MRI findings, including diffusion-weighted imaging and apparent diffusion coefficient value, in two cats with nasopharyngeal polyps and one cat with lymphoma

Toshiyuki Tanaka; Hideo Akiyoshi; Keiichiro Mie; Hidetaka Nishida

doi:10.1177/2055116918812254

MRI findings, including diffusion-weighted imaging and apparent diffusion coefficient value, in two cats with nasopharyngeal polyps and one cat with lymphoma

JFMS Open Rep. 2018 Nov 27;4(2):2055116918812254. doi: 10.1177/2055116918812254. eCollection 2018 Jul-Dec.

Authors

Toshiyuki Tanaka^{1

2}, Hideo Akiyoshi¹, Keiichiro Mie¹, Hidetaka Nishida¹

Affiliations

¹ Department of Advanced Clinical Medicine, School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan.
² Kinki Animal Medical Training institute, Osaka, Japan.

Abstract

Objectives: Most nasopharyngeal masses in cats are lymphomas or polyps. To our knowledge, there is no report of MRI findings, including diffusion-weighted imaging (DWI) or apparent diffusion coefficient (ADC) values, of nasopharyngeal lymphomas and nasopharyngeal polyps in cats. This study aimed to evaluate the MRI findings of nasopharyngeal lymphomas and nasopharyngeal polyps, including DWI and ADC values.

Methods: MRI examination was performed on two cats with a histologically confirmed nasopharyngeal polyp and one cat with lymphoma. The magnetic resonance scanning protocol included T2-weighted imaging (T2WI), T1-weighted imaging (T1WI) and DWI. An ADC map was created based on DWI. ADC values were then calculated.

Results: MRI of the nasopharyngeal polyps revealed well-defined masses with strong rim enhancement, mass-associated stalk-like structures and asymmetric tympanic bulla lesions. The polyps appeared hyperintense on T2WI, hypo- to isointense on T1WI, and of mixed intensity or hypointense on DWI. On the ADC map, the masses appeared hyperintense. The ADC values of the polyps were 2.07 × 10^-3 mm²/s and 2.28 × 10^-3 mm²/s. MRI examination of the nasopharyngeal lymphoma revealed a strongly enhancing heterogeneous lesion. The mass appeared mildly hyperintense on T2WI, isointense on T1WI and hyperintense on DWI. On the ADC map, the mass appeared hypointense. The ADC value of the mass was 0.46 ×10^-3 mm²/s. The ADC values of the nasopharyngeal polyps were higher than the ADC value of the nasopharyngeal lymphoma.

Conclusions and relevance: Measurement of ADC values may be useful for differentiating between nasopharyngeal polyps and nasopharyngeal lymphomas.

Keywords: ADC; DWI; MRI; T2 shine-through; lymphoma; nasopharyngeal polyp.