Real-time ultrasound and freehand-SPECT. Experiences with sentinel lymph node mapping

Area of Science:

• Medical Imaging
• Oncology
• Nuclear Medicine

Background:

• Sentinel lymph node (SLN) imaging is crucial for cancer staging.
• Current SLN imaging methods have limitations in precise localization.
• Hybrid imaging offers potential for improved diagnostic accuracy.

Purpose of the Study:

• To evaluate the feasibility and applicability of a hybrid freehand SPECT/ultrasound (fh-SPECT/US) imaging concept.
• To assess the accuracy of fh-SPECT/US for SLN imaging in breast cancer and melanoma patients.
• To identify technical limitations of the fh-SPECT/US system.

Main Methods:

• 18 patients with breast cancer or melanoma underwent standard SLN scintigraphy.
• Handheld gamma camera-based fh-SPECT was performed using declipse®SPECT.
• Sensor-navigated ultrasound was used to create superimposed fh-SPECT/US images.

Main Results:

• Co-registration accuracy varied, with deviations ranging from <1 cm to >1 cm in most patients.
• No lymph node was detected in the region of highest activity in 2/18 cases.
• fh-SPECT reconstruction artifacts occurred in 6/18 examinations, impacting image quality.

Conclusions:

• The hybrid fh-SPECT/US imaging concept is feasible and technically successful for SLN imaging.
• Significant technical limitations exist in fh-SPECT quality and fusion precision.
• Optimization of SPECT quality and co-registration is needed for clinical application in preoperative lymph node therapy planning.