Improved Reader Confidence Research Articles

Diagnostic performance of short noncontrast biparametric 3-T MRI for tonsillar infections: comparison with a full protocol including contrast-enhanced sequences

BackgroundWe investigated whether a short, 5-min magnetic resonance imaging (MRI) protocol consisting of only axial T2-weighted and diffusion-weighted imaging (DWI) sequences can discriminate between tonsillar infections, peritonsillar abscesses and deeply extending abscesses in a retrospective, blinded, multireader setting.MethodsWe included patients sent by emergency physicians with suspected pharyngotonsillar infections who underwent emergency neck 3-T MRI from April 1 2013 to December 31 2018. Three radiologists (with 10−16 years of experience) reviewed the images for abscesses and their extension into deep neck spaces. Data were reviewed first using only axial T2-weighted Dixon images and DWI (short protocol) and second including other sequences and contrast-enhanced T1-weighted Dixon images (full protocol). Diagnostic accuracy, interobserver agreement, and reader confidence were measured. Surgical findings and clinical course served as standard of reference.ResultsThe final sample consisted of 52 patients: 13 acute tonsillitis with no abscesses, 19 peritonsillar abscesses, and 20 deeply extending abscesses. Using the short protocol, diagnostic accuracy for abscesses across all readers was good-to-excellent: sensitivity 0.93 (95% confidence interval 0.87−0.97), specificity 0.85 (0.70−0.93), accuracy 0.91 (0.85−0.95). Using the full protocol, respective values were 0.98 (0.93−1.00), 0.85 (0.70−0.93), and 0.95 (0.90−0.97), not significantly different compared with the short protocol. Similar trends were seen with detecting deep extension. Interobserver agreement was similar between protocols. However, readers had higher confidence in diagnosing abscesses using the full protocol.ConclusionsShort MRI protocol showed good-to-excellent accuracy for tonsillar abscesses. Contrast-enhanced images improved reader confidence but did not affect diagnostic accuracy or interobserver agreement.Relevance statementShort protocol consisting only of T2-weighted Dixon and DWI sequences can accurately image tonsillar abscesses, which may improve feasibility of emergency neck MRI.Key points• The short 3-T MRI protocol (T2-weighted images and DWI) was faster (5 min) than the full protocol including T1-weighted contrast-enhanced images (24 min).• The short 3-T MRI protocol showed good diagnostic accuracy for pharyngotonsillar abscesses.• Contrast-enhanced sequences improved reader confidence but did not impact diagnostic accuracy or interobserver agreement.Graphical

Dual-energy CT of acute bowel ischemia.

Acute bowel ischemia is a condition with high mortality and requires rapid intervention to avoid catastrophic outcomes. Swift and accurate imaging diagnosis is essential because clinical findings are commonly nonspecific. Conventional contrast enhanced CT of the abdomen has been the imaging modality of choice to evaluate suspected acute bowel ischemia. However, subtlety of image findings and lack of non-contrast or arterial phase images can make correct diagnosis challenging. Dual-energy CT provides valuable information toward assessing bowel ischemia. Dual-energy CT exploits the differential X-ray attenuation at two different photon energy levels to characterize the composition of tissues and reveal the presence or absence of faint intravenous iodinated contrast to improve reader confidence in detecting subtle bowel wall enhancement. With the same underlying technique, virtual non-contrast images can help to show non-enhancing hyperdense hemorrhage of the bowel wall in intravenous contrast-enhanced scans without the need to acquire actual non-contrast scans. Dual-energy CT derived low photon energy (keV) virtual monoenergetic images emphasize iodine contrast and provide CT angiography-like images from portal venous phase scans to better evaluate abdominal arterial patency. In Summary, dual-energy CT aids diagnosing acute bowel ischemia in multiple ways, including improving visualization of the bowel wall and mesenteric vasculature, revealing intramural hemorrhage in contrast enhanced scans, or possibly reducing intravenous contrast dose.

Automated CT registration tool improves sensitivity to change in ventricular volume in patients with shunts and drains.

CT is the mainstay imaging modality for assessing change in ventricular volume in patients with ventricular shunts or external ventricular drains (EVDs). We evaluated the performance of a novel fully automated CT registration and subtraction method to improve reader accuracy and confidence compared with standard CT. In a retrospective evaluation of 49 ventricular shunt or EVD patients who underwent sequential head CT scans with an automated CT registration tool (CT CoPilot), three readers were assessed on their ability to discern change in ventricular volume between scans using standard axial CT images versus reformats and subtraction images generated by the registration tool. The inter-rater reliability among the readers was calculated using an intraclass correlation coefficient (ICC). Bland-Altman tests were performed to determine reader performance compared to semi-quantitative assessment using the bifrontal horn and third ventricular width. McNemar's test was used to determine whether the use of the registration tool increased the reader's level of confidence. Inter-rater reliability was higher when using the output of the registration tool (single measure ICC of 0.909 with versus 0.755 without the tool). Agreement between the readers' assessment of ventricular volume change and the semi-quantitative assessment improved with the registration tool (limits of agreement 4.1 vs 4.3). Furthermore, the tool improved reader confidence in determining increased or decreased ventricular volume (p < 0.001). Automated CT registration and subtraction improves the reader's ability to detect change in ventricular volume between sequential scans in patients with ventricular shunts or EVDs. Our automated CT registration and subtraction method may serve as a promising generalizable tool for accurate assessment of change in ventricular volume, which can significantly affect clinical management.

Stress Echocardiography: An Update

Stress echocardiography (SE) is an established technique for the assessment of extent and severity of coronary artery disease. The combination of echocardiography with a physical, pharmacological or electrical stress allows to detect myocardial ischemia with an excellent accuracy. A transient worsening of regional function during stress is the hallmark of inducible ischemia. In recent years, SE has become an established method for the assessment of a wide spectrum of challenging clinical conditions, including systolic or diastolic heart failure, non-ischaemic cardiomyopathy, valvular heart disease, pulmonary hypertension (PH), athletes’ hearts, congenital heart disease (CHD) and heart transplantation. Advantages of SE include the ubiquitous availability of echocardiography, lack of ionising radiation, choice of physiological or pharmacological stressors, good diagnostic accuracy and robust supporting evidence base. SE has evolved significantly as a technique over the past three decades and has benefitted considerably from improvements in overall image quality (superior resolution), machine technology (e.g. digital cine-loop acquisition and side-by-side image display) and development of second-generation ultrasound contrast agents that have improved reader confidence and diagnostic accuracy. SE provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging or magnetic resonance, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. A paradigm shift will occur when from a highly expertise qualitative reading SE will move to a quantitative approach that would make it easier also for less skilled readers. Technological premises are there at hand but they have not reached a full-blown status to be used on a routine clinical basis. Society recommendations and guidelines are mostly based on consensus and level of evidence C. The gap of knowledge should be filled with prospective large scale studies to support evidence-based treatment strategies. The purpose of this article is to review the breadth of SE in contemporary clinical cardiology.University Heart Journal Vol. 14, No. 1, Jan 2018; 31-37

Transient uterine contractions as a potential pathology mimic on premenopausal pelvic MRI and the role of routine repeat T2 sagittal images to improve observer confidence.

Pelvic MRI has an increasingly important role in the evaluation of non-malignant uterine pathology including uterine leiomyomas, adenomyosis and endometriosis. Normal physiological myometrial junctional zone transient contractions can also be identified on MRI and have the potential to act as pathology mimics. This study aims to evaluate both the incidence of visible physiological contractions in premenopausal female pelvic MRI and also to support the routine acquisition of a repeat T2 sagittal sequence to differentiate transient physiological contractions from true underlying pathology and therefore improve observer confidence. A total of 279 female patients of child-bearing age who had undergone a pelvic MRI over a 16month period met the inclusion criteria. All patients underwent a standard examination protocol on the same hardware. This included performing two separate T2-weighted sagittal sequences as part of the protocol firstly as the initial and then as the final series for the examination. The sagittal series were reviewed separately by four readers and conclusions made for each case with regards to the presence of identifiable contractions on one or both series and their potential to act as pathology mimics. Of the 279 cases, there were 34 cases (12.2%) that were found to have transient junctional zone contractions acting as pathology mimics, resembling either leiomyomata or adenomyosis. Standard MRI sequences need to be able to distinguish normal transient physiological uterine contractions from true pathology to avoid diagnostic error. The routine utility of a repeat T2-weighted sagittal sequence performed at the conclusion of a patient's examination was shown to improve reader confidence in distinguishing transient contractions from true uterine pathology while adding minimal time penalty to the overall examination. It is therefore advocated that all premenopausal female pelvic MRI cases have a T2 sagittal series as the initial and then the final series as part of a routine protocol.

Role of rapid kV-switching dual-energy CT in assessment of post-surgical local recurrence of pancreatic adenocarcinoma.

The purpose of this study is to evaluate the performance of material-specific iodine (MS-I) images generated by rapid kV-switching single-source dual-energy computed tomography (rsDECT) for distinguishing post-operative changes from local tumor recurrence in patients on follow-up for pancreatic adenocarcinoma after surgical resection. In this IRB-approved HIPPA-compliant study, retrospective review of 51 patients who underwent surgical resection of pancreatic adenocarcinoma was conducted and were followed up using contrast-enhanced rsDECT (Discovery CT 750HD, GE Healthcare, Milwaukee, WI). Independent qualitative assessment for presence of local tumor recurrence was performed by two radiologists who evaluated 65keV (single-energy CT-equivalent interpretation) and 65keV with MS-I (rsDECT interpretation) in separate sessions. Quantitative analysis of Hounsfield unit (HU, on 65 keV) and normalized iodine concentration (NIC on MS-I images; iodine concentration ratio in post-operative tissue to aorta) was measured. Follow-up imaging, temporal change of CEA and CA 19-9 or biopsy served as reference standard for presence and absence of local recurrence. Sensitivity and specificity of readers and quantitative parameters was calculated and receiver operating characteristic curves and Fisher's exact test were generated. A p value<0.05 was considered statistically significant. A total of 51 patients (27 females, 24 males) with mean age of 64years built the final cohort. Local recurrence was absent in 23 (Group A) and present in 28 (Group B) patients. The follow-up imaging was performed within 7months of rsDECT. For both readers, the addition of MS-I increased the specificity for tissue characterization and improved reader confidence as compared to 65keV (specificity: 80% and 56%, respectively) images alone. Quantitative analysis revealed a significantly lower NIC (0.28 vs. 0.35; p<0.05) for non-recurrent tissue. However, HU was not significantly different for non-recurrent and recurrent tissue (0.63 vs. 0.70; p>0.05). In inherently complex cases of post-operative pancreatic adenocarcinoma, MS-I images from rsDECT can be a useful adjunct to conventional scans in characterizing loco-regional soft tissue.

COMPARISON OF TRANSVERSE COMPUTED TOMOGRAPHIC EXCRETORY UROGRAPHY IMAGES AND MAXIMUM INTENSITY PROJECTION IMAGES FOR DIAGNOSING ECTOPIC URETERS IN DOGS.

Computed tomographic maximum intensity projection (MIP) images have been shown to improve reader confidence in their diagnoses and to improve detection of vascular structures and pulmonary nodules. The objectives of this method comparison study were to compare transverse source computed tomographic excretory urography (CTEU) images to two, five, and 10 slab thick MIP images for diagnosing canine ectopic ureters, compare reader confidence, and evaluate interobserver agreement. Two board-certified veterinary radiologists and a board-certified small animal internist blindly reviewed transverse source CTEU and two, five, and 10 slab thick MIP images of 24 dogs enrolled in the study. Inclusion criteria included a diagnostic CTEU and either cystoscopic or surgical confirmation of the presence or absence of ureteral ectopia. Eleven dogs were confirmed to have 17 ectopic ureters at surgery and/or cystoscopically. There was no significant difference in reader diagnoses between viewing methods or between viewing methods and the surgical/cystoscopic findings (P < 0.001). Reader confidence was significantly greater on two (P = 0.0080) and five (P = 0.0009) slab thick MIP images with significant interobserver agreement between readers for all viewing methods (P values ranging between 0.0363 and <0.001). In addition, the diagnostic accuracy of MIP images was similar to or better than transverse source CTEU images, when assessed by a radiologist. The study results suggest that CTEU is a reliable imaging technique for diagnosing canine ectopic ureters among specialists of varied experience. In addition, thin slice reconstructed MIP images improve reader confidence and potentially diagnostic accuracy, and thus their use should be considered, especially in more challenging cases.

Application of a Parametric Display of Two-Dimensional Speckle-Tracking Longitudinal Strain to Improve the Etiologic Diagnosis of Mild to Moderate Left Ventricular Hypertrophy

The distinction of hypertrophic cardiomyopathy (HCM) or cardiac amyloidosis (CA) from hypertensive heart disease may be difficult. The aim of this study was to determine the impact of parametric (polar) maps of regional longitudinal strain on identification of the etiology of mild to moderate left ventricular hypertrophy (LVH). Twenty-four consecutive echocardiographic studies with mild to moderate LVH (eight with CA, eight with HCM, and eight with hypertensive heart disease) were selected on the basis of the availability of adequate images to assess longitudinal strain and absence of electrocardiographic criteria for low voltage or LVH or a pseudoinfarct pattern. Twenty level 3-trained readers provided the most likely of three diagnoses (CA, HCM, or hypertensive heart disease) and scored their confidence in making the diagnosis from two-dimensional images and diastolic parameters. A teaching exercise was provided on the interpretation of longitudinal strain in these cohorts, and interpretation was repeated with the addition of the strain polar map. Baseline concordance among the readers was poor (κ = 0.28) and improved with the addition of strain data (κ = 0.57). Accuracy was improved with the addition of polar maps for the entire study cohort (P < .001), with 22% of cases reclassified correctly. The largest improvements in sensitivity (from 40% to 86%, P < .001), specificity (from 84% to 95%, P < .001), and accuracy (from 70% to 92%, P < .001) were seen for CA. The strain polar map significantly improved reader confidence in making the correct diagnosis overall (P < .001). Regional variations in strain are easily recognizable, accurate, and reproducible means of differentiating causes of LVH. The detection of LVH etiology may be a useful clinical application for strain.

JOURNAL CLUB: MRI Assessment of Biliary Ductal Obstruction: Is There Added Value of T1-Weighted Gadolinium-Ethoxybenzyl-Diethylenetriamine Pentaacetic Acid–Enhanced MR Cholangiography?

The goal of the present study was to determine the added value of gadolium-ethoxybenzyl-diethylenetriamine pentaacetic acid (gadoxetate disodium)-enhanced magnetic resonance cholangiography (MRC) to standard liver MRI including T2-weighted MRCP in assessment of biliary ductal obstruction. Thirty-eight patients (mean age, 48.1 ± 16.7 years) (40 total examinations) who underwent liver MRI (including T2-weighted MRCP and gadoxetate disodium-enhanced MRC) for suspicion of biliary disease were included in this institutional review board-approved, HIPAA-compliant retrospective study. Three blinded radiologists first evaluated MR images without gadoxetate disodium-enhanced MRC for presence and significance of biliary obstruction, underlying cause for obstruction, and confidence in final diagnosis. After inclusion of gadoxetate disodium-enhanced MRC, readers again determined presence and significance of biliary obstruction and confidence in final diagnosis. Reference standard was established using MRI along with ERCP, percutaneous transhepatic cholangiography, intraoperative cholangiography, or a combination thereof. Overall sensitivity across all readers in diagnosing significance of obstruction was 60% without gadoxetate disodium-enhanced MRC and 91% with gadoxetate disodium- enhanced MRC (p < 0.001). Across all readers, assessment of significance of obstruction was changed when adding gadoxetate disodium-enhanced MRC in 40 of 120 cases (33%); significance of obstruction was correctly changed in 35 of 40 cases (87.5%). Biliary obstruction was graded of unknown significance in 27 of 120 cases (22.5%) across all readers when gadoxetate disodium-enhanced MRC was not reviewed. Significance of biliary obstruction was classified correctly after adding gadoxetate disodium-enhanced MRC in 25 of these 27 cases (93%). Confidence in final diagnosis was significantly higher with addition of gadoxetate di-sodium-enhanced MRC for two of three readers (p < 0.003). Addition of gadoxetate disodium-enhanced MRC to liver MRI significantly improves sensitivity in assessing significance of biliary obstruction and can improve reader confidence in establishing a final diagnosis. This added information could have a substantial impact in the determination of the most appropriate therapeutic options.

Following unenhanced MRI assessment for local recurrence after surgical resection of mesenchymal soft tissue tumors, do additional gadolinium-enhanced images change reader confidence or diagnosis?

PurposeEvaluate if gadolinium enhanced MR imaging (GeMRI) improves confidence, changes the final diagnosis, or improves accuracy in the assessment of musculoskeletal (MSK) tumor residual or recurrence following surgical resection. We also assess if different experience levels change the above results. Methods and materialsInitially, pre-contrast images were independently reviewed by two radiologists, one with 25 years of experience (R1) and one undergoing MSK specialty training (R2). Two questions were answered: (1) Mass present? and (2) Likelihood of malignancy? Subsequently, both pre-contrast and post-contrast images were independently reviewed. The same questions were again answered plus four others including if GeMRI changed mass characterization, better defined cystic versus solid, better defined tumor extent, or improved conspicuity. Lastly, the readers answered whether GeMRI changed confidence, and changed their final diagnosis. Histologic diagnoses were available in 43 cases, with the remaining 44 cases based upon clinical and/or imaging follow-up. ResultsGeMRI definitely improved confidence in 8/7 cases, and slightly improved confidence in 20/29 cases and changed the final diagnosis in 11/8 cases for R1 and R2 respectively. Positive and negative predictive values statistically improved for R2 (positive predictive value 36.4% versus 50%, p=0.02; negative predictive value 75.4% versus 79.1%, p=0.04) but not for R1. Reader concordance for malignancy improved with GeMRI (κ=0.44 pre-contrast and κ=0.71 post-contrast). ConclusionGeMRI improved reader confidence, improved reader concordance and modestly improved accuracy for the less experienced reader. Where possible, GeMRI should be used in the assessment of MSK tumor residual or recurrence.

Qualitative Assessment of Enhancement in a Renal Mass

To evaluate the impact of subtraction CT on reader confidence and diagnostic accuracy when characterizing renal masses. In this institutional review board-approved retrospective study, 159 patients (85 men and 74 women; mean age, 62.6 years; range, 22-88 years) underwent routine unenhanced and contrast-enhanced multidetector computed tomography (MDCT) for renal lesion characterization. Subtraction images were subsequently generated on scanner console. Two readers independently reviewed the MDCT images to characterize presence of enhancement using a 6-point scale during 3 blinded review sessions of (1) only subtraction, (2) routine, and (3) combined subtraction and routine images. The standard of reference consisted of either histopathology or follow-up imaging and clinical data. Of the 240 lesions evaluated, 60 lesions (mean, 3.2 cm; range, 1-7.5 cm) were enhancing and 180 lesions (mean, 2.7 cm; range, 0.5-12 cm) were nonenhancing. For determination of lesion enhancement, a combined evaluation of routine MDCT and subtraction images improved reader confidence in 60% to 63% of lesions (P < 0.001). The combined evaluation also provided the highest sensitivity (97%), specificity (99%), and accuracy (98.9%). When used in combination with routine image interpretation, subtraction CT improves reader confidence and diagnostic accuracy in identifying enhancement in renal lesions.

Influence of body habitus and use of oral contrast on reader confidence in patients with suspected acute appendicitis using 64 MDCT

The purpose of this study is to evaluate how body habitus affects reader confidence in diagnosing acute appendicitis and appendiceal visualization using 64 MDCT technology with and without oral contrast. We conducted a HIPAA compliant, IRB approved study of adult patients presenting to the Emergency Department with nontraumatic abdominal pain. Subjects were randomized to two groups: 64 MDCT scans performed with oral and intravenous contrast or scans performed solely with intravenous contrast. Three radiologists established their confidence about the presence of appendicitis as well as recording whether the appendix was visualized. Reader confidence in diagnosing acute appendicitis was compared between the two groups for the three readers. The impact of patient BMI and estimated intra-abdominal fat on reader confidence in diagnosing appendicitis was determined. Finally, a comparison of the effect of BMI and intra-abdominal fat on appendiceal visualization between the two groups was carried out. Three hundred three patients were enrolled in this study. There was a statistically significant difference in confidence based on BMI for reader 2, group 1 in diagnosing appendicitis. No further statistically significant differences in reader confidence for diagnosing appendicitis based on BMI or intra-abdominal fat were identified. There was no influence of BMI or intra-abdominal fat on appendiceal visualization. Increasing BMI was seen to improve reader confidence for one of three readers in patients that received both oral and intravenous contrast. No further effects of BMI or intra-abdominal fat on confidence in diagnosing or excluding appendicitis were seen. Neither BMI nor intra-abdominal fat were seen to influence appendiceal visualization.

T1 Hyperintense Renal Lesions: Characterization with Diffusion-weighted MR Imaging versus Contrast-enhanced MR Imaging

To compare the performance of apparent diffusion coefficient (ADC) measurement obtained with diffusion-weighted (DW) magnetic resonance (MR) imaging in the characterization of non-fat-containing T1 hyperintense renal lesions with that of contrast material-enhanced MR imaging, with histopathologic analysis and follow-up imaging as the reference standards. Institutional review board approval was obtained for this HIPAA-compliant retrospective study, and the informed consent requirement was waived. Two independent observers retrospectively assessed MR images obtained in 41 patients with non-fat-containing T1 hyperintense renal lesions. The MR examination included acquisition of DW and contrast-enhanced T1-weighted images. For each index lesion, the observers assessed the (a) mean (+/- standard deviation) of ADC, (b) enhancement ratio, and (c) subtracted images for the presence of enhancement (confidence score, 1-5). Histopathologic analysis of renal cell carcinomas (RCCs) and follow-up imaging for benign lesions were the reference standards. ADCs of benign lesions and RCCs were compared. Receiver operating characteristic (ROC) curve analysis was performed to assess the accuracy of DW imaging, enhancement ratio, and subtraction for the diagnosis of RCC. A total of 64 lesions (mean diameter, 3.9 cm), including 38 benign T1 hyperintense cysts and 26 RCCs, were assessed. Mean ADCs of RCCs were significantly lower than those of benign cysts ([1.75 +/- 0.57] x 10(-3) mm(2)/sec vs [2.50 +/- 0.53] x 10(-3) mm(2)/sec, P < .0001). ADCs of solid and cystic portions of complex cystic RCCs were significantly different ([1.37 +/- 0.55] x 10(-3) mm(2)/sec vs [2.45 +/- 0.63] x 10(-3) mm(2)/sec, P < .0001). When data from both observers were pooled, area under the ROC curve, sensitivity, and specificity were 0.846, 71%, and 91%, respectively, for DW imaging; 0.865, 65%, and 96%, respectively, for enhancement ratio (at the excretory phase); and 0.861, 83%, and 89%, respectively, for subtraction (P = .48 and P = .85, respectively). The combination of DW imaging and subtraction resulted in area under the ROC curve, sensitivity, and specificity of 0.893, 87%, and 92%, respectively, with significantly improved reader confidence compared with subtraction alone (P = .041). The performance of DW imaging was equivalent to that of enhancement ratio in the characterization of T1 hyperintense renal lesions, with both methods having lower sensitivity than image subtraction without reaching significance.

Detection of Hepatocellular Carcinoma in Patients with Cirrhosis: Added Value of Coronal Reformations from Isotropic Voxels with 64-MDCT

The purpose of our study was to prospectively assess the added value of isotropic coronal reformations of the liver when using 64-MDCT for the detection of hepatocellular carcinoma (HCC). Seventy-one consecutive patients (60 men, 11 women; mean age, 65 years) suspected of having HCC underwent 64-MDCT with coronal reformations. A multiphasic CT protocol that included unenhanced, hepatic arterial, portal venous, and equilibrium phases was performed. Three independent, blinded readers interpreted the transverse scan alone, the coronal scan alone, and the combined transverse and coronal scans for the presence of HCC. Sensitivity, positive predictive value, area under the receiver operating characteristic curve (A(z)), and interpretation time were calculated for each reading session. Seventy-six HCC nodules were confirmed in 48 patients using histopathologic analysis or follow-up with long-term CT, MRI, or both (mean follow-up time, 12 months; range, 12-15 months) as the reference standard. Mean sensitivity, positive predictive value, and A(z) value for HCC detection were, respectively, 84% (191/228 readings), 91% (191/210 readings), and 0.85 for the transverse scan alone; 83% (189/228 readings), 93% (189/203 readings), and 0.86 for the coronal scan alone; and 87% (198/228 readings), 93% (198/213 readings), and 0.87 for combined interpretation of transverse and coronal scans. No comparisons were statistically significant. Forty-eight false-positive interpretations were recorded (19 for the transverse, 14 for the coronal, and 15 for the combined interpretation sets). The reading session in which combined transverse and coronal scans were available for interpretation showed significantly superior reader confidence for HCC detection as well as longer interpretation times (p<0.05 for both comparisons). The average reading time for the combined interpretation of transverse and coronal image sets (mean, 12.1+/-0.8 minutes) was significantly longer than for the transverse image set (7.4+/-1.5 minutes) or the coronal image set (7.1+/-1.3 minutes) (p<0.01). With 64-MDCT, the addition of isotropic coronal reformations to transverse images significantly improved reader confidence for the detection of HCC, with no statistically significant improvement in sensitivity, positive predictive value, or diagnostic accuracy (as determined by the A(z) value). This improvement comes at the cost of a longer interpretation time.

MR Diskography and CT Diskography with Gadodiamide–Iodinated Contrast Mixture for the Diagnosis of Foraminal Impingement

This study was designed to investigate whether the use of MR diskography would result in improved reader confidence over the use of CT diskography alone for evaluating foraminal impingement causing lumbar radiculopathy. Sixteen disk levels in 14 consecutive patients with suspected foraminal impingement causing lumbar radiculopathy were prospectively included in the study. A mixture of diluted gadodiamide and iodinated contrast material was injected at each disk level. After diskography, a CT scan (CT diskography) and T1-weighted fat-suppressed MR image (MR diskography) were obtained. Two spine radiologists and an orthopedic spine surgeon independently scored CT diskography and MR diskography for foraminal evaluation on a 3-point scale: 1, low confidence; 2, moderate confidence; and 3, high confidence. Each reader also assessed whether MR diskography showed an additional benefit over CT diskography with regard to the depiction of foraminal abnormalities only. Another radiologist reviewed conventional MR images focused on disk height and morphology. The reviewers' confidence scores for MR diskography were superior to those for CT diskography (reader 1, p = 0.00008; reader 2, p = 0.0008; reader 3, p = 0.0015) (p < 0.05). MR diskography was considered beneficial in 13 of 16 disk levels (reader 1), 14 of 16 (reader 2), and 14 of 16 (reader 3). MR diskography increased the confidence scores for the detection of foraminal impingement, especially in cases of severe disk degeneration, but did not show additional benefits in cases of an extensive vacuum in the disk or large disk extrusion. Simultaneous MR diskography and CT diskography with a mixture of gadodiamide and iodinated contrast material may be beneficial for evaluating foraminal impingement causing lumbar radiculopathy.

Small Bowel Obstruction

To assess performance of 16-multidetector computed tomography for small bowel obstruction with surgery as standard of reference. To assess the impact of coronal reformats on reader confidence, and to address management perspective and surgeon's assessment of coronal images. 16-Multidetector computed tomography scans of 30 patients presenting with clinical features of small bowel obstruction were reviewed. Five-millimeter axial images and 2.5-mm coronal images were available for interpretation. All patients had subsequent surgery. Two blinded readers independently reviewed axial and then coronal and axial (combination) images for transition site, etiology, and complications. Reader confidence was scored on a 3-point scale. A single surgeon evaluated studies for adequacy of scans and usefulness of coronal images. Results showed that the recorded accuracies were slightly higher for etiology, transition site, and complications using the combination data set; this reached statistical significance for etiology only (P = 0.08). There was no significant increase in scan evaluation time with addition of coronal images. Surgeon considered the coronal images more informative as compared with the axial images in 76.6% of cases. Coronal images generated at the scanner console are complementary to axials and improve reader confidence. Surgeons find coronal images more helpful than axial images for management.

Utility of Intravenously Administered Contrast Material at CT Colonography

To determine if intravenously administered contrast material improves overall reader confidence in the assessment of the colon, large-bowel wall conspicuity, and diagnostic accuracy in the detection of colorectal polyps and cancers at computed tomographic (CT) colonography. Two hundred patients underwent CT colonography in both supine and prone positions. A five-point scale was used to assess the effect of contrast enhancement on overall reader confidence and bowel wall conspicuity. Eighty-one patients underwent CT colonography with complete colonoscopic or surgical correlation; diagnostic accuracy was compared in 48 patients who received contrast material and 33 who did not. Bowel preparation was ideal in 38 (19%) of 200 patients. Enhanced prone CT images had significantly better scores for reader confidence (4.9 +/- 0.1 vs 4.6 +/- 0.1, P: <.005) and bowel wall conspicuity (4.6 +/- 0.2 vs 4.2 +/- 0.2, P: <.005) compared with those of nonenhanced prone images despite no significant difference in bowel distention (3.8 +/- 0.2 vs 3.9 +/- 0. 1, P: =.8). Enhancement significantly improved the ability to depict medium (6-9-mm) polyps (75% vs 58%, P: <.05). Three large (10-19-mm) polyps were detected only with contrast enhancement; two remained submerged despite dual positioning. The use of intravenously administered contrast material significantly improved reader confidence in the assessment of bowel wall conspicuity and the ability of CT colonography to depict medium polyps in suboptimally prepared colons.