Variability in Stiffness Assessment in a Thyroid Nodule Using Shear Wave Imaging.

PURPOSE: The aim of the study was to assess intrareader and interreader variability in placing a region of interest in the elastography color map in the thyroid nodule. METHOD AND MATERIALS: After institutional review board approval, elastograms were obtained by shear wave elastography from 38 individuals, with a total of 60 thyroid nodules. Two readers reviewed all images while blinded to the cytopathology or final histopathology results and to each other's measurements. For each image, readers first performed a qualitative assessment and recorded presence of stiff region(s) and number of stiff regions. Then, they placed a 3-mm circular region of interest on the stiffest region to quantify the mean and maximum stiffness in kilopascals. Intrareader and interreader agreement was summarized for categorical variables using Cohen κ and for continuous variables using the concordance correlation coefficient (CCC) and coefficient of variation. RESULTS: There was good overall intrareader and interreader agreement for the presence of stiff regions and number of stiff regions after classifying them as 0, 1, and greater than 1 regions (κ = 0.78-0.81 and 0.74-0.79, respectively). There was also good overall agreement for the the following quantitative measurements: mean kPa (CCC = 0.97 and 0.93) and max kPa (CCC = 0.97 and 0.93). The intrareader and interreader coefficient of variation was 13% and 21% for mean kPa and 14% and 21% for max kPa. CONCLUSIONS: There can be differences in measurement of stiffness by 2 different operators in softer nodules with shear wave imaging because of the lack of brighter areas on the color elastograms. A standardized technique is necessary to be able to compare results from 1 study to the next.

Comparing the diagnostic accuracy of contrast-enhanced computed tomographic angiography and gadolinium-enhanced magnetic resonance angiography for the assessment of hemodynamically significant transplant renal artery stenosis.

To compare diagnostic accuracy of contrast-enhanced computed tomographic angiography (CTA) and gadolinium-enhanced magnetic resonance angiography (MRA) for the assessment of hemodynamically significant transplant renal artery stenosis (TRAS). After institutional review board approval, records of 27 patients with TRAS confirmed on digital subtraction angiography (DSA) were retrospectively reviewed. A total of 13 patients had MRA and 14 had CTA before DSA. Two board-certified fellowship-trained radiologists, one each from interventional radiology and body imaging blindly reviewed the DSA and CTA or MRA data, respectively. Sensitivity (SN), specificity (SP), positive predictive value, and negative predictive value of MRA and CTA were estimated using 50% stenosis as the detection threshold for significant TRAS. These parameters were compared between modalities using the Fisher exact test. Bias between MRA or CTA imaging and DSA was tested using the Wilcoxon signed-rank test. Two patients were excluded from the MRA group owing to susceptibility artifacts obscuring the TRAS. The correlation between MRA and DSA measurements of stenosis was r = 0.57 (95% CI:-0.02, 0.87; P = 0.052) and between CTA and DSA measurements was r = 0.63 (95% CI: 0.14, 0.87; P = 0.015); the difference between the 2 techniques was not significant (P = 0.7). Both imaging modalities tended to underestimate the degree of stenosis when compared with DSA. MRA group (SN and SP: 56% and 100%, respectively) and CTA group (SN and SP: 81% and 67%, respectively). There were no significant differences in detection performance between modalities (P>0.3 for all measures). We did not find that either modality had any advantage over the other in terms of measuring or detecting significant stenosis. Accordingly, MRA may be preferred over CTA after positive color Doppler ultrasound screening when not contraindicated owing to lack of ionizing radiation or nephrotoxic iodinated contrast. However, susceptibility of artifacts owing to surgical clips at the anastomosis may limit diagnostic utility of MRA as found in 2 of 13 patients. Trend towards no significant difference between the CTA and enhanced MRA in the detection of hemodynamically significant TRAS.

EXIT procedure: technique and indications with prenatal imaging parameters for assessment of airway patency.

Successful management of fetal conditions in which airway obstruction is anticipated is now possible because of advances in prenatal imaging and the development of innovative techniques to secure the fetal airway before complete separation of the fetus from the maternal circulation. Fetal ultrasonography and fetal magnetic resonance imaging are complementary imaging modalities in the assessment of fetuses with potential airway obstruction. The ex utero intrapartum therapy (EXIT) procedure is used to secure the fetal airway before complete delivery of the fetus. However, successful intrapartum treatment of fetuses who may need prolonged placental support depends on a multidisciplinary assessment in which the benefits of the EXIT procedure for the fetus are weighed against the risk of maternal complications that may occur during prolongation of the intrapartum period to secure the fetal airway. This multidisciplinary approach requires an understanding of the types of lesions in which intrapartum fetal airway access would be beneficial, a knowledge of the prenatal images that would best delineate the anatomic defect and thus help guide the best approach to securing the airway, and consensus and coordination among medical ethicists, radiologists, obstetric anesthesiologists and obstetricians, pediatric surgeons and anesthesiologists, and neonatologists.