SPECT/CT detects metastatic nodes in melanoma

By medwireNews Reporters

The preoperative use of single-photon emission CT (CT) plus CT (SPECT/CT) imaging improves the detection of metastatic lymph nodes over standard lymphoscintigraphy, research shows.

In addition, SPECT/CT-aided sentinel lymph node (SLN) excision results in an increase in disease-free survival among patients with lymph node-negative melanoma, demonstrate results published in the Journal of the American Medical Association.

"The preoperative visualization of SLN with SPECT/CT is technically feasible and facilitates the detection of additional positive SLNs," report researcher Joachim Klode (University School of Medicine Essen-Duisburg, Germany) and colleagues.

Significantly more SLNs per patient were detected in the 149 patients in the SPECT/CT cohort than in the 254 patients who underwent standard preoperative lymphoscintigraphy (2.40 vs 1.87).

When SLN excisions were performed using the 3D SPECT/CT, 0.34 positive lymph nodes per patient were detected. By contrast, 0.21 positive lymph nodes were detected when standard SLN excisions were performed, a statistically significant difference.

At 4 years, disease-free survival in the SPECT/CT-aided treatment arm was significantly higher at 93.9% compared with 79.2% in the standard SLN excision arm. The use of SPECT/CT was significantly predictive of disease-free survival in multivariate analysis, with a significantly hazard ratio of 4.1.

Patients in both treatment arms were similar in terms of age, tumor depth, and ulceration of the primary tumor. In terms of tumor location, 43.4% had tumors in the torso, 41.9% had tumors in the extremities, and 9.4% had tumors in the head or neck.

Surgeons were able to excise SLNs for tumors in the head or neck in 23.5% of patients who underwent preoperative SPECT/CT imaging, compared with just 2.0% of patients treated with the standard procedure.

The SPECT/CT versus the standard approach also allowed for the detection of sentinel lymph nodes in obese patients.

The reported false-positive rate in the SPECT/CT treatment arm was 6.8% compared with 23.8% in the standard-treatment arm.

Among the patients undergoing SPECT/CT, alterations to the surgical procedure were made as a result of the 3D imaging in 22.1% of cases.

"The use of this technique offers the physician the preoperative possibility of determining the exact location and visualization of the SNL," write Klode and colleagues.

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