Three-dimensional lymphoscintigraphy using SPECT/CT and 123I-BMIPP for the preoperative detection of anatomical anomalies of the thoracic duct.

Purpose: Orally administered I-labeled 15-(4-iodophenyl)-3(R,S)-methylpentadecanoic acid (BMIPP), a fatty acid analog, is absorbed from the intestine and ascends to the venous angle through the thoracic duct (TD). The objective of this study was to evaluate the clinical feasibility of 3-dimensional (3D) TD scintigraphy using SPECT/CT and BMIPP for the detection of anatomical anomalies of TD.

Patients And Methods: This study included 35 consecutive patients with esophageal cancer who underwent tumor resection after TD scintigraphy. For scintigraphy, 111 MBq of BMIPP was orally administered, and static images and SPECT/CT images were obtained. On the basis of the SPECT/CT fusion images, TD was divided into the following 4 segments: cervical, upper thoracic, middle thoracic, and lower thoracic. The TD visualization was categorized into 5 grades, from grade 1 (poor) to 5 (excellent). In addition, the diagnostic accuracy of 3D TD scintigraphy for the detection of anatomical anomalies of TD was calculated using the intraoperative finding as a criterion standard.

Results: The TD visualization grades for the cervical, upper, middle, and lower thoracic segments were 4.4 ± 0.6, 3.7 ± 1.0, 3.1 ± 0.8, and 2.1 ± 0.9, respectively. The TD scintigraphy demonstrated an uncommon accumulation including that in the right- or bilateral-sided mediastinum or venous angle in 6 (17%) of the 35 patients. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of 3D TD scintigraphy for the detection of anatomical anomalies of TD were 0.75, 0.90, 0.5, 0.97, and 0.89, respectively.

Conclusions: Three-dimensional TD scintigraphy by BMIPP is a simple and minimally invasive method for imaging the anatomical configuration of the TD and for detecting any anatomical anomalies, except in the lower thoracic segment.