Elaine M. Caoili

Renal Mass Core Biopsy: Accuracy and Impact on Clinical Management

OBJECTIVE The objective of our study was to determine the accuracy of imaging-guided percutaneous renal mass biopsy and its impact on clinical management. MATERIALS AND METHODS With institutional review board approval, we retrospectively reviewed imaging-guided renal biopsies performed by radiologists at our institution between February 1999 and July 2005. Patient records, pathology reports, and imaging studies were reviewed. Concordance of biopsy diagnosis and follow-up data was assessed. Significant impact on clinical management was determined in collaboration with two experienced urologists and was defined as a change from no therapy to therapy, including surgery, tumor ablation, chemotherapy, or radiation. RESULTS Two hundred seventy-six renal biopsies were performed during the study period. Of these, 123 were random biopsies and fine-needle technique was used for one; these 124 were excluded. One hundred fifty-two renal mass biopsies were performed using coaxial 18-gauge core needle technique in 125 patients (55 women, 70 men; average age, 60 years; range, 28-90 years). There were two (1.3%) postprocedural hematomas (one [0.7%] requiring blood transfusion) and one (0.7%) delayed renal pseudoaneurysm attributed to biopsy. No tumor seeding was identified. In 85 biopsies (56%), malignant neoplasm was found, 61 biopsies (40%) yielded benign findings, and six (4%) were nondiagnostic. The sensitivity for malignancy was 97.7%; specificity, 100%; positive predictive value, 100%; and negative predictive value, 100%. At least 92 (60.5%) biopsy results significantly impacted clinical management. CONCLUSION Imaging-guided percutaneous core needle biopsy of renal masses is safe and highly accurate. Tissue diagnosis alters clinical decision making in a majority of the cases and may allow a number of unnecessary nephrectomies to be avoided.

Frequency, outcome, and appropriateness of treatment of nonionic iodinated contrast media reactions

OBJECTIVE The objective of our study was to evaluate the frequency, outcome, and appropriateness of treatment of adults with acute allergiclike reactions related to IV-administered nonionic iodinated contrast media. MATERIALS AND METHODS For IV injections of nonionic iodinated contrast media between January 1, 1999, and December 31, 2005, contrast reaction reports and medical records of patients in whom contrast reactions occurred were reviewed. Data collected included patient sex and age, symptoms, reaction manifestations, treatment, and long-term sequelae. The appropriateness and efficacy of patient management were assessed. RESULTS Allergic-type reactions occurred in 545 (0.6%) of patients injected with nonionic iodinated contrast media: 418 (77%) reactions were mild, 116 (21%) were moderate, and 11 (2%) were severe. Two hundred twenty-one patients (41%) received treatment. The most commonly administered medication was diphenhydramine (145 patients or 27%). Corticosteroids were administered to 17 patients, nebulized albuterol to 16, and epinephrine to 15. Although 99% of the treatments did not result in any complication, three patients may have had short-term sequelae as a result of receiving a nonrecommended treatment. CONCLUSION Patients usually do well after developing acute allergiclike reactions to nonionic iodinated contrast media. Fortunately, in our series, this was true even in the rare cases in which the instituted treatment was considered to be inappropriate. Reacting patients rarely develop serious long-term sequelae.

Comparison of Acute Transient Dyspnea after Intravenous Administration of Gadoxetate Disodium and Gadobenate Dimeglumine: Effect on Arterial Phase Image Quality

PURPOSE To determine whether acute transient dyspnea and/or arterial phase image degradation occurs more or less often after intravenous administration of gadoxetate disodium than with intravenous administration of gadobenate dimeglumine. MATERIALS AND METHODS Institutional review board approval and patient consent were obtained for this prospective observational study. One hundred ninety-eight gadolinium-based contrast media administrations (99 with gadoxetate disodium [10 mL, n = 97; 8 mL, n = 1; 16 mL, n = 1] and 99 with gadobenate dimeglumine [0.1 mmol per kilogram of body weight, maximum dose, 20 mL]) for hepatobiliary indications were assessed in 192 patients. Subjective patient complaints were assessed. Objective respiratory motion degradation on T1-weighted precontrast and dynamic postcontrast (arterial, venous, or late dynamic or extracellular) magnetic resonance (MR) imaging datasets were independently assessed in a randomized, blinded fashion by five readers using a five-point scale, with mean scores of 4 or greater indicating severe motion. Comparisons between agents were made by using χ(2) or Fisher exact test, where appropriate. RESULTS Significantly more patient complaints of acute transient dyspnea occurred after gadoxetate disodium administration than gadobenate dimeglumine (14% [14 of 99] vs 5% [five of 99], P = .05). There were significantly more severely degraded arterial phase data sets for gadoxetate disodium than for gadobenate dimeglumine for both the general population (17% [17 of 99] vs 2% [two of 99], P = .0007) and the subpopulation with cirrhosis (19% [14 of 72] vs 3% [one of 37], P = .02). This effect did not extend to venous (1% [one of 99] vs 2% [two of 99], P > .99 [overall population]) or late dynamic or extracellular (2% [two of 99] vs 0% [zero of 99], P = .5 [overall population]) phases. No patient required treatment for self-limited dyspnea. CONCLUSION Intravenous gadoxetate disodium can result in acute self-limiting dyspnea that can have a deleterious effect on arterial phase MR image quality and occurs significantly more often than with intravenous gadobenate dimeglumine.

Dual-Energy CT with Single- and Dual-Source Scanners: Current Applications in Evaluating the Genitourinary Tract

Several promising clinical applications for dual-energy computed tomography (CT) in genitourinary imaging have been reported. Dual-energy CT not only provides excellent morphologic detail but also can supply material-specific and quantitative information that may be particularly useful in genitourinary imaging. Dual-energy CT has unique capabilities for characterizing renal lesions by quantifying iodine content and helping identify the mineral contents of renal stones, information that is important for patient care. Virtual unenhanced images reconstructed from dual-energy CT datasets can be useful for detecting calculi within the iodine-filled urinary collecting system, potentially reducing the need for an unenhanced scanning phase at CT urography. Although the underlying principles of dual-energy CT are the same regardless of scanner type, single-source dual-energy scanners with fast kilovoltage switching differ from dual-source dual-energy scanners both in image data acquisition and in processing methods; an understanding of these differences may help optimize dual-energy CT genitourinary protocols. Dual-energy CT performed with a dual-source scanner or with a single-source scanner with fast kilovoltage switching also has some important limitations. Further advances in scanning protocols and refinement of processing techniques to reduce image noise may lead to more widespread use of dual-energy CT.

Contrast Material–induced Nephrotoxicity and Intravenous Low-Osmolality Iodinated Contrast Material

PURPOSE To determine whether intravenous low-osmolality iodinated contrast material is associated with post-computed tomography (CT) acute kidney injury (AKI). MATERIALS AND METHODS Institutional review board approval was obtained and patient consent waived for this HIPAA-compliant retrospective study. CT examinations performed over a 10-year period in adult inpatients with sufficient serum creatinine (SCr) data were identified. A one-to-one propensity-matched matched cohort analysis with multivariate analysis of effects was performed with post-CT AKI as the primary outcome measure (10,121 unenhanced and 10,121 intravenous contrast-enhanced CT examinations in 20,242 patients). Propensity matching was performed with respect to likelihood of patient receiving intravenous contrast material (36 tested covariates). The primary endpoint was post-CT AKI by using Acute Kidney Injury Network SCr criteria; the secondary endpoint was post-CT AKI by using traditional SCr criteria for contrast material-induced nephrotoxicity (CIN; SCr increase ≥0.5 mg/dL [44.20 μmol/L] or ≥25%). Multivariate subgroup threshold analysis was performed (SCr <1.5 [<132.60 μmol/L]; ≥1.5 to ≥2.0 mg/dL [≥132.60 to ≥176.80 μmol/L]) and adjusted for assigned propensity scores. RESULTS Intravenous low-osmolality iodinated contrast material had a significant effect on the development of post-CT AKI for patients with pre-CT SCr levels of 1.6 mg/dL (141.44 μmol/L) or greater (odds ratio, 1.45; 95% confidence interval [CI]: 1.11, 1.89;P = .007). This effect strengthened as pre-CT SCr increased. Patients with stable SCr less than 1.5 mg/dL (132.60 μmol/L) were not at risk for developing CIN (P = .25, power > 95%). Both endpoints demonstrated similar results (eg, SCr ≥1.6 mg/dL [141.44 μmol/L] by using traditional CIN criteria: odds ratio, 1.64; 95% CI: 1.18, 2.28; P = .003). Post-CT AKI was prevalent in both the unenhanced and contrast-enhanced CT subgroups, and it increased with increases in pre-CT SCr. Many risk factors contributed to development of post-CT AKI, regardless of iodinated contrast material. CONCLUSION Intravenous low-osmolality iodinated contrast material is a nephrotoxic risk factor, but not in patients with a stable SCr level less than 1.5 mg/dL. Many factors other than contrast material can affect post-CT AKI rates.

Outcomes After Stereotactic Body Radiotherapy or Radiofrequency Ablation for Hepatocellular Carcinoma

PURPOSE Data guiding selection of nonsurgical treatment of hepatocellular carcinoma (HCC) are lacking. We therefore compared outcomes between stereotactic body radiotherapy (SBRT) and radiofrequency ablation (RFA) for HCC. PATIENTS AND METHODS From 2004 to 2012, 224 patients with inoperable, nonmetastatic HCC underwent RFA (n = 161) to 249 tumors or image-guided SBRT (n = 63) to 83 tumors. We applied inverse probability of treatment weighting to adjust for imbalances in treatment assignment. Freedom from local progression (FFLP) and toxicity were retrospectively analyzed. RESULTS RFA and SBRT groups were similar with respect to number of lesions treated per patient, type of underlying liver disease, and tumor size (median, 1.8 v 2.2 cm in maximum diameter; P = .14). However, the SBRT group had lower pretreatment Child-Pugh scores (P = .003), higher pretreatment alpha-fetoprotein levels (P = .04), and a greater number of prior liver-directed treatments (P < .001). One- and 2-year FFLP for tumors treated with RFA were 83.6% and 80.2% v 97.4% and 83.8% for SBRT. Increasing tumor size predicted for FFLP in patients treated with RFA (hazard ratio [HR], 1.54 per cm; P = .006), but not with SBRT (HR, 1.21 per cm; P = .617). For tumors ≥ 2 cm, there was decreased FFLP for RFA compared with SBRT (HR, 3.35; P = .025). Acute grade 3+ complications occurred after 11% and 5% of RFA and SBRT treatments, respectively (P = .31). Overall survival 1 and 2 years after treatment was 70% and 53% after RFA and 74% and 46% after SBRT. CONCLUSION Both RFA and SBRT are effective local treatment options for inoperable HCC. Although these data are retrospective, SBRT appears to be a reasonable first-line treatment of inoperable, larger HCC.

MDCT and Radiography of Wrist Fractures: Radiographic Sensitivity and Fracture Patterns

OBJECTIVE The purpose of our study was to determine which wrist fractures are not prospectively diagnosed at radiography using CT as a gold standard and to identify specific fracture patterns. MATERIALS AND METHODS Through a search of radiology records from January 1 to December 31, 2005, 103 consecutive patients were identified as having radiographic and CT examinations of the wrist. After excluding incomplete or nondiagnostic examinations and those with a greater than 6-week interval between imaging studies, the final study group consisted of 61 wrist examinations in 60 patients. Two musculoskeletal radiologists and one emergency radiologist blindly reviewed CT examinations, and each bone (scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate, metacarpals, distal radius, distal ulna) was categorized as normal or fractured, with agreement reached by consensus. Each prospective radiographic report was categorized as either normal or fracture/equivocal for each osseous structure. Results were compared using the chi-square and Fishers exact tests. RESULTS In the proximal carpal row, lunate and triquetrum fractures were often radiographically occult (0% and 20%, respectively, detected at radiography); whereas in the distal carpal row, trapezoid, capitate, and hamate fractures were often occult (0%, 0%, and 40% detected at radiography, respectively). Hamate fractures were significantly associated with metacarpal fractures, and distal radius fractures were associated with scaphoid and ulna fractures. CONCLUSION Thirty percent of wrist fractures were not prospectively diagnosed on radiography, suggesting that CT should be considered after a negative radiographic finding if clinically warranted. The location of a dorsal scaphoid avulsion fracture emphasizes the need for specific radiographic views or cross-sectional imaging for diagnosis.

Repeat Contrast Medium Reactions in Premedicated Patients: Frequency and Severity

PURPOSE To determine the frequency, type, and severity of breakthrough and repeat breakthrough reactions to iodinated low-osmolality contrast medium (LOCM) in patients who were premedicated with corticosteroids and antihistamines. MATERIALS AND METHODS Institutional review board approval was obtained, and informed consent was waived for this retrospective HIPAA-compliant analysis. One hundred ninety breakthrough allergic-like reactions to intravenous LOCM in 175 patients with a history of contrast medium reactions were reviewed. The repeat breakthrough reactions that resulted from 197 additional LOCM-enhanced examinations performed in 58 patients after the initial breakthrough reaction were also reviewed. The Fisher exact test was used to determine if certain risk factors were associated with an increased risk of a moderate or severe breakthrough reaction. Subgroup analysis was performed to determine if the contrast medium type, contrast medium volume, and/or time between the initial (index) and breakthrough reactions affected the breakthrough reaction severity. RESULTS Of 128 breakthrough reactions in which the index reaction severity was known, 103 (81%) were of a severity similar to that of the index reaction, 15 (12%) were less severe, and 10 (8%) were more severe. The severity of the breakthrough reactions in the patients with a mild index reaction was usually (in 94 [91%] of 103 reactions) mild. When the index reaction was severe, the breakthrough reaction was usually moderate or severe (in eight [42%] of 19 cases and four [67%] of six cases, respectively). The majority (174 [88%] of 197) of LOCM injections after the initial breakthrough reaction did not result in a repeat breakthrough reaction. Breakthrough reactions were significantly more likely to be moderate or severe in patients with a history of chronic oral corticosteroid use (P = .01), drug (P = .04) or severe (P < .001) allergies, or allergies to four or more allergens (P = .01). CONCLUSION Breakthrough reactions are usually similar in severity to the index reaction, and subsequent contrast medium injections usually do not induce repeat breakthrough reactions. Breakthrough reactions are more likely to be moderate or severe in patients with certain risk factors.

Distinguishing enhancing from nonenhancing renal lesions with fast kilovoltage-switching dual-energy CT

OBJECTIVE The purpose of this article is to evaluate the accuracy of dual-energy CT in distinguishing enhancing from nonenhancing or equivocally enhancing renal lesions. MATERIALS AND METHODS We retrospectively reviewed fast kilovoltage-switching dual-energy renal mass CT performed in 39 patients. On the contrast-enhanced dual-energy CT scans, renal lesions were graded subjectively for enhancement using iodine density images and iodine overlay images. Lesion iodine density was measured to identify an optimal threshold for detection of enhancement. Lesion attenuation measurements on unenhanced and contrast-enhanced scans were performed to identify enhancing (increase of > 20 HU) lesions, which were used as the reference standard. Sensitivity, specificity, and accuracy for detection of enhancement were calculated for the different dual-energy CT techniques. RESULTS Eighty-three renal lesions were evaluated. On the basis of attenuation measurements, there were 20 enhancing and 63 nonenhancing lesions. The sensitivity, specificity, and accuracy for the detection of enhancement according to the lesion appearance were 70%, 98.4%, and 91.6%, respectively, on iodine density images and were 85%, 90.5%, and 89.2%, respectively, on iodine overlay images generated from contrast-enhanced dual-energy CT scans. Of the various thresholds of measured lesion iodine density (1-3 mg/cm(3)), a threshold of 2 mg/cm(3) showed the highest accuracy for the detection of enhancement, with sensitivity, specificity, and accuracy of 90%, 93.7%, and 92.8%, respectively. CONCLUSION Fast kilovoltage-switching dual-energy CT is highly specific in excluding enhancement and moderately to highly sensitive in detecting enhancement of renal lesions. Of the available dual-energy CT techniques, iodine density measurement using a threshold of 2 mg/cm(3) is most accurate in distinguishing enhancing from nonenhancing renal lesions.

MRI of Sonographically Indeterminate Adnexal Masses

OBJECTIVE The purpose of this study was to assess the ability of MRI to characterize sonographically indeterminate adnexal masses and to define the sonographic features contributing to indeterminate diagnoses. MATERIALS AND METHODS Two blinded radiologists retrospectively reviewed the MRI examinations of 87 patients with 95 sonographically indeterminate adnexal masses. Reviewers determined the origin of a mass, its tissue content (cystic, solid, complex cystic, or cystic and solid), tissue characteristics (fat, blood, fibrous, or leiomyomatous), and benignity versus malignancy. Sonograms were reviewed by three reviewers to determine the origin of a mass, its tissue content, and reasons for an indeterminate diagnosis. Sensitivity and specificity of MRI were calculated, and agreement of sonography and MRI with the final diagnosis was determined using kappa statistics. The final diagnosis was determined by histopathology, surgical findings, or imaging or clinical follow-up. RESULTS The sensitivity of MRI for identifying malignancy (n = 5) was 100% and its specificity for benignity (n = 90) was 94%. Excellent agreement was seen between MRI and the final diagnosis for determining the origin (kappa = 0.93), tissue content (kappa = 0.98), and tissue characteristics (kappa = 0.91) of a mass. Sonography had poor agreement with the final diagnosis for the origin (kappa = 0.19) and tissue content (kappa = 0.33) of a mass. The main reasons for indeterminate sonographic diagnoses were the inability to determine origin because of location and large mass size and the appearances of purely solid or complex cystic masses. CONCLUSION Sonographically indeterminate adnexal masses of uncertain origin and solid or complex cystic content benefit from further evaluation with MRI, which is highly accurate for identifying the origin of a mass and characterizing its tissue content, obviating surgery.