Utility of planning MRI in percutaneous thoracic duct embolization for chylothorax.

PURPOSE: Percutaneous thoracic duct embolization (TDE) is an accepted treatment for leaks of the central lymphatic ducts. In this study, we correlate the imaging findings on pre-procedural MRI lymphangiography with findings on conventional lymphangiography, and with operator ability to perform a technically successful TDE. The aim was to examine whether MRI is a good screening mechanism to support an invasive procedure in strong candidates, and avert one in poor candidates. MATERIALS AND METHODS: MRI and conventional lymphangiograms of 96 patients (62 male and 34 female; mean age 63 ± 11 years, range 29-92 years) were retrospectively reviewed. The diameter and level of the best target for access were assessed for each study. Technical success rates were evaluated with respect to presence of a cisterna chyli, target duct size, and target level concordance. RESULTS: Presence of a cisterna chyli on MRI significantly increased the likelihood of a successful TDE (68% vs. 42%, p = 0.03). Presence of a duct 4 mm or larger, by either modality, significantly improved the chance of successful TDE (for MRI, 65% vs. 41%, p = 0.04; for lymphangiography, 70% vs. 44%, p = 0.03). MRI was not helpful for localizing a lymphatic target, as less than half were seen within one and one-half vertebrae of the predicted level. There was a weak correlation (Pearson coefficient = +0.30) between duct size as measured on the two modalities. 95% of those without an identifiable target on MRI had a viable target on lymphangiography, and successful TDE was performed in 47% of those patients. CONCLUSIONS: Identification of a cisterna chyli and/or 4 mm or greater target on pre-procedural MRI indicated higher likelihood of technically successful TDE. MRI did not help predict unsuccessful TDE procedures. Better target level concordance was not associated with improved technical outcomes.

Hybrid Interactive and Didactic Teaching Format Improves Resident Retention and Attention Compared to Traditional Lectures.

PURPOSE: To compare the traditional lecture to a hybrid interactive and didactic teaching format with regards to radiology resident short- and long-term retention, as well as attention. MATERIALS AND METHODS: The tested hybrid format consists of a 30-minute didactic lecture followed by 30 minutes of interactive cases based on material from the lecture portion. Faculty members were randomly selected to give a 60-minute lecture or a hybrid presentation. To assess short- and long-term retention, a test developed from the presenter's slides was sent to all residents approximately 15 minutes after each presentation, and again approximately 3 months later. The presenters were blinded to the survey questions. Attention was assessed by comparing the proportion of questions answered correctly from each quarter of the presentation. Equality in difficulty of questions was validated across teaching methods. RESULTS: For 6 hybrid presentations, 106 and 60 retention tests were submitted, answering 848 and 480 short- and long-term survey questions, respectively. For 6 lectures, 91 and 55 retention tests were submitted, answering 728 and 440 short- and long-term survey questions, respectively. Short-term retention was 75.7% (640/848) for hybrid presentations, versus 63.2% (460/728) for lectures (p < 0.0001). Long-term retention was 59.4% (285/480) for hybrid presentations, versus 49.3% (217/440) for lectures (p = 0.002). Regarding attention, 61.6% (554/600) of questions from the first 3 quarters of traditional lectures were answered correctly versus 49.3% (148/300) of final quarter questions (p = 0.0003). No significant drop-off was noted for hybrid presentations. CONCLUSION: A hybrid interactive and didactic teaching format for radiology residents demonstrates better short-term retention, long-term retention, and attention when compared to traditional lectures.

A Simulation Paradigm for Evaluation of Subtle Liver Lesions at Pediatric CT: Performance and Confidence.

Purpose: To create and validate a systematic observer performance platform for evaluation of simulated liver lesions at pediatric CT and to test this paradigm to measure the effect of radiation dose reduction on detection performance and reader confidence. Materials and Methods: Thirty normal pediatric (from patients aged 0-10 years) contrast material-enhanced, de-identified abdominal CT scans obtained from July 1, 2012, through July 1, 2016, were retrospectively collected from the clinical database. The study was exempt from institutional review board approval. Zero to three simulated, low-contrast liver lesions (≤6 mm) were digitally inserted by using software, and noise was added to simulate reductions in volume CT dose index (representing radiation dose estimation) of 25% and 50%. Pediatric, abdominal, and resident radiologists (three of each) reviewed 90 data sets in three sessions using an online interface, marking each lesion location and rating confidence (scale, 0-100). Statistical analysis was performed by using software. Results: Mixed-effects models revealed a significant decrease in detection sensitivity as radiation dose decreased (P < .001). The mean confidence of the full-dose and 25% dose reduction examinations was significantly higher than that of the 50% dose reduction examinations (P = .011 and .012, respectively) but not different from one another (P = .866). Dose was not a significant predictor of time to complete each case, and subspecialty was not a significant predictor of sensitivity or false-positive results. Conclusion: Sensitivity for lesion detection significantly decreased as dose decreased; however, confidence did not change between the full-dose and 25% reduced-dose scans. This suggests that readers are unaware of this decrease in performance, which should be accounted for in clinical dose reduction efforts.Keywords: Abdomen/GI, CT, Liver, Observer Performance, Pediatrics, Perception Image© RSNA, 2019.

MRI of the Central Lymphatic System: Indications, Imaging Technique, and Pre-Procedural Planning.

Magnetic resonance imaging is increasingly being used to evaluate the lymphatic system. Advances in magnetic resonance (MR) software and hardware allow improved visualization of lymph nodes and lymphatic vessels. We describe how MR lymphangiography can be used to diagnose central lymphatic system anatomy and pathology, which can be used for diagnostic purposes or for pre-procedural planning.

Thoracic duct embolization and disruption for treatment of chylous effusions: experience with 105 patients.

PURPOSE: To review the indications, technical approach, and clinical outcomes of thoracic duct embolization (TDE) and thoracic duct disruption (TDD) in patients with symptomatic chylous effusions. MATERIALS AND METHODS: A total of 105 patients who underwent 120 consecutive TDE/TDD procedures were retrospectively reviewed. Data including cause of effusion, procedural technique, and pre- and postprocedural effusion volume were analyzed. Technical and clinical success were evaluated for each procedure, with technical success defined as successful interruption of the thoracic duct by embolization or needle disruption and clinical success defined as resolution of effusion without surgical intervention. RESULTS: The technical success rate was 79% (95 of 120); 53 TDEs were performed, resulting in a 72% clinical success rate (n = 38), whereas 42 TDDs showed a 55% clinical success rate (n = 23; P = .13). Procedures to treat postpneumonectomy chylous effusions had a success rate of 82% (14 of 17), compared with 47% (nine of 19) in postpleurectomy subjects (P < .05). Clinically successful cases had lower 24-, 48-, and 72-hour postprocedural effusion volumes versus clinically unsuccessful cases (P < .05), as well as greater rates of reduction in effusion volume at these time points (P < .05). Clinical success rate in subjects with traumatic effusions was higher than in subjects with nontraumatic effusions (62% [60 of 97] vs 13% [one of eight]; P < .05), and 6.7% of subjects (n = 7) experienced minor complications. CONCLUSIONS: TDE and TDD are safe and effective minimally invasive treatments for traumatic thoracic duct injuries. In the present series, factors affecting procedural success included etiology of effusion, postprocedural effusion volume, and rate of postprocedural effusion volume reduction.

Safety and utility of transjugular liver biopsy in hematopoietic stem cell transplant recipients.

PURPOSE: Hematopoietic stem cell transplant (HSCT) recipients are at high risk in the setting of percutaneous liver biopsy as a result of comorbid coagulopathy and ascites, and are commonly referred to undergo transjugular liver biopsy. The present study was performed to assess the safety and utility of transjugular liver biopsy in HSCT recipients and to analyze the correlation between corrected hepatic sinusoidal pressure gradient (CHSPG) and pathologic diagnoses. MATERIALS AND METHODS: Data from reports of transjugular liver biopsy procedures, pathology reports, and laboratory values of 141 consecutive HSCT recipients who underwent transjugular liver biopsy with pressure measurement between January 2005 and August 2011 in a single institution were retrospectively reviewed and analyzed. RESULTS: A total of 166 biopsy procedures were performed in 141 patients. Technical success rate was 98.8%. Biopsy was diagnostic in 95.7% of patients. There were three major complications (1.8%), including one death. CHSPG in patients with venoocclusive disease (VOD) was significantly higher (P<.001) than in those without VOD (16.2 mm Hg±9.2 vs 5.6 mm Hg±3.7). A CHSPG of 10 mm Hg or higher was 90.8% specific and 77.3% sensitive for VOD. CONCLUSIONS: The present data show that transjugular liver biopsy is a relatively safe procedure that provides important information for the clinical management of patients with HSCT. Measurement of CHSPG during the procedure can support the diagnosis of VOD.