Microbubble Contrast-Enhanced Transcutaneous Ultrasound Enables Real-Time Spinal Cord Perfusion Monitoring Following Posterior Cervical Decompression.

BACKGROUND: Ultrasound imaging is inexpensive, portable, and widely available. The development of a real-time transcutaneous spinal cord perfusion monitoring system would allow more precise targeting of mean arterial pressure goals following acute spinal cord injury (SCI). There has been no prior demonstration of successful real-time cord perfusion monitoring in humans. METHODS: Four adult patients who had undergone posterior cervical decompression and instrumentation at a single center were enrolled into this prospective feasibility study. All participants had undergone cervical laminectomies spanning ≥2 contiguous levels ≥2 months prior to inclusion with no history of SCI. The first 2 underwent transcutaneous ultrasound without contrast and the second 2 underwent contrast-enhanced ultrasound (CEUS) with intravenously injected microbubble contrast. RESULTS: Using noncontrast ultrasound with or without Doppler (n = 2), the dura, spinal cord, and vertebral bodies were apparent however ultrasonography was insufficient to discern intramedullary perfusion or clear white-gray matter differentiation. With application of microbubble contrast (n = 2), it was possible to quantify differential spinal cord perfusion within and between cross-sectional regions of the cord. Further, it was possible to quantify spinal cord hemodynamic perfusion using CEUS by measuring peak signal intensity and the time to peak signal intensity after microbubble contrast injection. Time-intensity curves were generated and area under the curves were calculated as a marker of tissue perfusion. CONCLUSIONS: CEUS is a viable platform for monitoring real-time cord perfusion in patients who have undergone prior cervical laminectomies. Further development has the potential to change clinical management acute SCI by tailoring treatments to measured tissue perfusion parameters.

Diagnostic Imaging and Medical Management of Acute Left-Sided Colonic Diverticulitis : A Systematic Review.

BACKGROUND: Clinicians need to better understand the value of computed tomography (CT) imaging and nonsurgical treatment options to manage acute left-sided colonic diverticulitis. PURPOSE: To evaluate CT imaging, outpatient treatment of uncomplicated diverticulitis, antibiotic treatment, and interventional radiology for patients with complicated diverticulitis. DATA SOURCES: MEDLINE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Embase, CINAHL, and ClinicalTrials.gov from 1 January 1990 through 16 November 2020. STUDY SELECTION: Existing systematic reviews of CT imaging accuracy, as well as randomized trials and adjusted nonrandomized comparative studies reporting clinical or patient-centered outcomes. DATA EXTRACTION: 6 researchers extracted study data and risk of bias, which were verified by an independent researcher. The team assessed strength of evidence across studies. DATA SYNTHESIS: Based on moderate-strength evidence, CT imaging is highly accurate for diagnosing acute diverticulitis. For patients with uncomplicated acute diverticulitis, 6 studies provide low-strength evidence that initial outpatient and inpatient management have similar risks for recurrence or elective surgery, but they provide insufficient evidence regarding other outcomes. Also, for patients with uncomplicated acute diverticulitis, 5 studies comparing antibiotics versus no antibiotics provide low-strength evidence that does not support differences in risks for treatment failure, elective surgery, recurrence, posttreatment complications, and other outcomes. Evidence is insufficient to determine choice of antibiotic regimen (7 studies) or effect of percutaneous drainage (2 studies). LIMITATIONS: The evidence base is mostly of low strength. Studies did not adequately assess heterogeneity of treatment effect. CONCLUSION: Computed tomography imaging is accurate for diagnosing acute diverticulitis. For patients with uncomplicated diverticulitis, no differences in outcomes were found between outpatient and inpatient care. Avoidance of antibiotics for uncomplicated acute diverticulitis may be safe for most patients. The evidence is too sparse for other evaluated questions. PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality and American College of Physicians. (PROSPERO: CRD42020151246).

Abnormal spinal cord motion at the craniocervical junction in hypermobile Ehlers-Danlos patients.

OBJECTIVE: The craniocervical junction (CCJ) is anatomically complex and comprises multiple joints that allow for wide head and neck movements. The thecal sac must adjust to such movements. Accordingly, the thecal sac is not rigidly attached to the bony spinal canal but instead tethered by fibrous suspension ligaments, including myodural bridges (MDBs). The authors hypothesized that pathological spinal cord motion is due to the laxity of such suspension bands in patients with connective tissue disorders, e.g., hypermobile Ehlers-Danlos syndrome (EDS). METHODS: The ultrastructure of MDBs that were intraoperatively harvested from patients with Chiari malformation was investigated with transmission electron microscopy, and 8 patients with EDS were compared with 8 patients without EDS. MRI was used to exclude patients with EDS and craniocervical instability (CCI). Real-time ultrasound was used to compare the spinal cord at C1-2 of 20 patients with EDS with those of 18 healthy control participants. RESULTS: The ultrastructural damage of the collagen fibrils of the MDBs was distinct in patients with EDS, indicating a pathological mechanical laxity. In patients with EDS, ultrasound revealed increased cardiac pulsatory motion and irregular displacement of the spinal cord during head movements. CONCLUSIONS: Laxity of spinal cord suspension ligaments and the associated spinal cord motion disorder are possible pathogenic factors for chronic neck pain and headache in patients with EDS but without radiologically proven CCI.

Inclusion of Thyroid Nodule Location in American College of Radiology TI-RADS Scoring: Impact on System Performance.

Emerging data suggest that the location of thyroid nodules influences malignancy risk. The purpose of this study was to explore the impact of including location in American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) scoring. Four of five revised scoring algorithms that added 1 or 2 points to higher-risk locations were associated with lowered accuracy due to lower specificity. However, an algorithm that added 1 point to isthmic nodules did not differ significantly from ACR TI-RADS in accuracy; one additional isthmic cancer was diagnosed for each 10.3 additional benign nodules recommended for biopsy.

Effect of Decreasing the ACR TI-RADS Point Assignment for Punctate Echogenic Foci When They Occur in Mixed Solid and Cystic Thyroid Nodules.

OBJECTIVE. Using the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS), this study sought to determine whether decreasing the point assignment for punctate echogenic foci in mixed solid and cystic nodules would reduce the number of benign mixed solid and cystic nodules that were biopsied and would not substantially increase the number of missed mixed carcinomas MATERIALS AND METHODS. A multiinstitutional database of 3422 pathologically proven thyroid nodules was evaluated to identify all mixed solid and cystic nodules with punctate echogenic foci. We determined the numbers of mixed benign and malignant nodules that would receive ACR TI-RADS recommendations of fine-needle aspiration, follow-up, and no further evaluation if the points assigned to punctate echogenic foci were changed from 3 points to 1 or 2 points. RESULTS. A total of 287 mixed nodules were adequately characterized for evaluation. When the number of points assigned to punctate echogenic foci was changed from 3 points to 1 point, the point categories changed for 198 mixed nodules. Seven carcinomas would not undergo biopsy, but six of those seven would receive follow-up, and 44 benign nodules would not undergo biopsy. When 2 points were assigned to punctate echogenic foci, the point categories changed for 66 mixed nodules. Three carcinomas would not undergo biopsy, but all three of these would receive follow-up, and eight benign nodules would not undergo biopsy. CONCLUSION. Consideration should be given to decreasing the number of points assigned to punctate echogenic foci in mixed solid and cystic thyroid nodules, given the substantial decrease in the number of benign nodules requiring biopsy and the recommendation of follow-up for any carcinoma 1 cm or larger that did not undergo biopsy.

Analysis of Malignant Thyroid Nodules That Do Not Meet ACR TI-RADS Criteria for Fine-Needle Aspiration.

OBJECTIVE. Compared with other guidelines, the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) has decreased the number of nodules for which fine-needle aspiration is recommended. The purpose of this study was to evaluate the characteristics of malignant nodules that would not be biopsied when the ACR TI-RADS recommendations are followed. MATERIALS AND METHODS. We retrospectively reviewed a total of 3422 thyroid nodules for which a definitive cytologic diagnosis, a definitive histologic diagnosis, or both diagnoses as well as diagnostic ultrasound (US) examinations were available. All nodules were categorized using the ACR TI-RADS, and they were divided into three groups according to the recommendation received: fine-needle aspiration (group 1), follow-up US examination (group 2), or no further evaluation (group 3). RESULTS. Of the 3422 nodules, 352 were malignant. Of these, 240 nodules were assigned to group 1, whereas 72 were assigned to group 2 and 40 were included in group 3. Sixteen of the 40 malignant nodules in group 3 were 1 cm or larger, and, on the basis of analysis of the sonographic features described in the ACR TI-RADS, these nodules were classified as having one of five ACR TI-RADS risk levels (TR1-TR5), with one nodule classified as a TR1 nodule, eight as TR2 nodules, and seven as TR3 nodules. If the current recommendation of no follow-up for TR2 nodules was changed to follow-up for nodules 2.5 cm or larger, seven additional malignant nodules and 316 additional benign nodules would receive a recommendation for follow-up. If the current size threshold (1.5 cm) used to recommend US follow-up for TR3 nodules was decreased to 1.0 cm, seven additional malignant nodules and 118 additional benign nodules would receive a recommendation for follow-up. CONCLUSION. With use of the ACR TI-RADS, most malignant nodules that would not be biopsied would undergo US follow-up, would be smaller than 1 cm, or would both undergo US follow-up and be smaller than 1 cm. Adjusting size thresholds to decrease the number of missed malignant nodules that are 1 cm or larger would result in a substantial increase in the number of benign nodules undergoing follow-up.

In Vivo Ultrasound Imaging of the Spinal Cord and Subarachnoid Space at the C1-C2 Level in Healthy Adult Subjects.

ABSTRACT: Ultrasound (US) imaging of the spinal canal is applied in early infants before formation of posterior spine bony elements. Here, we demonstrate for the first time in adult healthy subjects that excellent visualization of intrathecal structures at the level of C1-C2 is possible by transcutaneous US in flexion, extension, and neutral head positions through the soft tissue US window between C1-C2. We show with US that the posterior subarachnoid space increases significantly in head extension. Accordingly, C1-C2 US guidance can facilitate cervical myelography. In addition, we suggest that US of the C1-C2 spine level may offer an adjunct tool to diagnosing structural abnormalities in the setting of traumatic, congenital, or degenerative pathologies of the craniocervical junction.

Reclaiming Hands-on Ultrasound for Radiology With a Simulation-Based Ultrasound Curriculum for Radiology Residents.

Hands-on ultrasound training is included in the curriculum of many medical specialties and is increasingly incorporated into medical school curricula. Despite published curricula for ultrasound training in these specialties, there remains a dearth of such programs for radiology residency programs. At our institution, there has been a perceived decline in ultrasound scanning comfort and skill in trainees. The purpose of this project was to assess the utility and efficacy of a hands-on simulation-based ultrasound course for radiology residents.First-year radiology residents were enrolled in a 2-week simulation-based course for the instruction of hands-on ultrasound training. With the use of a customizable commercial simulation software platform, residents completed didactic modules, virtual simulations, and phantom scans for a 2-week rotation. A dedicated simulation center with scanning models and computer-based software was provided to all residents. Self-assessments and assignments provided benchmarks of performance. All radiology residents were surveyed at the start of the academic year to assess prior experience and comfort with ultrasound scanning. First-year residents were surveyed a second time upon course completion.Presurvey and postsurvey responses suggest that participation in the 2-week ultrasound scanning course contributed to an improvement in perceived scanning knowledge and comfort for participating residents. Based on our initial experience, the scanning curriculum presented here provides a comprehensive introductory course for first-year radiology residents both for ultrasound anatomy and for scanning technique. Continued education in hands-on ultrasound skills is a crucial factor in maintaining radiology's dominance in the modality.

Liver Ultrasound Elastography: Review of Techniques and Clinical Applications.

Chronic liver disease remains a substantial worldwide problem. Accurate estimation of liver fibrosis is crucial for determining the stage of the disease, assessing the patient's prognosis and predicting treatment response. Staging hepatic fibrosis has traditionally been done with liver biopsy but clinical practice has been changing, partly because liver biopsy has several disadvantages: it is invasive; it is associated with rare but serious complications; and it is prone to sampling error representing a tiny portion of the total liver volume. An increasing number of non-invasive liver fibrosis assessment have been developed. These include elastographic methods involving ultrasound (US) and magnetic resonance (MR) imaging. In this review article we discuss the different ultrasound-based elastography techniques, their clinical applications and various confounding factors in the assessment of hepatic fibrosis that may affect the accuracy of the measurements.

Thyroid Nodule Malignancy Risk Stratification Using a Convolutional Neural Network.

This study evaluates the performance of convolutional neural networks (CNNs) in risk stratifying the malignant potential of thyroid nodules alongside traditional methods such as American College of Radiology Thyroid Imaging Reporting and Data System (ACR TIRADS). The data set consisted of 651 pathology-proven thyroid nodules (500 benign, 151 malignant) from 571 patients collected at a single tertiary academic medical center. Each thyroid nodule consisted of two orthogonal views (sagittal and transverse) for a total of 1,302 grayscale images. A CNN classifier was developed to identify malignancy versus benign thyroid nodules, and a nested double cross validation scheme was applied to allow for both model parameter selection and for model accuracy evaluation. All thyroid nodules were classified according to ACR TIRADS criteria and were compared with their respective CNN-generated malignancy scores. The best performing model was the MobileNet CNN ensemble with an area under the curve of 0.86 (95% confidence interval, 0.83-0.90). Thyroid nodules within the highest and lowest CNN risk strata had malignancy rates of 81.4% and 5.9%, respectively. The rate of malignancy for ACR TIRADS ranged from 0% for TR1 nodules to 60% for TR5 nodules. Convolutional neural network malignancy scores correlated well with TIRADS levels, as malignancy scores ranged from 0.194 for TR1 nodules and 0.519 for TR5 nodules. Convolutional neural networks can be trained to generate accurate malignancy risk scores for thyroid nodules. These predictive models can aid in risk stratifying thyroid nodules alongside traditional professional guidelines such as TIRADS and can function as an adjunct tool for the radiologist when identifying those patients requiring further histopathologic workup.

2D shear wave elastography: measurement acquisition and reliability criteria in noninvasive assessment of liver fibrosis.

PURPOSE: The objective was to evaluate the accuracy of 2D shear wave elastography (SWE) in predicting stages of liver fibrosis using five individual versus grouped measurements and different reliability criteria. MATERIALS AND METHODS: This is a prospective study of 109 patients who underwent hepatic 2D SWE (Canon Aplio 500) prior to liver biopsy for varied indications. Liver fibrosis was staged using the METAVIR scoring system (F = 0-4). Propagation mapping was used to guide ten SWE measurements from the liver parenchyma: five individual measurements and five grouped measurements. IQR/median, SD/median, and SD/mean were examined as quality criteria for patient inclusion at various thresholds (IQR/median ≤ 0.15, 0.2, 0.3, 0.4, 0.5; SD/median ≤ 0.15, 0.2, 0.3; SD/mean ≤ 0.2, 0.3, 0.5). Threshold for clinically significant fibrosis (F ≥ 2) was determined with receiver operating characteristic (ROC) analysis. RESULTS: There was high agreement between individual and grouped measurements without statistically significant differences (intraclass correlation coefficient = 0.82; p = 0.26-0.96). When no quality criterion was used (n = 103), the optimal threshold was 11.3 kPa [AUROC 0.78, 95% CI (0.69, 0.88)] with sensitivity and specificity of 80% and 66%, respectively. All quality criteria were associated with equal or higher AUROC ranging from 0.78 to 0.87. IQR/median ≤ 0.5 (n = 88) achieved the highest sensitivity of 85% and only excluded a small subset of patients. The AUROC and specificity were 0.83 [95% CI (0.74, 0.92)] and 72%, respectively. SIGNIFICANCE: Quality criterion IQR/median ≤ 0.5 increases sensitivity and specificity in prediction of clinically significant liver fibrosis while excluding only a small subset of patients. Grouped measurements are comparable to individual measurements and may help increase procedural efficiency.

Image-Guided Cholecystostomy Tube Placement: Short- and Long-Term Outcomes of Transhepatic Versus Transperitoneal Placement.

OBJECTIVE: Image-guided percutaneous cholecystostomy may be performed by a transhepatic or transperitoneal approach. We compared the short- and long-term outcomes of percutaneous cholecystostomy related to route of catheter placement. MATERIALS AND METHODS: A retrospective observational study of image-guided percutaneous cholecystostomy was performed from 2004 to 2016. A search of the hospital's radiology information service was performed using the keywords "percutaneous cholecystostomy," "gallbladder drain," and "cholecystostomy tube" and the relevant Current Procedural Terminology codes. All search results were reviewed to identify the cohort of 373 patients who underwent initial percutaneous cholecystostomy catheter placement. Imaging was reviewed to determine the method and route of percutaneous cholecystostomy and complications. A chart review was performed to determine clinical outcomes. Differences were examined using a generalized linear model assuming a binary distribution and logit function. RESULTS: Percutaneous cholecystostomy catheter placement was performed using ultrasound guidance alone in 229 patients, ultrasound access with fluoroscopic guidance in 129 patients, CT guidance in 14 patients, and fluoroscopic guidance in one patient. The trocar technique was used for 183 patients, and the Seldinger technique was used for 190 patients. Two hundred eighteen percutaneous cholecystostomy catheters were placed via the transhepatic route, and 153 were placed via the transperitoneal route. The most common catheter sizes used were 8.5 French (n = 234) and 10 French (n = 124). No significant differences were observed between transperitoneal and transhepatic placement with regard to the frequency of pain, clogging, skin infection, bleeding, biloma, cholangitis, leakage, abscess, unplanned catheter removal, or need for replacement (p > 0.05). CONCLUSION: No evidence of a difference in outcomes was observed for transhepatic cholecystostomy tube placement over transperitoneal placement. The route that appears safer and less technically challenging should therefore be chosen.

Comparison of Performance Characteristics of American College of Radiology TI-RADS, Korean Society of Thyroid Radiology TIRADS, and American Thyroid Association Guidelines.

OBJECTIVE: The American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) provides guidelines to practitioners who interpret sonographic examinations of thyroid nodules. The purpose of this study is to compare the ACR TI-RADS system with two other well-established guidelines. MATERIALS AND METHODS: The ACR TI-RADS, the Korean Society of Thyroid Radiology (KSThR) Thyroid Imaging Reporting and Data System (TIRADS), and the American Thyroid Association guidelines were compared using 3422 thyroid nodules for which pathologic findings were available. The composition, echogenicity, margins, echogenic foci, and size of the nodules were assessed to determine whether a recommendation would be made for fine-needle aspiration or follow-up sonography when each system was used. The biopsy yield of malignant findings, the yield of follow-up, and the percentage of malignant and benign nodules that would be biopsied were determined for all nodules and for nodules 1 cm or larger. RESULTS: The percentage of nodules that could not be classified was 0%, 3.9%, and 13.9% for the ACR TI-RADS, KSThR TIRADS, and ATA guidelines, respectively. The biopsy yield of malignancy was 14.2%, 10.2%, and 10.0% for nodules assessed by the ACR TI-RADS, KSThR TIRADS, and ATA guidelines, respectively. The percentage of malignant nodules that were biopsied was 68.2%, 78.7%, and 75.9% for the ACR TI-RADS, the KSThR TIRADS, and the ATA guidelines, respectively, whereas the percentage of malignant nodules that would be either biopsied or followed was 89.2% for the ACR TI-RADS. The percentage of benign nodules that would be biopsied was 47.1%, 79.7%, and 78.1% for the ACR TI-RADS, the KSThR TIRADS, and the ATA guidelines, respectively. The percentage of benign nodules that would be either biopsied or followed was 65.2% for the ACR TI-RADS. CONCLUSION: The ACR TI-RADS performs well when compared with other well-established guidelines.

Does size matter? Kidney transplant donor size determines kidney function among living donors.

BACKGROUND: Kidney donor outcomes are gaining attention, particularly as donor eligibility criteria continue to expand. Kidney size, a useful predictor of recipient kidney function, also likely correlates with donor outcomes. Although donor evaluation includes donor kidney size measurements, the association between kidney size and outcomes are poorly defined. METHODS: We examined the relationship between kidney size (body surface area-adjusted total volume, cortical volume and length) and renal outcomes (post-operative recovery and longer-term kidney function) among 85 kidney donors using general linear models and time-to-chronic kidney disease data. RESULTS: Donors with the largest adjusted cortical volume were more likely to achieve an estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 over a median 24-month follow-up than those with smaller cortical volumes (P <0.001), had a shorter duration of renal recovery (1.3-2.2 versus 32.5 days) and started with a higher eGFR at pre-donation (107-110 versus 91 mL/min/1.73 m2) and immediately post-nephrectomy (∼63 versus 50-51 mL/min/1.73 m2). Similar findings were seen with adjusted total volume and length. CONCLUSIONS: Larger kidney donors were more likely to achieve an eGFR ≥60 mL/min/1.73 m2 with renal recovery over a shorter duration due to higher pre-donation and initial post-nephrectomy eGFRs.

ACR Appropriateness Criteria® Renal Transplant Dysfunction.

Renal transplantation is the treatment of choice in patients with end-stage renal disease because the 5-year survival rates range from 72% to 99%. Although graft survival has improved secondary to the introduction of newer immunosuppression drugs and the advancements in surgical technique, various complications still occur. Ultrasound is the first-line imaging modality for the evaluation of renal transplants in the immediate postoperative period and for long-term follow-up. In addition to depicting many of the potential complications of renal transplantation, ultrasound can also guide therapeutic interventions. Nuclear medicine studies, CT, and MRI are often helpful as complementary examinations for specific indications. Angiography remains the reference standard for vascular complications and is utilized to guide nonsurgical intervention. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of the ACR TI-RADS Committee.

Thyroid nodules are a frequent finding on neck sonography. Most nodules are benign; therefore, many nodules are biopsied to identify the small number that are malignant or require surgery for a definitive diagnosis. Since 2009, many professional societies and investigators have proposed ultrasound-based risk stratification systems to identify nodules that warrant biopsy or sonographic follow-up. Because some of these systems were founded on the BI-RADS® classification that is widely used in breast imaging, their authors chose to apply the acronym TI-RADS, for Thyroid Imaging, Reporting and Data System. In 2012, the ACR convened committees to (1) provide recommendations for reporting incidental thyroid nodules, (2) develop a set of standard terms (lexicon) for ultrasound reporting, and (3) propose a TI-RADS on the basis of the lexicon. The committees published the results of the first two efforts in 2015. In this article, the authors present the ACR TI-RADS Committee's recommendations, which provide guidance regarding management of thyroid nodules on the basis of their ultrasound appearance. The authors also describe the committee's future directions.

Multiinstitutional Analysis of Thyroid Nodule Risk Stratification Using the American College of Radiology Thyroid Imaging Reporting and Data System.

OBJECTIVE: Guidelines for managing thyroid nodules are highly dependent on risk stratification based on sonographic findings. The purpose of this study is to evaluate the risk stratification system used by the American College of Radiology Thyroid Imaging Reporting and Data System (TIRADS). MATERIALS AND METHODS: Patients with thyroid nodules who underwent sonography and fine-needle aspiration were enrolled in a multiinstitutional study. The sonographic nodule features evaluated in the study were composition, echogenicity, margins, and echogenic foci. Images were reviewed by two radiologists who were blinded to the results of cytologic analysis. Nodules were assigned points for each feature, and the points were totaled to determine the final TIRADS level (TR1-TR5). The risk of cancer associated with each point total and final TIRADS level was determined. RESULTS: A total of 3422 nodules, 352 of which were malignant, were studied. The risk of malignancy was closely associated with the composition, echogenicity, margins, and echogenic foci of the nodules (p < 0.0001, in all cases). An increased aggregate risk of nodule malignancy was noted as the TIRADS point level increased from 0 to 10 (p < 0.0001) and as the final TIRADS level increased from TR1 to TR5 (p < 0.0001). Of the 3422 nodules, 2948 (86.1%) had risk levels that were within 1% of the TIRADS risk thresholds. Of the 474 nodules that were more than 1% outside these thresholds, 88.0% (417/474) had a risk level that was below the TIRADS threshold. CONCLUSION: The aggregate risk of malignancy for nodules associated with each individual TIRADS point level (0-10) and each final TIRADS level (TR1-TR5) falls within the TIRADS risk stratification thresholds. A total of 85% of all nodules were within 1% of the specified TIRADS risk thresholds.

Optimizing modality selection for image-guided procedures: an analysis of the challenges to ultrasound guidance.

INTRODUCTION: Selection of the most appropriate modality for image guidance is essential for procedural success. We identified specific factors contributing to failure of ultrasound-guided procedures that were subsequently performed using CT guidance. MATERIALS AND METHODS: This single-center, retrospective study included 164 patients who underwent a CT-guided biopsy, aspiration/drainage, or ablation after initially having the same procedure attempted unsuccessfully with ultrasound guidance. Review of the procedure images, reports, biopsy results, and clinical follow-up was performed and the reasons for inability to perform the procedure with ultrasound guidance were recorded. Patient cross-sectional area and depth to target were calculated. Differences in area and depth were compared using general linear modeling. Depth as a predictor of an unfavorable body habitus designation was modeled using logistic regression. RESULTS: US guidance was successful in the vast majority of cases (97%). Of the 164 procedures, there were 92 (56%) biopsies, 63 (38%) aspirations/drainages, and 9 (5%) ablations. The most common reason for procedure failure was poor acoustic window (83/164, 51%). Other reasons included target lesion being poorly discerned from adjacent tissue (61/164, 37%), adjacent bowel gas (34/164, 21%), body habitus (27/164, 16%), and gas-containing collection (22/164, 13%). Within the biopsy subgroup, patients for whom body habitus was a limiting factor were found to have on average a larger cross-sectional area and lesion depth relative to patients whose body habitus was not a complicating factor (p < 0.0001 and p = 0.0009). CONCLUSION: Poor acoustic window was the most common reason for procedural failure with ultrasound guidance. In addition, as lesion depth increased, the odds that body habitus would limit the procedure also increased. If preliminary imaging suggests a limited sonographic window, particularly for deeper lesions, proceeding directly to CT guidance should be considered.