The potential of the Crystal Cam handheld gamma-camera for preoperative and intraoperative sentinel lymph node localization in early-stage oral cancer

Abstract

Purpose: Evaluating the Crystal Cam handheld gamma-camera for preoperative and intraoperative sentinel lymph node (SLN) localization in early-stage oral cancer.

Methods: The handheld gamma-camera was used complementary to conventional gamma-probe guidance for intraoperative SLN localization in 53 early-stage oral cancer patients undergoing SLN biopsy. In 36 of these patients, a blinded comparison was made between preoperative handheld gamma-camera and lymphoscintigraphy outcomes. Of those, the reliability for marking the SLN's location using both handheld gamma-camera and a ⁵⁷Co-penpoint marker was evaluated in 15 patients.

Results: In the entire cohort, the handheld gamma-camera preoperatively detected 116/122 (95%) of SLNs identified by lymphoscintigraphy. In those patients where the observer was blinded for lymphoscintigraphy (n = 36), 71/77 (92%) SLNs were correctly identified by handheld gamma-camera. Overlooked SLNs by handheld gamma-camera were mainly located near the injection site. The SLN's marked location by handheld gamma-camera and ⁵⁷Co-penpoint marker was considered accurate in 42/43 (98%) SLNs. The intraoperative use of the handheld gamma-camera led to the extirpation of 16 additional 'hot' lymph nodes in 14 patients, 4 of which harbored metastases, and prevented 2 patients (4%) from being erroneously staged negative for nodal metastasis. In those with follow-up ≥ 24 months or false-negative outcomes < 24 months following SLNB, a sensitivity of 82% and negative predictive value of 93% was obtained.

Conclusion: The Crystal Cam handheld gamma-camera offers reliable preoperative and intraoperative SLN localization and might reduce the risk of missing a malignant SLN during surgery. Detecting SLNs near the injection site by handheld gamma-camera remains challenging.

Keywords: CT; Gamma-camera; Lymphatic metastasis; Lymphoscintigraphy; Oral cancer; SPECT; Sentinel lymph node biopsy.

Fig. 1

Flowchart of study procedures. Dotted arrow represents patients (n = 15) who underwent both blinded assessment as well as cutaneous marking of the SLNs’ location by handheld gamma-camera and a ⁵⁷Co-penpoint marker. n number, SLN sentinel lymph node

Fig. 2

Comparison SPECT/CT (a, c) and Crystal Cam handheld gamma-camera images (b, d). Coronal plane of SPECT/CT (a) depicting injection site (*) and two SLNs located in level Ia and level Ib on the left side. Both SLNs (Ia, Ib) and injection site could be visualized within the field-of-view of the handheld gamma-camera (white square, a) (b). Two SLNs as identified by SPECT/CT (c) (sagittal plane; level IIa, III), also detected by handheld gamma-camera (IIa, III) (d)

Fig. 3

Crystal Cam handheld gamma-camera. a Equipped with a low-energy high-sensitivity (LEHS) collimator. b Equipped with a low-energy high-resolution (LEHR) collimator. c Connected to laptop with Crystal Imager software via USB

Fig. 4

a Cutaneous marking of the location of SLNs using Crystal Cam handheld gamma-camera and a ⁵⁷Co-penpoint marker. To simulate the definite surgical position, the patient is placed in supine position with head slightly extended and rotated to the opposite side. b Separate ⁵⁷Co-hotspot (⁵⁷Co) and ^99mTc-hotspot (^99mTc) within the handheld gamma-camera’s field-of-view. (c) Overlapping ⁵⁷Co-hotspot and ^99mTc-hotspot, indicating that the ⁵⁷Co-penpoint marker is positioned on the SLN’s location

Fig. 5

Intraoperative use of Crystal Cam handheld gamma-camera