with a nondiminutive prevalence of 3.1%. These lesions tend to be large, flat, and proximal in location. Adherent contrast material coating on these polyps aids in their detection, despite an often flat morphologic appearance. (©) RSNA, 2016 Online supplemental material is available for this article.

Quantitative magnetic resonance imaging of hepatic steatosis: Validation in ex vivo human livers.

UNLABELLED: Emerging magnetic resonance imaging (MRI) biomarkers of hepatic steatosis have demonstrated tremendous promise for accurate quantification of hepatic triglyceride concentration. These methods quantify the proton density fat-fraction (PDFF), which reflects the concentration of triglycerides in tissue. Previous in vivo studies have compared MRI-PDFF with histologic steatosis grading for assessment of hepatic steatosis. However, the correlation of MRI-PDFF with the underlying hepatic triglyceride content remained unknown. The aim of this ex vivo study was to validate the accuracy of MRI-PDFF as an imaging biomarker of hepatic steatosis. Using ex vivo human livers, we compared MRI-PDFF with magnetic resonance spectroscopy-PDFF (MRS-PDFF), biochemical triglyceride extraction, and histology as three independent reference standards. A secondary aim was to compare the precision of MRI-PDFF relative to biopsy for the quantification of hepatic steatosis. MRI-PDFF was prospectively performed at 1.5 Tesla in 13 explanted human livers. We performed colocalized paired evaluation of liver fat content in all nine Couinaud segments using single-voxel MRS-PDFF (n=117) and tissue wedges for biochemical triglyceride extraction (n=117), and five core biopsies performed in each segment for histologic grading (n=585). Accuracy of MRI-PDFF was assessed through linear regression with MRS-PDFF, triglyceride extraction, and histology. Intraobserver agreement, interobserver agreement, and repeatability of MRI-PDFF and histologic grading were assessed through Bland-Altman analyses. MRI-PDFF showed an excellent correlation with MRS-PDFF (r=0.984, confidence interval 0.978-0.989) and strong correlation with histology (r=0.850, confidence interval 0.791-0.894) and triglyceride extraction (r=0.871, confidence interval 0.818-0.909). Intraobserver agreement, interobserver agreement, and repeatability showed a significantly smaller variance for MRI-PDFF than for histologic steatosis grading (all P<0.001). CONCLUSION: MRI-PDFF is an accurate, precise, and reader-independent noninvasive imaging biomarker of liver triglyceride content, capable of steatosis quantification over the entire liver.

The Liver Segmental Volume Ratio for Noninvasive Detection of Cirrhosis: Comparison With Established Linear and Volumetric Measures.

OBJECTIVE: The aim of this study was to compare the liver segmental volume ratio (LSVR), a novel volumetric computed tomography measurement, with established linear measurements for differentiating normal from cirrhotic livers. METHODS: Hepatic volumes were measured using semiautomated software (Liver Analysis Application, Philips IntelliSpace Portal) on contrast-enhanced abdominal computed tomography scans in 312 adults, including 108 patients with end-stage liver disease (mean age, 55 years; 63 men/45 women) and 204 healthy controls (potential renal donors; mean age, 46 years; 82 men/122 women). The LSVR was defined as the volume ratio of Couinaud segments I to III to segments IV to VIII. Linear measures included the caudate-to-right lobe ratio and maximal splenic dimension. RESULTS: Differences in LSVR between cirrhotics and controls were highly significant (P < 0.0001; mean, 0.55 ± 0.29 versus 0.27 ± 0.07; receiver operating characteristic [ROC] area under the curve [AUC], 0.916). Linear caudate-to-right lobe ratio differences were not statistically significant between the 2 cohorts (P = 0.051; ROC AUC, 0.567). Total liver volume was ineffective for discrimination (ROC AUC, 0.598). An LSVR threshold of 0.35 or greater had a sensitivity and specificity for cirrhosis of 81.5% and 88.7%, respectively. CONCLUSIONS: Regional hepatic volume changes, as reflected by the LSVR, are more effective than standard linear measures or total liver volume for differentiating cirrhotic from normal livers.

Sub-milliSievert (sub-mSv) CT colonography: a prospective comparison of image quality and polyp conspicuity at reduced-dose versus standard-dose imaging.

OBJECTIVE: To prospectively compare reduced-dose (RD) CT colonography (CTC) with standard-dose (SD) imaging using several reconstruction algorithms. METHODS: Following SD supine CTC, 40 patients (mean age, 57.3 years; 17 M/23 F; mean BMI, 27.2) underwent an additional RD supine examination (targeted dose reduction, 70-90%). DLP, CTDI(vol), effective dose, and SSDE were compared. Several reconstruction algorithms were applied to RD series. SD-FBP served as reference standard. Objective image noise, subjective image quality and polyp conspicuity were assessed. RESULTS: Mean CTDI(vol) and effective dose for RD series was 0.89 mGy (median 0.65) and 0.6 mSv (median 0.44), compared with 3.8 mGy (median 3.1) and 2.8 mSv (median 2.3) for SD series, respectively. Mean dose reduction was 78%. Mean image noise was significantly reduced on RD-PICCS (24.3 ± 19HU) and RD-MBIR (19 ± 18HU) compared with RD-FBP (90 ± 33), RD-ASIR (72 ± 27) and SD-FBP (47 ± 14 HU). 2D image quality score was higher with RD-PICCS, RD-MBIR, and SD-FBP (2.7 ± 0.4/2.8 ± 0.4/2.9 ± 0.6) compared with RD-FBP (1.5 ± 0.4) and RD-ASIR (1.8 ± 0.44). A similar trend was seen with 3D image quality scores. Polyp conspicuity scores were similar between SD-FBP/RD-PICCS/RD-MBIR (3.5 ± 0.6/3.2 ± 0.8/3.3 ± 0.6). CONCLUSION: Sub-milliSievert CTC performed with iterative reconstruction techniques demonstrate decreased image quality compared to SD, but improved image quality compared to RD images reconstructed with FBP. KEY POINTS: • CT colonography dose can be substantially lowered using advanced iterative reconstruction techniques. • Iterative reconstruction techniques (MBIR/PICCS) reduce image noise and improve image quality. • The PICCS/MBIR-reconstructed, reduced-dose series shows decreased 2D/3D image quality compared to the standard-dose series. • Polyp conspicuity was similar on standard-dose images compared to reduced-dose images reconstructed with MBIR/PICCS.

Longitudinal Changes in Liver Fat Content in Asymptomatic Adults: Hepatic Attenuation on Unenhanced CT as an Imaging Biomarker for Steatosis.

OBJECTIVE: The objective of this study was to evaluate changes in liver fat content over time in asymptomatic adults and to investigate the factors that may influence these changes. MATERIALS AND METHODS: Liver attenuation on unenhanced CT images of 1022 asymptomatic adults (556 women and 466 men; mean age at the time of the index CT examination, 56.7 years) was retrospectively measured on initial and surveillance CT colonography screening examinations (mean [± SD] interval, 5.5 ± 0.8 years). Changes in liver attenuation (expressed as Hounsfield units) were assessed according to various factors, including body mass index (BMI), age, and sex. RESULTS: Mean liver attenuation was 60.3 HU on the index CT scan and 58.4 HU on the 5-year follow-up CT scan (p < 0.0001). Changes in liver attenuation greater than 10 HU, 5-10 HU, and less than 5 HU were observed in 187 (18%), 212 (21%), and 623 (61%) individuals, respectively. Changes in attenuation greater than 10 HU were negative (i.e., fattier liver) in 130 of 187 individuals (70%) and were more likely to be associated with an increase in BMI (83 of 130 individuals [64%] vs 19 of 57 individuals [33%]; p < 0.0001). For changes in attenuation of 5 HU or more, negative (steatotic) changes outnumbered positive changes, occurring in 258 of 1022 individuals (25%) versus 141 of 1022 individuals (14%) (p < 0.0001). Changes in BMI were negatively correlated with changes in attenuation (p = 0.015). There was no statistically significant correlation between changes in attenuation and either age or sex. An improved lipid profile and the use of a lipid-lowering medication regimen correlated with an interval decrease in liver attenuation. CONCLUSION: Changes in liver attenuation over time, reflecting temporal changes in fat content, were quite variable in this asymptomatic adult population and were only partially explained by the factors examined. These observations may provide early insight into the natural history of incidental hepatic steatosis in asymptomatic adults.

Preoperative Pelvic MRI and Serum Cancer Antigen-125: Selecting Women With Grade 1 Endometrial Cancer for Lymphadenectomy.

OBJECTIVE: The objective of our study was to determine the predictive value of preoperative pelvic MRI and serum cancer antigen-125 (CA-125) evaluation in selecting women with grade 1 endometrial cancer for lymphadenectomy as part of the cancer staging operation. MATERIALS AND METHODS: A new preoperative clinical protocol including MRI and CA-125 evaluation was adopted at our institution in patients with grade 1 endometrioid adenocarcinoma. Lymphadenectomy was considered as part of the surgical staging operation if there was an elevated CA-125 value or a positive MRI finding (≥ 50% myometrial invasion, cervical invasion, abnormal lymph nodes, extrauterine disease, or tumor index ≥ 36 cm). From January 2012 through May 2013, a retrospective analysis was performed of 100 women who underwent preoperative MRI and CA-125 evaluation; we refer to this cohort as the "preoperative study cohort." The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated using final surgical pathology and CA-125 results as the reference standard. The rate of metastatic lymph nodes in the preoperative study cohort was determined. From May 2009 through January 2011, a retrospective analysis of a cohort who did not undergo preoperative MRI and CA-125 evaluation was undertaken to compare lymphadenectomy and lymph node metastasis rates before and after implementation of the new protocol; we refer to this cohort as the "historical cohort." RESULTS: The new clinical protocol had sensitivity of 94%, specificity of 91%, PPV of 84%, and NPV of 97%. When histologic grade alone was considered, positive lymph node rates in the preoperative study cohort was 4.0% versus 4.2% in the historical cohort. In the preoperative study cohort, the lymph node metastasis rate increased to 11.1% with a positive MRI finding or elevated CA-125 value. CONCLUSION: Preoperative MRI and CA-125 evaluation identified women for lymphadenectomy with a high NPV.

Visceral fat quantification in asymptomatic adults using abdominal CT: is it predictive of future cardiac events?

PURPOSE: The purpose of this study was to determine if quantifying visceral adipose tissue (VAT) at CT in asymptomatic adults can predict the likelihood of future cardiac events. METHODS: Subcutaneous and visceral fat volumes were obtained from abdominal CT utilizing a validated semi-automated software tool in 663 asymptomatic adults (mean age 57.3 years, 379F/284M) undergoing colorectal screening. Patients were followed for subsequent cardiac events, defined as myocardial infarction or coronary intervention for a mean follow-up interval of 7.0 ± 1.4 years. Relevant clinical data including Framingham risk score (FRS) were also collected. Statistical analysis included logistic regression, Pearson correlation coefficients, and Welch and Wilcoxon rank sum tests. RESULTS: Cardiac events were documented in 32 subjects (4.8%) an average 3.0 years after index CT. FRS was predictive of future cardiac events, signified by a higher score (mean score 11.9 vs. 7.4; p < 0.001). HDL levels were significantly lower in the cardiac event cohort (mean 52.2 vs. 61.0; p < 0.01). None of the other clinical variables were predictive and none of the CT-based fat measurements (visceral, subcutaneous, and total adipose tissue; visceral fat %) correlated with future cardiac events (p = 0.561­0.886). Mean visceral fat % in the cardiac event cohort was 38.1% vs. 39.1% for the non-event group. CONCLUSION: Quantification of VAT at abdominal CT was not predictive of future cardiac events in this asymptomatic cohort, whereas HDL levels and FRSs correlated well with risk.

Effects of two different anesthetic protocols on cardiac flow measured by two dimensional phase contrast magnetic resonance imaging.

Companion animals are routinely anesthetized or heavily sedated for cardiac MRI studies, however effects of varying anesthetic protocols on cardiac function measurements are incompletely understood. The purpose of this prospective study was to compare effects of two anesthetic protocols (Protocol A: Midazolam, fentanyl; Protocol B: Dexmedetomidine) on quantitative and qualitative blood flow values measured through the aortic, pulmonic, mitral, and tricuspid valves using two-dimensional phase contrast magnetic resonance imaging (2D PC MRI) in healthy dogs. Mean flow per heartbeat values through the pulmonary artery (Qp) and aorta (Qs) were compared to right and left ventricular stroke volumes (RVSV, LVSV) measured using a reference standard of 2D Cine balanced steady-state free precession MRI. Pulmonary to systemic flow ratio (Qp/Qs) was also calculated. Differences in flow and Qp/Qs values generated using 2D PC MRI did not differ between the two anesthetic protocols (P = 1). Mean differences between Qp and RVSV were 3.82 ml/beat (95% limits of agreement: 3.62, -11.26) and 1.9 ml/beat (-7.86, 11.66) for anesthesia protocols A and B, respectively. Mean differences between Qs and LVSV were 1.65 ml/beat (-5.04, 8.34) and 0.03 ml/beat (-4.65, 4.72) for anesthesia protocols A and B, respectively. Mild tricuspid or mitral reflux was seen in 2/10 dogs using 2D PC MRI. No aortic or pulmonic insufficiency was observed. Findings from the current study indicated that these two anesthetic protocols yield similar functional measures of cardiac blood flow using 2D PC MRI in healthy dogs. Future studies in clinically affected patients are needed.

QUANTITATIVE PLANAR AND VOLUMETRIC CARDIAC MEASUREMENTS USING 64 MDCT AND 3T MRI VS. STANDARD 2D AND M-MODE ECHOCARDIOGRAPHY: DOES ANESTHETIC PROTOCOL MATTER?

Cross-sectional imaging of the heart utilizing computed tomography and magnetic resonance imaging (MRI) has been shown to be superior for the evaluation of cardiac morphology and systolic function in humans compared to echocardiography. The purpose of this prospective study was to test the effects of two different anesthetic protocols on cardiac measurements in 10 healthy beagle dogs using 64-multidetector row computed tomographic angiography (64-MDCTA), 3T magnetic resonance (MRI) and standard awake echocardiography. Both anesthetic protocols used propofol for induction and isoflourane for anesthetic maintenance. In addition, protocol A used midazolam/fentanyl and protocol B used dexmedetomedine as premedication and constant rate infusion during the procedure. Significant elevations in systolic and mean blood pressure were present when using protocol B. There was overall good agreement between the variables of cardiac size and systolic function generated from the MDCTA and MRI exams and no significant difference was found when comparing the variables acquired using either anesthetic protocol within each modality. Systolic function variables generated using 64-MDCTA and 3T MRI were only able to predict the left ventricular end diastolic volume as measured during awake echocardiogram when using protocol B and 64-MDCTA. For all other systolic function variables, prediction of awake echocardiographic results was not possible (P = 1). Planar variables acquired using MDCTA or MRI did not allow prediction of the corresponding measurements generated using echocardiography in the awake patients (P = 1). Future studies are needed to validate this approach in a more varied population and clinically affected dogs.

Predicting invasive breast cancer versus DCIS in different age groups.

BACKGROUND: Increasing focus on potentially unnecessary diagnosis and treatment of certain breast cancers prompted our investigation of whether clinical and mammographic features predictive of invasive breast cancer versus ductal carcinoma in situ (DCIS) differ by age. METHODS: We analyzed 1,475 malignant breast biopsies, 1,063 invasive and 412 DCIS, from 35,871 prospectively collected consecutive diagnostic mammograms interpreted at University of California, San Francisco between 1/6/1997 and 6/29/2007. We constructed three logistic regression models to predict the probability of invasive cancer versus DCIS for the following groups: women ≥ 65 (older group), women 50-64 (middle age group), and women < 50 (younger group). We identified significant predictors and measured the performance in all models using area under the receiver operating characteristic curve (AUC). RESULTS: The models for older and the middle age groups performed significantly better than the model for younger group (AUC = 0.848 vs, 0.778; p = 0.049 and AUC = 0.851 vs, 0.778; p = 0.022, respectively). Palpability and principal mammographic finding were significant predictors in distinguishing invasive from DCIS in all age groups. Family history of breast cancer, mass shape and mass margins were significant positive predictors of invasive cancer in the older group whereas calcification distribution was a negative predictor of invasive cancer (i.e. predicted DCIS). In the middle age group--mass margins, and in the younger group--mass size were positive predictors of invasive cancer. CONCLUSIONS: Clinical and mammographic finding features predict invasive breast cancer versus DCIS better in older women than younger women. Specific predictive variables differ based on age.

Rapid multicomponent T2 analysis of the articular cartilage of the human knee joint at 3.0T.

PURPOSE: To determine the feasibility of using multicomponent-driven equilibrium single-shot observation of T1 and T2 (mcDESPOT) for evaluating the human knee joint at 3.0T and to investigate depth-dependent and regional-dependent variations in multicomponent T2 parameters within articular cartilage. MATERIALS AND METHODS: mcDESPOT was performed on the knee joint of 10 asymptomatic volunteers at 3.0T. Single-component T2 relaxation time (T2single ), multicomponent T2 relaxation time for water tightly bound to proteoglycan (T2PG ) and bulk water loosely bound to the macromolecular matrix (T2BW ), and fraction of water tightly bound to proteoglycan (FPG ) were measured in eight cartilage subsections and within the superficial and deep layers of patellar cartilage. Statistical analysis was used to investigate depth-dependent and regional-dependent variations in parameters. RESULTS: There was lower (P = 0.001) T2single and T2PG and higher (P < 0.001) FPG in the deep than superficial layer of patellar cartilage. There was higher (P < 0.001) FPG on the weight-bearing surfaces than nonweight-bearing surfaces. There was higher (P < 0.001) T2single , T2PG , and T2BW on the trochlea and posterior medial and lateral femoral condyles than the patella, central medial and lateral femoral condyles, and medial and lateral tibia plateaus. CONCLUSION: Multicomponent T2 parameters of the articular cartilage of the human knee joint can be measured at 3.0T using mcDESPOT and show depth-dependent and regional-dependent variations.

Hyperpolarized Helium-3 MRI of exercise-induced bronchoconstriction during challenge and therapy.

PURPOSE: To investigate the utility of hyperpolarized He-3 MRI for detecting regional lung ventilated volume (VV) changes in response to exercise challenge and leukotriene inhibitor montelukast, human subjects with exercise induced bronchoconstriction (EIB) were recruited. This condition is described by airway constriction following exercise leading to reduced forced expiratory volume in 1 second (FEV1) coinciding with ventilation defects on hyperpolarized He-3 MRI. MATERIALS AND METHODS: Thirteen EIB subjects underwent spirometry and He-3 MRI at baseline, postexercise, and postrecovery at multiple visits. On one visit montelukast was given and on two visits placebo was given. Regional VV was calculated in the apical/basilar dimension, in the anterior/posterior dimension, and for the entire lung volume. The whole lung VV was used as an end-point and compared with spirometry. RESULTS: Postchallenge FEV1 dropped with placebo but not with treatment, while postchallenge VV dropped more with placebo than treatment. Sources of variability for VV included region (anterior/posterior), scan, and treatment. VV correlated with FEV1/ forced vital capacity (FVC) and forced expiratory flow between 25 and 75% of FVC and showed gravitational dependence after exercise challenge. CONCLUSION: A paradigm testing the response of ventilation to montelukast revealed both a whole-lung and regional response to exercise challenge and therapy in EIB subjects.

Contrast coating for the surface of flat polyps at CT colonography: a marker for detection.

OBJECTIVES: To assess the frequency of oral contrast coating of flat polyps, which may promote detection, and influencing factors within a screening CT colonography (CTC) population. METHODS: This was a retrospective, observational study performed at one institution. From 7,426 individuals, 123 patients with 160 flat polyps were extracted. Flat polyps were defined as plaque-like, raised at most 3 mm in height and reviewed for contrast coating. Factors including demographic variables such as age and sex, and polyp variables such as polyp size, location and histology were analysed for effect on coating. RESULTS: Of 160 flat polyps (mean size 9.4 mm ± 3.6), 78.8 % demonstrated coating. Mean coat thickness was 1.5 mm ± 0.6; 23.8 % (n = 30) demonstrated a thin film of contrast. Large size (≥10 mm) and proximal colonic location (relative to splenic flexure) were predictive variables by univariate logistic regression [OR (odds ratio) 3.4 (CI 1.3-8.9; p = 0.011), 2.0 (CI 1.2-3.5; p = 0.011), respectively]. Adenomas (OR 0.37, CI 0.14-1.02; p = 0.054) and mucosal polyps or venous blebs (OR 0.07, CI 0.02-0.25; p < 0.001) were less likely to coat than serrated/hyperplastic lesions. Age and sex were not predictive for coating (p = 0.417, p = 0.499, respectively). CONCLUSIONS: Surface contrast coating is common for flat polyps at CTC, promoted by large size, proximal location and serrated/hyperplastic histology. Given the difficulty in detection, recognition may aid in flat polyp identification. KEY POINTS: • Oral contrast coats the surface of most flat colorectal polyps at CT colonography. • Large size, proximal colonic location and serrated/hyperplastic histology increase polyp coating. • Contrast coating increases diagnostic confidence for flat polyps. • Contrast coating may help in flat polyp detection at CTC.

Natural history of hepatic steatosis: observed outcomes for subsequent liver and cardiovascular complications.

OBJECTIVE: Hepatic steatosis is a common incidental finding at radiologic imaging. The natural history of nonalcoholic fatty liver disease (NAFLD) and its associated risks for cardiovascular complications are not well established in this context. Our purpose was to investigate the clinical outcome of moderate-to-severe hepatic steatosis detected incidentally at CT. MATERIALS AND METHODS: Liver attenuation was measured at unenhanced CT in 4412 consecutive adults scanned over a 12-month period. Moderate-to-severe steatosis was diagnosed by liver attenuation less than or equal to 45 HU, which is essentially 100% specific for histologic grading of 30% or more fat content. The control group was defined by a high-normal liver attenuation of 60-65 HU. The main exclusion criteria were preexisting liver disease (beyond asymptomatic NAFLD), alcoholism, or less than 1 year of clinical follow-up. A medical record review assessed for the development of symptomatic liver disease (including nonalcoholic steatohepatitis and cirrhosis) and seminal cardiovascular events (myocardial infarction, cerebrovascular accident, transient ischemic attacks, or coronary bypass or stent). Data for body mass index, diabetes, and liver enzyme levels were also recorded. RESULTS: Five hundred three adults (11.4%) had unenhanced CT liver attenuation of 45 HU or less, yielding a final steatosis cohort of 282 patients after exclusions; the control group consisted of 768 patients after exclusions. The mean (± SD) patient age (51.4 ± 14.7 vs 50.8 ± 17.4 years), sex (53.9% vs 54.7% female), and mean follow-up intervals (7.3 ± 3.2 vs 7.7 ± 3.2 years) were similar between groups. No patient in either group had progression of liver disease beyond incidental steatosis. Subsequent cardiovascular events were more common in the steatosis cohort (9.9% vs 5.9%; p = 0.028), but steatosis was not an independent risk factor after controlling for diabetes and body mass index in multiple logistic regression analysis. CONCLUSION: This longitudinal study failed to show progression of moderate-to-severe hepatic steatosis to symptomatic forms of fatty liver disease over a 5- to 10-year time horizon. Aggressive workup of hepatic steatosis found incidentally on imaging does not appear to be warranted. Steatosis was a biomarker for subsequent cardiovascular events but not an independent risk factor.

MRI characteristics of healed and unhealed peripheral vertical meniscal tears.

OBJECTIVE: The objective of our study was to retrospectively compare the MRI characteristics of surgically confirmed healed and unhealed peripheral vertical meniscal tears. MATERIALS AND METHODS: The study group consisted of 64 patients with 86 peripheral vertical meniscal tears diagnosed on MRI who subsequently underwent knee surgery. The MRI examinations were retrospectively reviewed to assess the following tear characteristics: tear location relative to the meniscocapsular junction, tear width, tear length, tear extension through one or both surfaces, sequences on which tear was visualized, signal intensity of tear on T2-weighted imaging, and presence of low-signal-intensity strands bridging the tear on T2-weighted imaging. Multivariate logistic regression models were used to determine whether MRI characteristics could be used to distinguish between healed and unhealed tears at surgery. RESULTS: Tear location was the most significant characteristic (p<0.001) for distinguishing between healed and unhealed tears: 17 of 18 (94.4%) tears located at the meniscocapsular junction of the medial meniscus were healed and 15 of 68 (22.1%) tears not located at the meniscocapsular junction were healed. For tears not located at the meniscocapsular junction, MRI characteristics significantly associated with healed tears included a tear width of less than 2 mm (p=0.01), tear visualized only on intermediate-weighted imaging (p=0.01), tear showing intermediate or bright signal intensity on T2-weighted imaging (p=0.06), and low-signal-intensity strands bridging the tear on T2-weighted imaging (p<0.001). CONCLUSION: Most peripheral vertical tears at the meniscocapsular junction of the medial meniscus spontaneously heal. The MRI characteristics of tears not located at the meniscocapsular junction can help distinguish between healed and unhealed tears.

Evaluation of the articular cartilage of the knee joint: value of adding a T2 mapping sequence to a routine MR imaging protocol.

PURPOSE: To determine whether the addition of a T2 mapping sequence to a routine magnetic resonance (MR) imaging protocol could improve diagnostic performance in the detection of surgically confirmed cartilage lesions within the knee joint at 3.0 T. MATERIALS AND METHODS: This prospective study was approved by the institutional review board, and the requirement to obtain informed consent was waived. The study group consisted of 150 patients (76 male and 74 female patients with an average age of 41.2 and 41.5 years, respectively) who underwent MR imaging and arthroscopy of the knee joint. MR imaging was performed at 3.0 T by using a routine protocol with the addition of a sagittal T2 mapping sequence. Images from all MR examinations were reviewed in consensus by two radiologists before surgery to determine the presence or absence of cartilage lesions on each articular surface, first by using the routine MR protocol alone and then by using the routine MR protocol with T2 maps. Each articular surface was then evaluated at arthroscopy. Generalized estimating equation models were used to compare the sensitivity and specificity of the routine MR imaging protocol with and without T2 maps in the detection of surgically confirmed cartilage lesions. RESULTS: The sensitivity and specificity in the detection of 351 cartilage lesions were 74.6% and 97.8%, respectively, for the routine MR protocol alone and 88.9% and 93.1% for the routine MR protocol with T2 maps. Differences in sensitivity and specificity were statistically significant (P < .001). The addition of T2 maps to the routine MR imaging protocol significantly improved the sensitivity in the detection of 24 areas of cartilage softening (from 4.2% to 62%, P < .001), 41 areas of cartilage fibrillation (from 20% to 66%, P < .001), and 96 superficial partial-thickness cartilage defects (from 71% to 88%, P = .004). CONCLUSION: The addition of a T2 mapping sequence to a routine MR protocol at 3.0 T improved sensitivity in the detection of cartilage lesions within the knee joint from 74.6% to 88.9%, with only a small reduction in specificity. The greatest improvement in sensitivity with use of the T2 maps was in the identification of early cartilage degeneration.

Aortic pulse wave velocity measurements with undersampled 4D flow-sensitive MRI: comparison with 2D and algorithm determination.

PURPOSE: To compare pulse wave velocity (PWV) measurements obtained from radially undersampled 4D phase-contrast magnetic resonance imaging (PC-MRI) with 2D PC measurements and to evaluate four PWV algorithms. MATERIALS AND METHODS: PWV was computed from radially undersampled 3D, 3-directionally velocity-encoded PC-MRI (4D) acquisitions performed on a 3T MR scanner in 18 volunteers. High temporal resolution 2D PC scans serving as a reference standard were available in 14 volunteers. Four PWV algorithms were tested: time-to-upstroke (TTU), time-to-peak (TTP), time-to-foot (TTF), and cross-correlation (XCorr). Bland-Altman analysis was used to determine inter- and intraobserver reproducibility and to compare differences between algorithms. Differences in age and PWV measurements were analyzed with Student's t-tests. The variability of age-corrected data was assessed with a Brown-Forsythe analysis of variance (ANOVA) test. RESULTS: 2D (4.6-5.3 m/s) and 4D (3.8-4.8 m/s) PWV results were in agreement with previously reported values in healthy subjects. Of the four PWV algorithms, the TTU, TTF, and XCorr algorithms gave similar and reliable results. Average biases of +0.30 m/s and -0.01 m/s were determined for intra- and interobserver variability, respectively. The Brown-Forsythe test revealed that no differences in variability could be found between 2D and 4D PWV measurements. CONCLUSION: 4D PC-MRI with radial undersampling provides reliable and reproducible measurements of PWV. TTU, TTF, and XCorr were the preferred PWV algorithms.

Appendiceal length as an independent risk factor for acute appendicitis.

OBJECTIVES: To determine if appendiceal lengths differ between adults with acute appendicitis and asymptomatic controls. METHODS: In vivo appendiceal length at computed tomography (CT) in 321 adults with surgically proven appendicitis was compared with that in 321 consecutive asymptomatic adult controls. CT length was derived using curved multiplanar reformats along the long axis. Gross pathological length provided external validation for appendectomy cases. RESULTS: Appendiceal length at CT correlated well with appendicitis specimens (mean length, 6.8 cm vs 6.6 cm; 79 % within 1.5 cm). For asymptomatic controls, mean CT appendiceal length was 7.9 cm, longer in men (8.4 ± 3.8 vs 7.4 ± 3.1 cm; P = 0.02), matching closely historical normative post-mortem data. The mean and standard deviation of appendiceal length at CT were significantly greater among negative controls than in the positive appendicitis group (7.9 ± 3.5 vs 6.8 ± 1.9 cm; P = 0.03). Of appendicitis cases, 90 % (288/321) fell within the range 4.0-10.0 cm, compared with 59 % (189/321) of negative controls (P < 0.001). Among controls, a fivefold increase in appendixes >10 cm and a twofold increase in appendixes <4 cm were observed. Half (9/18) of long appendicitis cases showed tip appendicitis at CT. CONCLUSIONS: "Intermediate" appendiceal lengths (4-10 cm) are more frequently complicated by acute appendicitis, whereas both "long" (>10 cm) and "short" (<4 cm) lengths are more frequently observed in unaffected adults.