MR lymphography with superparamagnetic iron oxide for sentinel lymph node mapping of N0 early oral cancer: A pilot study

Objectives: The purpose of this pilot study was to evaluate the usefulness of magnetic resonance lymphography (MRL) with superparamagnetic iron oxide (SPIO) in sentinel lymph node (SLN) mapping of clinically N0 early oral cancer, and to conduct a comparative study of this MRL with CT lymphography (CTL). Methods: CTL and MRL were performed for SLN mapping before surgery for 20 patients with clinically N0 early oral cancer. The detection rate, number, and location of SLNs in CTL and MRL were evaluated. Furthermore, optimal scanning/imaging timing in MRL was examined. Results: SLNs were detected by CTL in 18 (90%) patients, and the total and mean number of SLN were 35 and 1.8, respectively. All SLNs could be detected 2 min and 3.5–5 min after contrast medium injection. In all patients, SLNs were detected by MRL at 10 min after SPIO injection, and the total and mean number of SLN was 53 and 2.7, respectively. MRL at 30 min after the injection showed additional 18 secondary lymph nodes. Conclusion: MRL with SPIO is safe and useful imaging for the detection of SLNs in clinically N0 early oral cancer, and the optimal imaging timing is 10 min after SPIO injection.

Patients Radiation Risks from Computed Tomography Lymphography

Objectives: This study aims to first measure patient doses during computed tomography (CT) chest, abdomen, and extremities procedures for evaluation lymphedema, and second to estimate the radiation dose-related risks during the procedures. Material and Methods: Radiation effective doses from CT lymphography procedures quantified using CT machines from different vendors. After the calibration of CT systems, the data collected for a total of 28 CT lymphography procedures. Effective and organ doses extrapolated using national radiological protection software based on Monte Carlo simulation. Results: The mean patient doses for chest and abdomen procedures in term of CTDIvol (mGy) and DLP (mGy.cm) are 10.0 ± 3 and 425 ± 222 and 24 ± 12 and 1118 ± 812 for CT 128 and CT 16 slice, respectively. The mean DLP (mGy.cm) for extremities was 320 ± 140 and 424 ± 212 for CT 128 and CT 16 slice, in that order. Conclusion: Patients’ dose showed significant differences due to variation in the scan length and clinical indication. Organs lay in the primary beam received high radiation doses especially in the chest region which increases the probability of radiation-induced cancer. The current patient’s doses are higher compared to the previous studies.

Perirectal injection of imaging materials for computed tomographic lymphography and near infrared fluorescent thoracoscopy in cats

For the treatment of chylothorax, the most common procedure is a thoracic duct ligation; however, recurrence of the issue is often common, generally due to the incomplete ligation of all thoracic duct tributaries. Therefore, accurate localisation of the thoracic duct tributaries is required to determine the ligation sites in each patient. The concept of the perirectal injection of the imaging materials, which provides a simple and minimally invasive approach, is investigated for computed tomographic (CT) lymphography and near infrared fluorescent thoracoscopy in cats. Three clinically healthy cats were used for the CT lymphography, and two clinically healthy cats were used for the near infrared fluorescent thoracoscopy. Iodine contrast agent for the CT or indocyanine green for the thoracoscopy was injected subcutaneously into the peri-anal tissue. The injection site was massaged for 5 min post-injection. However, in the indirect injection of the imaging materials, in three iohexol-administered cats, the abdominal lymphatics, cisterna chyle, and thoracic duct could be depicted by the CT lymphography; and in both indocyanine green-administered cats, the thoracic duct was depicted running alongside the aorta by the near infrared fluorescent thoracoscopy. The ideal imaging procedure for the thoracic duct ligation involves the pre-operative CT lymphography of the entire pathway of the lymphatic vessels in advance, followed by the direct visualisation using a thoracoscopy. A combined CT lymphography and thoracoscopy could be a reliable method for successful surgeries. Crucially, the subcutaneous peri-anal injection of a contrast/dye provides a simple and minimally invasive method for the pre-operative and intra-operative depiction of the lymphatic pathways.