SPECT/CT and sentinel node lymphoscintigraphy

Abstract

The use of single-photon emission computed tomography/computed tomography (SPECT/CT) for sentinel node (SN) detection has been evaluated in the majority of malignancies with predominantly superficial lymphatic drainage. In breast cancer and melanoma, important initial contributions of SPECT/CT were based on the anatomical localisation of SNs already visualised on planar images, the detection of additional SNs in aberrant basins, and the depiction of SNs in cases with no visualisation on planar images. However, more recently, the finding that SPECT/CT use is associated with a higher rate of SN detection, more metastatic SNs, and a higher rate of disease-free survival in large series of patients is leading SPECT/CT to be routinely performed in melanoma. The incorporation of SPECT/CT into the SN procedure in melanoma also appears to be cost effective and was significantly related to shorter operative times, shorter hospital stays, and fewer complications. In penile and vulvar cancer, the use of SPECT/CT has led to the detection of additional SNs. In oral cavity cancer and thyroid cancer, SPECT/CT not only appears to be useful for planar image interpretation but is also becoming an essential component of the SN procedure, providing surgeons with additional anatomical information. As regards malignancies with deep lymphatic drainage, SPECT/CT has been extensively validated in urological and gynaecological cancers. In these malignancies, SPECT/CT was able to localise SNs not only in the basins included in the area of extended pelvic lymph node dissection but also in aberrant locations. In gastrointestinal and lung malignancies, SPECT/CT has been used only incidentally. SPECT/CT must be considered complementary to planar lymphoscintigraphy for SN identification, and a combined interpretation of both modalities is necessary. With the improvement of the CT component, nuclear physicians today can also identify lymph nodes corresponding to radioactive SNs. This visual information is helpful for the intraoperative procedure and for post-excision assessment using portable devices.