Balanced Turbo Field Echo with Extended k-space Sampling: A Fast Technique for the Thoracic Ductography

Clinical impacts of magnetic resonance thoracic ductography on preventing postoperative chylothorax after thoracoscopic esophagectomy for esophageal cancer

PURPOSE

The study aimed to determine whether magnetic resonance thoracic ductography (MRTD) is useful for preventing injury to the thoracic duct (TD) during thoracoscopic esophagectomy and for reducing the incidence of postoperative chylothorax.

MATERIALS AND METHOD

A total of 389 patients underwent thoracoscopic esophagectomy between September 2009 and February 2019 in Tokai University Hospital. Of them, we evaluated 228 patients who underwent preoperative MRTD (MRTD group) using Adachi's classification and our novel classification (Tokai classification). Then, the clinicopathological factors of the MRTD group (n = 228) were compared with those of the non-MRTD group (n = 161), and comparative analyses were conducted after propensity score matching (PSM).

RESULTS

The TD could be visualized by MRTD in 228 patients. The MRTD findings were divided into 9 classifications including normal findings and abnormal TD findings (Adachi classification vs Tokai classification; 5.3% vs 16.2%). After PSM, both groups consisted of 128 patients. The rate of postoperative chylothorax after thoracoscopic esophagectomy was significantly lower in the MRTD group (0.8%) than in the non-MRTD group (6.3%) (p = 0.036). In the multivariate analysis for risk factors for chylothorax, the independent prognostic factors were preoperative therapy and the presence of MRTD.

CONCLUSIONS

This study revealed that MRTD was useful for preventing of chylothorax after thoracoscopic esophagectomy for esophageal cancer.

The Visibility of the Terminal Thoracic Duct Into the Venous System Using MR Thoracic Ductography with Balanced Turbo Field Echo Sequence

RATIONALE AND OBJECTIVES

Magnetic resonance thoracic ductography (MRTD) with balanced turbo field echo (bTFE) can visualize both the thoracic duct and its surrounding vessels. This study aimed to investigate the visibility of the terminal thoracic duct into the venous system in the subclavian region using MRTD with bTFE.

MATERIALS AND METHODS

MRTD was performed with bTFE as a preoperative workup comprising respiratory gating on a 1.5-T magnetic resonance system for patients with esophageal cancer. The portion and the number of terminal thoracic ducts into the venous system and preterminal branching in the left subclavian region were assessed using MRTD in 132 patients. The confidence level of the visibility using MRTD was also evaluated.

RESULTS

The most frequent terminal portion of the thoracic duct was the jugulovenous angle (92 patients, 69.7%), followed by the subclavian vein (27 patients, 20.5%) and the internal jugular vein (8 patients, 6.1%). Four patients also exhibited double entry of the thoracic duct into the venous system. The preterminal branching was single in 96 patients (72.7%) and multiple in 36 patients (27.3%). The confidence level of the visibility of the thoracic duct using MRTD was absolutely certain in 112 patients (84.8%) and was somewhat certain in 20 patients (15.2%).

CONCLUSIONS

MRTD with bTFE is a robust imaging modality to visualize the terminal portion of the thoracic duct into the venous system in the subclavian region.

Magnetic resonance thoracic ductography assessment of serial changes in the thoracic duct after the intake of a fatty meal

The thoracic duct, a terminal lymph vessel, is thought to dilate after the intake of a fatty meal. However, this physiological change has not been well explored in vivo. Therefore, the present study aimed to assess serial changes in the thoracic duct after the intake of a fatty meal using magnetic resonance thoracic ductography (MRTD). Eight healthy volunteers were subjected to one MRTD scan before a fatty meal and eight serial MRTD scans every hour thereafter. The cross-sectional areas of the thoracic duct were estimated using MRTD measurements of the diameters of the thoracic duct at the upper edge of the aortic arch, the tracheal bifurcation, the mid-point between the tracheal bifurcation and the left part of the diaphragm and the left part of the diaphragm. The change-rates in these areas were calculated before and after the fatty meal intake, and the maximal change-rate and timing of its achievement were determined for each subject. The summed change-rates in the four portions of the thoracic duct ranged from -40.1 to 81.3%, with maximal change-rates for each subject ranging from 22.8 to 81.3% (mean, 50.4%). Although individual variations were observed, most subjects (88.9%) exhibited a maximal change-rate at 4-6 h after meal intake, with subsequent decreases at 7-8 h. In conclusion, MRTD revealed a tendency toward thoracic duct enlargement at 4-6 h after the intake of a fatty meal, followed by contraction.