Abdominal fellowship-trained versus generalist radiologist accuracy when interpreting MR and CT for the diagnosis of appendicitis.

OBJECTIVES: To compare the diagnostic accuracy of generalist radiologists working in a community setting against abdominal radiologists working in an academic setting for the interpretation of MR when diagnosing acute appendicitis among emergency department patients. METHODS: This observational study examined MR image interpretation (non-contrast MR with diffusion-weighted imaging and intravenous contrast-enhanced MR) from a prospectively enrolled cohort at an academic hospital over 18 months. Eligible patients had an abdominopelvic CT ordered to evaluate for appendicitis and were > 11 years old. The reference standard was a combination of surgery and pathology results, phone follow-up, and chart review. Six radiologists blinded to clinical information, three each from community and academic practices, independently interpreted MR and CT images in random order. We calculated test characteristics for both individual and group (consensus) diagnostic accuracy then performed Chi-square tests to identify any differences between the subgroups. RESULTS: Analysis included 198 patients (114 women) with a mean age of 31.6 years and an appendicitis prevalence of 32.3%. For generalist radiologists, the sensitivity and specificity (95% confidence interval) were 93.8% (84.6-98.0%) and 88.8% (82.2-93.2%) for MR and 96.9% (88.7-99.8%) and 91.8% (85.8-95.5%) for CT. For fellowship-trained radiologists, the sensitivity and specificity were 96.9% (88.2-99.5%) and 89.6% (82.8-94%) for MR and 98.4% (90.5-99.9%) and 93.3% (87.3-96.7%) for CT. No statistically significant differences were detected between radiologist groups (p = 1.0, p = 0.53, respectively) or when comparing MR to CT (p = 0.21, p = 0.17, respectively). CONCLUSIONS: MR is a reliable, radiation-free imaging alternative to CT for the evaluation of appendicitis in community-based generalist radiology practices. KEY POINTS: • There was no significant difference in MR image interpretation accuracy between generalist and abdominal fellowship-trained radiologists when evaluating sensitivity (p = 1.0) and specificity (p = 0.53). • There was no significant difference in accuracy comparing MR to CT imaging for diagnosing appendicitis for either sensitivity (p = 0.21) or specificity (p = 0.17). • With experience, generalist radiologists enhanced their MR interpretation accuracy as demonstrated by improved interpretation sensitivity (OR 2.89 CI 1.44-5.77, p = 0.003) and decreased mean interpretation time (5 to 3.89 min).

Prospective evaluation of MRI compared with CT for the etiology of abdominal pain in emergency department patients with concern for appendicitis.

BACKGROUND: Computed tomography (CT) is commonly used in the Emergency Department (ED) to evaluate patients with abdominal pain, but exposes them to ionizing radiation, a possible carcinogen. MRI does not utilize ionizing radiation and may be an alternative. PURPOSE: To compare the sensitivity of MRI and CT for acute abdominopelvic ED diagnoses. STUDY TYPE: Prospective, observational cohort. POPULATION: ED patients ≥12 years old and undergoing CT for possible appendicitis. FIELD STRENGTH/SEQUENCE: 1.5 T MRI, including T1 -weighted, T2 -weighted, and diffusion-weighted imaging sequences. ASSESSMENT: Three radiologists independently interpreted each MRI and CT image set separately and blindly, using a standard case report form. Assessments included likelihood of appendicitis, presence of an alternative diagnosis, and likelihood that the alternative diagnosis was causing the patient's symptoms. An expert panel utilized chart review and follow-up phone interviews to determine all final diagnoses. Times to complete image acquisition and image interpretation were also calculated. STATISTICAL TESTS: Sensitivity was calculated for each radiologist and by consensus (≥2 radiologists in agreement) and are reported as point estimates with 95% confidence intervals. Two-sided hypothesis tests comparing the sensitivities of the three image types were conducted using Pearson's chi-squared test with the traditional significance level of P = 0.05. RESULTS: There were 15 different acute diagnoses identified on the CT/MR images of 113 patients. Using individual radiologist interpretations, the sensitivities of noncontrast-enhanced MRI (NCE-MR), contrast-enhanced MR (CE-MR), and CT for any acute diagnosis were 77.0% (72.6-81.4%), 84.2% (80.4-88.0%), and 88.7% (85.5-92.1%). Sensitivity of consensus reads was 82.0% (74.9-88.9%), 87.1% (81.0-93.2%), 92.2% (87.3-97.1%), respectively. There was no difference in sensitivities between CE-MR and CT by individual (P = 0.096) or consensus interpretations (P = 0.281), although NCE-MR was inferior to CT in both modes of analysis (P < 0.001, P = 0.031, respectively). DATA CONCLUSION: The sensitivity of CE-MR was similar to CT when diagnosing acute, nontraumatic abdominopelvic pathology in our cohort. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1651-1658.

Prospective Comparison of the Diagnostic Accuracy of MR Imaging versus CT for Acute Appendicitis.

Purpose To compare the accuracy of magnetic resonance (MR) imaging with that of computed tomography (CT) for the diagnosis of acute appendicitis in emergency department (ED) patients. Materials and Methods This was an institutional review board-approved, prospective, observational study of ED patients at an academic medical center (February 2012 to August 2014). Eligible patients were nonpregnant and 12- year-old or older patients in whom a CT study had been ordered for evaluation for appendicitis. After informed consent was obtained, CT and MR imaging (with non-contrast material-enhanced, diffusion-weighted, and intravenous contrast-enhanced sequences) were performed in tandem, and the images were subsequently retrospectively interpreted in random order by three abdominal radiologists who were blinded to the patients' clinical outcomes. Likelihood of appendicitis was rated on a five-point scale for both CT and MR imaging. A composite reference standard of surgical and histopathologic results and clinical follow-up was used, arbitrated by an expert panel of three investigators. Test characteristics were calculated and reported as point estimates with 95% confidence intervals (CIs). Results Analysis included images of 198 patients (114 women [58%]; mean age, 31.6 years ± 14.2 [range, 12-81 years]; prevalence of appendicitis, 32.3%). The sensitivity and specificity were 96.9% (95% CI: 88.2%, 99.5%) and 81.3% (95% CI: 73.5%, 87.3%) for MR imaging and 98.4% (95% CI: 90.5%, 99.9%) and 89.6% (95% CI: 82.8%, 94.0%) for CT, respectively, when a cutoff point of 3 or higher was used. The positive and negative likelihood ratios were 5.2 (95% CI: 3.7, 7.7) and 0.04 (95% CI: 0, 0.11) for MR imaging and 9.4 (95% CI: 5.9, 16.4) and 0.02 (95% CI: 0.00, 0.06) for CT, respectively. Receiver operating characteristic curve analysis demonstrated that the optimal cutoff point to maximize accuracy was 4 or higher, at which point there was no difference between MR imaging and CT. Conclusion The diagnostic accuracy of MR imaging was similar to that of CT for the diagnosis of acute appendicitis.

Percutaneous liver biopsy and revised coagulation guidelines: a 9-year experience.

PURPOSE: To retrospectively review revised pre-procedural coagulation guidelines for percutaneous liver biopsy to determine whether their implementation is associated with increased hemorrhagic complications on a departmental scale. Secondary endpoints were to determine the effect of this change on pre-procedural blood product (FFP and platelet) utilization, to evaluate the impact of administered blood products on hemorrhagic complications, and to determine whether bleeding complications were related to INR and platelet levels. MATERIALS AND METHODS: This IRB-approved, HIPAA-compliant, retrospective study reviewed 1846 percutaneous liver biopsies in 1740 patients, comparing biopsies performed, while SIR consensus pre-procedural coagulation guidelines were in place (INR ≤ 1.5, platelets ≥50,000 µL) to those performed after departmental implementation of revised, less stringent guidelines (INR ≤ 2.0, platelets ≥25,000 µL). RESULTS: On a departmental scale, there were significantly fewer hemorrhagic complications in the population of patients treated after adoption of less stringent guidelines as compared to those treated under the SIR guidelines (1.6% vs. 3.4%, p = 0.0192) despite a significant decrease in pre-procedural FFP (0.8% vs. 3.9%, p < 0.001) and platelet transfusions (0.3% vs. 1.2%, p = 0.021). Individual patient hemorrhagic complication rates significantly increased as INR increased (p = 0.006) and platelet counts decreased (p = 0.004), but pre-procedural FFP (p = 0.64) and/or platelet transfusion (p = 0.5) did not have a significant impact on hemorrhagic complication rates. CONCLUSION: Implementation of less stringent pre-procedural coagulation parameter guidelines for percutaneous liver biopsy (INR ≤ 2.0, platelets ≥25,000 µL) did not result in an increase in departmental hemorrhagic complication rates but did significantly decrease pre-procedural FFP/platelet administration. An individual patient's bleeding risk does increase as INR increases and platelets decrease, but pre-procedural FFP and/or platelet transfusion did not mitigate that increased risk.

Diagnostic Accuracy of MRI Versus CT for the Evaluation of Acute Appendicitis in Children and Young Adults.

OBJECTIVE: Appendicitis is frequently diagnosed in the emergency department, most commonly using CT. The purpose of this study was to compare the diagnostic accuracy of contrast-enhanced MRI with that of contrast-enhanced CT for the diagnosis of appendicitis in adolescents when interpreted by abdominal radiologists and pediatric radiologists. SUBJECTS AND METHODS: Our study included a prospectively enrolled cohort of 48 patients (12-20 years old) with nontraumatic abdominal pain who underwent CT and MRI. Fellowship-trained abdominal and pediatric radiologists reviewed all CT and MRI studies in randomized order, blinded to patient outcome. Likelihood for appendicitis was rated on a 5-point scale (1, definitely not appendicitis; 5, definitely appendicitis) for CT, the unenhanced portion of the MRI, and the entire contrast-enhanced MRI study. ROC curves were generated and AUC compared for each scan type for all six readers and then stratified by radiologist type. Image test characteristics, interrater reliability, and reading times were compared. RESULTS: Sensitivity and specificity were 85.9% (95% CI, 76.2-92.7%) and 93.8% (95% CI, 89.7-96.7%) for unenhanced MRI, 93.6% (95% CI, 85.6-97.9%) and 94.3% (95% CI, 90.2-97%) for contrast-enhanced MRI, and 93.6% (95% CI, 85.6-97.9%) and 94.3% (95% CI, 90.2-97%) for CT. No difference was found in the diagnostic accuracy or interpretation time when comparing abdominal radiologists to pediatric radiologists (CT, 3.0 min vs 2.8 min; contrast-enhanced MRI, 2.4 min vs 1.8 min; unenhanced MRI, 1.5 min vs 2.3 min). Substantial agreement between abdominal and pediatric radiologists was seen for all methods (κ = 0.72-0.83). CONCLUSION: The diagnostic accuracy of MRI to diagnose appendicitis was very similar to CT. No statistically significant difference in accuracy was observed between imaging modality or radiologist subspecialty.

Pulmonary Intraparenchymal Blood Patching Decreases the Rate of Pneumothorax-Related Complications following Percutaneous CT-Guided Needle Biopsy.

PURPOSE: To investigate whether an autologous intraparenchymal blood patch (IPB) reduces the rate of pneumothorax-related complications associated with computed tomography (CT)-guided lung biopsies. MATERIALS AND METHODS: This study included 834 patients: 482 who received an IPB and 352 who did not. Retrospective review was performed of all CT-guided lung biopsies performed at a single institution between August 2006 and September 2013. Patients were excluded if no aerated lung was crossed. The rate of pneumothorax, any associated intervention (eg, catheter placement, aspiration), chest tube placement, and chest tube replacement requiring hospital admission were compared by linear and multiple regression analysis. RESULTS: Patients who received an IPB had a significantly lower rate of pneumothorax (145 of 482 [30%] vs 154 of 352 [44%]; P < .0001), pneumothorax-related intervention (eg, catheter aspiration, pleural blood patch, chest tube placement; 43 of 482 [8.9%] vs 85 of 352 [24.1%]; P < .0001), and chest tube placement along with other determinants requiring hospital admission (18 of 482 [3.7%] vs 27 of 352 [7.7%]; P < .0001). No complications related to the IPB were noted in the study group. CONCLUSIONS: Autologous IPB placement is associated with a decreased rate of pneumothorax and associated interventions, including chest tube placement and hospital admission, after CT-guided lung biopsies, with no evidence of any adverse effects. These results suggest that an IPB is safe and effective and should be considered when aerated lung is traversed while performing a CT-guided lung biopsy.

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.

Evaluation of a thermoprotective gel for hydrodissection during percutaneous microwave ablation: in vivo results.

PURPOSE: To evaluate whether thermoreversible poloxamer 407 15.4 % in water (P407) can protect non-target tissues adjacent to microwave (MW) ablation zones in a porcine model. MATERIALS AND METHODS: MW ablation antennas were placed percutaneously into peripheral liver, spleen, or kidney (target tissues) under US and CT guidance in five swine such that the expected ablation zones would extend into adjacent diaphragm, body wall, or bowel (non-target tissues). For experimental ablations, P407 (a hydrogel that transitions from liquid at room temperature to semi-solid at body temperature) was injected into the potential space between target and non-target tissues, and the presence of a gel barrier was verified on CT. No barrier was used for controls. MW ablation was performed at 65 W for 5 min. Thermal damage to target and non-target tissues was evaluated at dissection. RESULTS: Antennas were placed 7 ± 3 mm from the organ surface for both control and gel-protected ablations (p = 0.95). The volume of gel deployed was 49 ± 27 mL, resulting in a barrier thickness of 0.8 ± 0.5 cm. Ablations extended into non-target tissues in 12/14 control ablations (mean surface area = 3.8 cm(2)) but only 4/14 gel-protected ablations (mean surface area = 0.2 cm(2); p = 0.0005). The gel barrier remained stable at the injection site throughout power delivery. CONCLUSION: When used as a hydrodissection material, P407 protected non-targeted tissues and was successfully maintained at the injection site for the duration of power application. Continued investigations to aid clinical translation appear warranted.

Microwave ablation of hepatic tumors abutting the diaphragm is safe and effective.

OBJECTIVE: The purpose of this study was to evaluate the incidence of clinically significant diaphragmatic injuries and local tumor progression after microwave ablation of hepatic tumors abutting the diaphragm. MATERIALS AND METHODS: This retrospective study included 55 peripheral hepatic tumors abutting the diaphragm treated by microwave ablation versus a control group of 15 centrally located tumors. Treated tumors were further subdivided according to the use of artificial ascites (fluid vs no fluid) and whether instilled fluid achieved displacement of the liver surface away from the diaphragm (displaced vs nondisplaced). Measurements of tumor size, distance to the diaphragm, ablation zone size, displacement distance, length of the ablation zone along the liver capsule, diaphragm thickness, diaphragmatic hernia, and local tumor progression were made on pre- and postablation CT and MRI. The electronic medical record was reviewed for patient self-reported pain scores and other symptoms. Data were analyzed by use of the Kruskal-Wallis and Fisher exact tests. RESULTS: There were no cases of diaphragmatic hernia in peripheral or central tumors. Postablation diaphragm thickness was higher in peripheral hepatic tumors than in control tumors. Peripheral tumors had an overall higher incidence of postprocedure shoulder pain (18% vs 0%) and local tumor progression (5.5% vs 0%) compared with control tumors, but these differences did not achieve statistical significance (p = 0.2 and p = 1, respectively). CONCLUSION: Our study shows that microwave ablation of peridiaphragmatic hepatic tumors is safe, without incidence of diaphragmatic hernia, and can be performed with a low rate of local tumor progression.

High-powered microwave ablation of t1a renal cell carcinoma: safety and initial clinical evaluation.

PURPOSE: Percutaneous radiofrequency ablation and cryoablation are accepted alternative treatments for small renal cell carcinomas (RCC) in high-risk patients. The recent development of high-powered microwave (MW) ablation offers theoretical advantages over existing ablation systems, including higher tissue temperatures, more reproducible ablation zones, and shorter procedural times. The purpose of this study is to review the feasibility, safety, and early efficacy of a novel high-powered percutaneous MW ablation system to treat RCC. METHODS: An institutional database identified 53 consecutive patients with biopsy-proven RCC ≤4 cm (55 tumors) who were treated with percutaneous MW ablation using a novel MW ablation system. All patients had percutaneous renal mass biopsy, which identified RCC before ablation. Postprocedure follow-up imaging was performed by contrast-enhanced computed tomography or magnetic resonance imaging. RESULTS: Mean patient age was 66 years and 81% of patients were male. RCC subtypes included clear cell (n=25), papillary (n=12), and unspecified (n=18) and Fuhrman grades 1, 2, 3, and ungraded in 15, 25, 1, and 14 patients, respectively. The mean tumor diameter was 2.6 cm (range 0.8-4.0 cm). Six low-grade complications were recorded during 53 (11.3%) procedures: five Clavien Grade 1 (urine retention, fluid overload, and atrial fibrillation) and one Grade 2 (hemorrhage requiring transfusion). The postprocedure estimated glomerular filtration rate was not significantly changed from preprocedure levels (median: -1.1%, p=0.10). Median follow-up was 8 months (interquartile range [IQR] 5-18.25) with 0/38 (0%) patients demonstrating evidence of local recurrence or metastasis during surveillance imaging. CONCLUSIONS: Use of a high-powered MW ablation system for the treatment of T1a RCC is feasible, safe, and efficacious with short-term follow-up. A longer follow-up is warranted to evaluate oncologic outcomes.

Learning radiology a survey investigating radiology resident use of textbooks, journals, and the internet.

RATIONALE AND OBJECTIVES: We surveyed radiology residents to understand which information sources residents use to learn radiology. MATERIALS AND METHODS: A 15-question survey on learning resources was given to radiology residents at one institution. The survey queried residents about their preferences for sources when encountering a question in the reading room and when attempting to learn radiology and about the frequency with which they read radiology/medical journals. Residents ranked Internet sites for these learning purposes. The IRB gave administrative approval for the survey. RESULTS: All residents (60 of 60) completed the survey. When a question is encountered in the reading room, 50 of 60 (83%) respondents prefer to use the Internet as a first-line resource, and 15% prefer a textbook. When using the Internet, 46 of 60 (77%) residents use Google as their first source, 12% use eMedicine, 3% use StatDx, 3% use UpToDate, and 2% use RSNA online journals. eMedicine was the most popular second resource at 65%. Of 60, 59 (98%) residents prefer to use physician/scientist professional Web sites (e.g., eMedicine) rather than consumer/patient-oriented Web sites. When using the Internet to learn radiology, 32% of residents prefer AuntMinnie, 30% use Edactic.com, 22% use ACR Case-In-Point, 3% use www.learningradiology.com, 2% use radquiz.com, and 2% use RadioGraphics online. On average, residents listed 6.2 Internet sites. For textbook learning, 58% of residents prefer case review or requisite books, while 32% prefer traditional textbooks. The mean number of textbooks owned is 5.3, while the mean number of case review or requisite books is 5.4. Of 60 residents, 8 own most or all the case review and requisite books. Twenty-eight percent of residents read radiology textbooks daily; 45%, weekly; 8%, monthly; and 15%, occasionally. Twenty-three percent of residents read radiology journals monthly; 15%, quarterly; 37%, occasionally; and 23%, never. Five percent of residents read medical journals (e.g., The New England Journal of Medicine) monthly; 2%, quarterly; 48%, occasionally; and 45%, never. CONCLUSION: Currently, residents prefer the Internet when researching a question, with Google as the Web site most commonly used. Case review or requisite books are more commonly used than are traditional textbooks. Radiology resident learning has rapidly shifted from traditional textbooks and journals to the Internet and short case review books.