Dominique N. V. Donders

Objectives: To assess the efficacy of magnetic resonance (MR) lymphography with gadobutrol contrast for sentinel lymph node (SLN) mapping in early-stage oral squamous cell carcinoma (OSCC). Methods: This pilot study compared the identification of SLNs by MR lymphography using a gadolinium-based contrast agent (gadobutrol) to conventional [^99mTc]Tc-nanocolloid lymphoscintigraphy (including single-photon emission computed tomography/computed tomography (SPECT/CT)) in 10 early-stage OSCC patients undergoing SLN biopsy. The patients initially underwent conventional lymphoscintigraphy following the peritumoral administration of indocyanine green [^99mTc]Tc-nanocolloid (120 megabecquerel; ~0.5 mL). Subsequently, 0.5–1.0 mL gadobutrol was peritumorally injected, and MR imaging was acquired for 30 min. The following day, the identified SLNs were harvested and subjected to a histopathological assessment. The MR lymphography and [^99mTc]Tc-nanocolloid lymphoscintigraphy results were evaluated and compared with respect to those of the SLN identification. The reference standard consisted of a histopathological evaluation of the harvested SLNs, complementary neck dissection specimens, and follow-up data. Results: The MR lymphography detected 16 out of 27 SLNs identified by [^99mTc]Tc-nanocolloid lymphoscintigraphy, revealing an additional SLN that did not harbor metastasis. MR lymphography failed to identify any SLNs in one patient. Of the seven histopathologically positive SLNs detected by [^99mTc]Tc-nanocolloid lymphoscintigraphy, three were identified by MR lymphography. All patients remained disease-free after a median follow-up of 16 months. Compared to [^99mTc]Tc-nanocolloid lymphoscintigraphy, MR lymphography using gadobutrol achieved an SLN identification rate of 59%, a sensitivity of 75%, and a negative predictive value of 86%. Conclusions: MR lymphography using gadobutrol demonstrates limited reliability for SLN mapping in early-stage OSCC.

This study evaluated sentinel lymph node (SLN) identification with CT lymphography (CTL) following peritumoral administration of Lipiodol^® relative to conventional ^99mTc-nanocolloid lymphoscintigraphy (including SPECT/CT) in 10 early-stage oral cancer patients undergoing SLN biopsy. Patients first underwent early dynamic and static scintigraphy after peritumoral administration of ^99mTc-nanocolloid. Subsequently, Lipiodol^® was administered at the same injection sites, followed by fluoroscopy and CT acquisition. Finally, late scintigraphy and SPECT/CT were conducted, enabling the fusion of late CTL and SPECT imaging. The next day, designated SLNs were harvested, radiographically examined for Lipiodol^® uptake and histopathologically assessed. Corresponding images of CT, ^99mTc-nanocolloid lymphoscintigraphy and SPECT/late CTL fusion were evaluated. ^99mTc-nanocolloid lymphoscintigraphy identified 21 SLNs, of which 7 were identified with CTL (33%). CTL identified no additional SLNs and failed to identify any SLNs in four patients (40%). Out of six histopathologically positive SLNs, two were identified by CTL (33%). Radiographic examination confirmed Lipiodol^® uptake in seven harvested SLNs (24%), of which five were depicted by CTL. CTL using Lipiodol^® reached a sensitivity of 50% and a negative predictive value (NPV) of 75% (median follow-up: 12.3 months). These results suggest that CTL using Lipiodol^® is not a reliable technique for SLN mapping in early-stage oral cancer.

Purpose To compare sentinel lymph node (SLN) identification using [⁶⁸Ga]Ga-tilmanocept PET/CT lymphoscintigraphy to [^99mTc]Tc-tilmanocept lymphoscintigraphy (including SPECT/CT) in early-stage oral cancer. Furthermore, to assess whether reliable intraoperative SLN localization can be performed with a conventional portable gamma-probe using [^99mTc]Tc-tilmanocept without the interference of [⁶⁸Ga]Ga-tilmanocept in these patients. Methods This prospective within-patient comparison pilot study evaluated SLN identification by [⁶⁸Ga]Ga-tilmanocept PET/CT lymphoscintigraphy compared to conventional lymphoscintigraphy using [^99mTc]Tc-tilmanocept (~ 74 MBq) in 10 early-stage oral cancer patients scheduled for SLN biopsy. After conventional [^99mTc]Tc-tilmanocept lymphoscintigraphy, patients underwent peritumoral administration of [⁶⁸Ga]Ga-tilmanocept (~ 10 MBq) followed by PET/CT acquisition initiated 15 min after injection. Intraoperative SLN localization was performed under conventional portable gamma-probe guidance the next day; the location of harvested SLNs was correlated to both lymphoscintigraphic images in each patient. Results A total of 24 SLNs were identified by [^99mTc]Tc-tilmanocept lymphoscintigraphy, all except one were also identified by [⁶⁸Ga]Ga-tilmanocept PET/CT lymphoscintigraphy. [⁶⁸Ga]Ga-tilmanocept PET/CT lymphoscintigraphy identified 4 additional SLNs near the injection site, of which two harbored metastases. Lymphatic vessels transporting [⁶⁸Ga]Ga-tilmanocept were identified by PET/CT lymphoscintigraphy in 80% of patients, while draining lymphatic vessels were visualized by [^99mTc]Tc-tilmanocept lymphoscintigraphy in 20% of patients. Of the 33 SLNs identified by [⁶⁸Ga]Ga-tilmanocept PET/CT lymphoscintigraphy, 30 (91%) were intraoperatively localized under conventional gamma-probe guidance. Conclusion [⁶⁸Ga]Ga-tilmanocept PET/CT lymphoscintigraphy provided more accurate identification of SLNs and improved visualization of lymphatic vessels compared to [^99mTc]Tc-tilmanocept lymphoscintigraphy. When combined with peritumoral administration of [^99mTc]Tc-tilmanocept, SLNs detected by [⁶⁸Ga]Ga-tilmanocept PET/CT lymphoscintigraphy can be reliably localized during surgery under conventional gamma-probe guidance.