Non Visualised Sentinel Lymph Nodes on Lymphoscintigraphy – Why Size Matters

Introduction: Failure of sentinel lymph node visualisation on lymphoscintigraphy for melanoma has been reported to occur at rates of 1-3% ^1,2. A variety of reasons for failure of uptake have been implicated ³, including but not limited to technical error.

 

Aim: To measure compliance with existing nuclear medicine guidelines and to identify the rate of and factors relating to non visualisation of sentinel lymph nodes on lymphoscintigraphy.

 

Methods: A retrospective review of the 12 months preceding the audit start date was carried out to determine the initial rate of non-visualisation of sentinel lymph nodes on lymphoscintigraphy. A prospective single institution closed loop audit was carried out over a 6 month period. Identification of factors that may be contributing to non-visiualisation of sentinal lymph nodes was undertaken. Interventions for improvement in practice were instituted after the first 3 months of audit. The impact of implemented interventions was then audited over the following 3 month period.

 

Results: 12/59 patients (20%) undergoing sentinel lymph node biopsy had failure of visualisation on lymphoscintigraphy during the retrospective study period. 1/11 (9%) of patients had failure of sentinel lymph node visualization during the initial audit period, improved to 0/11 following several improvement interventions. Factors relating to failure of uptake were identified, including radiocolloid particle size.

 

Conclusion: This closed loop audit significantly improved the success rate of sentinel lymph node success at our institution in line with current standards. The physical and pharmaceutical properties of radiocolloids impact on successful visualisation of SLN on lymphoscintography. Radiocolloid particle size is relevant for appropriate timing of lymphoscintigraphy following injection. These results have implications for a proposed national multi-centre audit of sentinel lymph node biopsy for melanoma in Ireland.

 

 

 

References:

1. Nonvisualized sentinel lymph nodes on lymphoscintigraphy in melanoma: predictive factors and surgical outcomes. Schuitevoerder, Grinlington, Stevens et al.

Nuclear Medicine Communications: 2017; 38(5): 383-387

2. Sentinel node biopsy status is strongly predictive of survival in cutaneous melanoma: Extended follow-up of Oxford patients from 1998 to 2014.

Thomson D, Rughani MG, Kuo R, Cassell OSC.

Journal of Plastic, Reconstructive & Aesthetic Surgery 2017; 70:1397e1403

3. False Negative Sentinel Lymph Node Biopsies in Melanoma May Result From Deficiencies in Nuclear Medicine, Surgery, or Pathology.  Kalim, Scolyer, Li et al.

Ann Surg 2008;247: 1003–1010