Pilot study to evaluate the efficacy of lymphotropic nanoparticle enhanced MRI for diagnosis of metastatic disease in canine head and neck tumours

Abstract

This pilot study is designed to determine if lymphotropic nanoparticle enhanced MRI (LNMRI) is a viable technique for staging of naturally occurring canine malignant head and neck tumours. Previous imaging studies in veterinary medicine have shown variable sensitivity and specificity for determining metastasis for local lymph nodes in head and neck tumours. LNMRI utilizes ultra-small superparamagnetic iron oxide nanoparticles (USPIOs) to help in the detection of metastatic disease in lymph nodes.USPIOs are phagocytized and localized to normal lymph nodes where they assist in evaluation for regions of effacement by cancerous cells. Six dogs underwent LNMRI for the diagnosis of metastatic lymph nodes. A truncated MRI consisting of transverse images of T2, T1 pre-and post-contrast and T2* sequences were evaluated for presence of metastasis. Sentinel lymph nodes and lymph nodes with possible metastatic lesions were surgically excised for histological evaluation. In the initial phase of this study, 24 lymph nodes were included in analysis. Subjective observation by the primary investigator had a calculated sensitivity and specificity of 100% and 88% based on histological results. There were no negative side effects to the USPIOs noted in the limited number of patients in this study. Percentage signal intensity loss was calculated and found to be significantly different between metastatic and nonmetastatic lymph nodes (P-value = .038). In conclusion, this pilot study shows that LNMRI has the potential to be a sensitive and specific method of diagnosing lymph node metastasis. Further research is warranted to determine if this method is clinically applicable and accurate.

Lymphotropic nanoparticle magnetic resonance imaging for diagnosing metastatic lymph nodes in dogs with malignant head and neck tumours

“…T2 and T1 pre-and post-contrast images, as well as the CT For the initial cohort of 12 dogs (Year 1) where pre-USPIO images were available, measurement of percentage signal intensity loss (PSIL) was performed retrospectively at selected regions of interest (ROIs), as previously described. 27 Given the lack of pre-USPIO images for the dogs in Year 2, quantitative analysis for PSIL was not possible. Evaluation of presence of metastasis on imaging was entirely subjective based on one radiologist's opinion (LG).…”

“…In addition, LNMRI made it possible to identify metastatic nodules within an otherwise unaffected lymph node and to separate out effaced mandibular lymph nodes from reactive mandibular lymph nodes that were in the same lymphocentrum. This study was limited by a small number of patients and the fact that only the sentinel lymph nodes and lymph nodes that were deemed suspicious for metastasis were extirpated 27 . The results of this initial pilot study were used as a foundation for this more extensive study would allow for a better assessment of the true sensitivity and specificity of this non‐invasive staging method.…”

“…This study was limited by a small number of patients and the fact that only the sentinel lymph nodes and lymph nodes that were deemed suspicious for metastasis were extirpated. 27 The results of this initial pilot study were used as a foundation for this more extensive study would allow for a better assessment of the true sensitivity and specificity of this non-invasive staging method.…”

Ferumoxytol‐enhanced magnetic resonance angiography provides comparable vascular conspicuity to CT angiography in dogs with intrahepatic portosystemic shunts

“…As to the safety of ferumoxytol in dogs, the original toxicity studies for FDA approval of ferumoxytol (Feraheme, AMAG pharmaceuticals, Waltham, MA) were performed in canines with no negative effects noted. Two recent canine studies did not find any side effects of ferumoxytol administration 22,28 …”

“…For this reason, ferumoxytol has recently garnered interest for vascular MRI in human patients with renal impairment. The long blood residence time and reticuloendothelial metabolism allow for three different imaging phases with ferumoxytol: first pass arterial imaging, steady state blood pool imaging, and tissue phase imaging 21,22 . In this study, we used the steady state blood pool phase to image the abdominal vasculature.…”