Fusion of freehand SPECT and ultrasound: First experience in preoperative localization of sentinel lymph nodes.
OBJECTIVE
Radioguided sentinel lymph node biopsy (SLNB) is the standard of care in breast cancer and melanoma. Additional preoperative Single-photon emission computed tomography (SPECT/CT) for improved anatomical co-registration of the SLNs causes additional radiation exposure and is time-consuming and expensive. The aim of this prospective study was to evaluate a novel approach involving real-time fusion of freehand SPECT (fhSPECT) and ultrasound (US) for anatomical co-registration of SLNs.


METHODS
From February 2015 to February 2016, 153 patients were included in this prospective study. All patients underwent lymphoscintigraphy according to practical guidelines and 151 (118 cases of breast cancer, 30 cutaneous malignancies, and three cases of vulvar cancer) of the 153 patients were additionally investigated with fhSPECT-US. FhSPECT connected to a hand-held gamma detector generates three-dimensional images of the radioactivity distribution in the scanned area. For co-registration and real-time fusion of fhSPECT and subsequently performed US, an infrared stereo tracking system was used.


RESULTS
In all patients an SLN was found on lymphoscintigraphy, and the fhSPECT detected corresponding hotspots in all but one patient. In 72 % of patients and 73 % of lymph node basins, real-time anatomical co-registration with US was feasible. The rate of success in achieving good co-registration increased from 60 to 75 % after training by a radiologist specialized in breast imaging. A higher co-registration rate (78 %) was observed in patients with only one SLN than in those with two SLNs (68 %) or three or more SLNs (0 %).


CONCLUSIONS
Real-time fusion of fhSPECT and US for preoperative anatomical co-registration of SLNs is feasible. However, before this approach can completely replace preoperative lymphatic imaging, further technical developments are needed.
Department of Nuclear Medicine, University Hospital of Würzburg, Oberdürrbacher Str. 6, 97080, Würzburg, Germany. bluemel_c@klinik.uni-wuerzburg.de.
Christina
C
Bluemel
Department of Nuclear Medicine, University Hospital of Würzburg, Oberdürrbacher Str. 6, 97080, Würzburg, Germany.
Gonca
G
Safak
Department of Obstetrics and Gynecology, Missionsärztliches Klinikum Würzburg, Würzburg, Germany.
Andreas
A
Cramer
Department of Obstetrics and Gynecology, University Hospital of Würzburg, Würzburg, Germany.
Achim
A
Wöckel
Department of Dermatology, Venerology and Allergology, University Hospital of Würzburg, Würzburg, Germany.
Anja
A
Gesierich
Institute of Pathology, University of Würzburg, Würzburg, Germany.
Elena
E
Hartmann
Department of Nuclear Medicine, University Hospital of Würzburg, Oberdürrbacher Str. 6, 97080, Würzburg, Germany.
Jan-Stefan
JS
Schmid
Department of Nuclear Medicine, University Hospital of Würzburg, Oberdürrbacher Str. 6, 97080, Würzburg, Germany.
Franz
F
Kaiser
Department of Nuclear Medicine, University Hospital of Würzburg, Oberdürrbacher Str. 6, 97080, Würzburg, Germany.
Andreas K
AK
Buck
Department of Nuclear Medicine, University Hospital of Würzburg, Oberdürrbacher Str. 6, 97080, Würzburg, Germany.|Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
Ken
K
Herrmann
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D061705:Image-Guided Biopsy / Q000379:methods*; D061305:Lymphoscintigraphy / Q000379:methods; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D010865:Pilot Projects; D011300:Preoperative Care; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000071036:Sentinel Lymph Node / Q000000981:diagnostic imaging* / Q000473:pathology*; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*; D013382:Subtraction Technique; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014463:Ultrasonography / Q000379:methods*
Freehand SPECT; Fusion; Hybrid imaging; SPECT/CT; Sentinel; Ultrasound