Evaluation of Motion Artifact Correction Technique for Cone-Beam Computed Tomography Image Considering Blood Vessel Geometry.

Background: In this study, we present a quantitative method to evaluate the motion artifact correction (MAC) technique through the morphological analysis of blood vessels in the images before and after MAC. Methods: Cone-beam computed tomography (CBCT) scans of 37 patients who underwent transcatheter chemoembolization were obtained, and images were reconstructed with and without the MAC technique. First, two interventional radiologists selected the blood vessels corrected by MAC. We devised a motion-corrected index (MCI) metric that analyzed the morphology of blood vessels in 3D space using information on the centerline of blood vessels, and the blood vessels selected by the interventional radiologists were quantitatively evaluated using MCI. In addition, these blood vessels were qualitatively evaluated by two interventional radiologists. To validate the effectiveness of the devised MCI, we compared the MCI values in a blood vessel corrected by MAC and one non-corrected by MAC. Results: The visual evaluation revealed that motion correction was found in the images of 23 of 37 patients (62.2%), and a performance evaluation of MAC was performed with 54 blood vessels in 23 patients. The visual grading analysis score was 1.56 ± 0.57 (radiologist 1) and 1.56 ± 0.63 (radiologist 2), and the proposed MCI was 0.67 ± 0.11, indicating that the vascular morphology was well corrected by the MAC. Conclusions: We verified that our proposed method is useful for evaluating the MAC technique of CBCT, and the MAC technique can correct the blood vessels distorted by the patient's movement and respiration.

Thoracic duct embolization in treating postoperative chylothorax: does bail-out retrograde access improve outcomes?

OBJECTIVES: To evaluate clinical outcomes of thoracic duct embolization (TDE) for the management of postoperative chylothorax with the aid of the bail-out retrograde approach for thoracic duct cannulation (TDC). MATERIALS AND METHODS: Forty-five patients with postoperative chylothorax underwent Lipiodol lymphangiography (LLG) between February 2016 and November 2019. If targetable central lymphatic vessels were identified in LLG, TDC, a prerequisite for TDE, was attempted. While the conventional antegrade transabdominal approach was the standard TDC method, the retrograde approach was applied as a bail-out method. Embolization, the last step of TDE, was performed after confirming leakages in the trans-TDC catheter lymphangiography. Technical and clinical success rates were determined retrospectively. RESULTS: TDC was attempted in 40 among 45 patients based on LLG findings. The technical success rate of TDC with the conventional antegrade approach was 78% (31/40). In addition, six more patients were cannulated using the bail-out retrograde approach, which raised the technical success rate to 93% (37/40). While 35 patients underwent embolization (TDE group), ten patients did not (non-TDE group) for the following reasons: (1) lack of targetable lymphatics for TDC in LLG (n = 5), (2) technical failure of TDC (n = 3), and (3) lack of discernible leakages in the transcatheter lymphangiography (n = 2). The clinical success of the TDE group was 89% (31/35), compared with 50% (5/10) of the non-TDE group. One major procedure-related complication was bile peritonitis caused by the needle passage of the distended gallbladder. CONCLUSIONS: Bail-out retrograde approach for TDC could improve the overall technical success of TDC significantly. KEY POINTS: • Bail-out retrograde thoracic duct access may improve the overall technical success of thoracic duct access, thus improving the clinical success of thoracic duct embolization.

Novel interventional radiological management for lymphatic leakages after gynecologic surgery: lymphangiography and embolization.

Post-operative lymphatic leakage is a common complication of a radical gynecologic surgery involving aggressive lymph node dissection. Its manifestation varies from asymptomatic lymphoceles to life-threatening chylous ascites. In the past, nuclear medicine lymphoscintigraphy was the sole imaging modality for the confirmation of the leakage, of which application is limited due to its poor spatial resolution. While a conservative treatment with percutaneous drainage was the mainstream treatment method, surgical exploration was the last resort for the recalcitrant leakages. Recently, there have been a series of innovations in the field of interventional radiology, including intranodal Lipiodol® lymphangiography, dynamic magnetic resonance (MR) lymphangiography, lymphatic embolization, and mesenteric lymph node lymphangiography. Intranodal Lipiodol® lymphangiography provides very reliable and secure access to the lymphatic system, while requiring only fundamental skills and equipment available to all interventional radiologists. Besides, Lipiodol® is being received a spotlight for its potential therapeutic effects on refractory lymphatic leakage. Dynamic MR lymphangiography plays a vital role in the diagnosis and management of non-traumatic lymphatic diseases, as well as in the post-operative lymphatic leakage with its superior contrast, spatial and temporal resolution. Lymphatic embolization is a technique of using N-BCA glue, a liquid embolic agent, for lymphatic leakages. It can be further described as lymphopseudoaneurysm (LPA) embolization or lymph node embolization, according to which structure is being embolized. Lymphatic embolization opened a new realm of possibilities in the field of interventional lymphology, resulting in the development of treatment approaches for chylous ascites and lymphoceles. Mesenteric lymph node lymphangiography offers the opacification of the upstream mesenteric chylous lymphatic system and can detect lymphatic leakage from the intestinal trunk or the more proximal parts of the mesenteric lymphatic system. With the advent of these latest interventional radiological techniques, more comprehensive approaches to the management of recalcitrant post-operative lymphatic leakages have been enabled.

Interventional Radiology Treatment for Postoperative Chylothorax.

Postoperative chylothorax is a rare occurrence after various thoracic surgical procedures, but it poses a substantial risk of morbidity and mortality. Thoracic duct embolization (TDE) is currently deemed the optimal treatment due to its safety and efficacy. This review offers an introduction to interventional options in this setting, detailing the steps of TDE for the edification of those engaged in postoperative care.

Quantification of tricuspid regurgitation using two-dimensional velocity encoding cine: optimal plane and reproducibility.

To determine the optimal plane of two-dimensional velocity-encoding cine (VENC) magnetic resonance (MR) imaging at the tricuspid annulus for quantification of tricuspid regurgitation (TR) and to assess the reproducibility of VENC tricuspid flow measurements. We conducted a retrospective review of MR images of 25 consecutive patients (M:F = 8:17; mean age, 58.5 ± 10.5 years) with TR. VENC was performed twice orthogonal to the tricuspid annulus plane during the end-diastolic (ED) and end-systolic (ES) phases. The TR fraction was quantified at each plane as retrograde flow/antegrade flow and additionally as retrograde flow of the ED plane/antegrade flow of the ES plane (combined plane method). The conventional method to determine the TR amount [right ventricular stroke volume (RVSV)-pulmonary antegrade flow] and TR fraction (TR amount/RVSV) was used as the reference standard. There were no differences between TR amount and retrograde flow of the ED plane (65.3 ± 43.4 vs. 70.5 ± 36.1 ml, P = 0.361) between the RVSV and the antegrade flow of the ES phase (124.2 ± 46.1 vs. 128.0 ± 45.0 ml, P = 0.612) or in TR fraction between the conventional and combined plane methods (48.8 ± 19.2 vs. 56.3 ± 24.3 %, P = 0.08). The retrograde flow of the ED phase was best correlated with TR amount [intraclass correlation coefficient (ICC) = 0.859] and antegrade flow of ES with RVSV (ICC = 0.808). The TR fraction of the combined plane method was best correlated with the conventional method (ICC = 0.694). Interobserver agreement of VENC flow measurements was excellent (ICC, 0.939-0.993). The optimal method for quantification of TR using tricuspid annular VENC was the combined plane method, which divides the retrograde flow of the ED plane by the antegrade flow of the ES plane. Tricuspid flow measurements using VENC showed excellent reproducibility.