Hemosiderin deposition in papillary renal cell carcinoma and its potential to mask enhancement on MRI: analysis of 110 c
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Hemosiderin deposition in papillary renal cell carcinoma and its potential to mask enhancement on MRI: analysis of 110 cases Hiroaki Takahashi 1 & Akira Kawashima 2 & Akitoshi Inoue 1 & Kazuto Kozaka 1 & Theodora A. Potretzke 1 & Adam T. Froemming 1 & Stephen A. Boorjian 3 & Mitchell R. Humphreys 4 & Naoki Takahashi 1 Received: 19 December 2019 / Revised: 16 April 2020 / Accepted: 28 May 2020 # European Society of Radiology 2020
Abstract Objectives To evaluate the relationship between imperceptible T1 enhancement of papillary renal cell carcinoma (pRCC) on MR and intratumoral hemosiderin deposition. Methods One hundred ten pRCCs (≤ 7 cm) were evaluated by MR with in- and opposed-phase spoiled gradient echo (GRE) and T1-weighted spoiled GRE with fat suppression before and after contrast. Hemosiderin deposition was assessed by SIindex and Dindex on in- and opposed-phase images. SIindex and Dindex are calculated as (SIin − SIopp)/(SIin) × 100, where SIin and SIopp are tumor signal intensities on in- and opposed-phase images and (Din)/(Dopp), where Din and Dopp are tumor diameters on in- and opposed-phase images, respectively. The degree of tumor enhancement was classified as grade 1 (no), grade 2 (subtle), or grade 3 (definite). Tumor enhancement on CT was assessed when available. Results Five (5%), 10 (9%), and 95 (86%) tumors were categorized as grades 1, 2, and 3 enhancement, respectively. The mean SIindex was − 33.9, − 25.3, and 1.00, whereas the mean Dindex was 1.26, 1.05, and 1.00 in tumors with grades 1, 2, and 3 enhancement, respectively. Tumors with grade 1 enhancement had significantly lower SIindex (p = 0.001) and higher Dindex (p = 0.005) than those with grade 3 enhancement. Among six tumors with grade 1 or 2 enhancement and available CT, four tumors showed > 20 HU enhancement. Conclusions pRCC with no subjective enhancement on contrast-enhanced MR showed hemosiderin deposition evident by lower SIindex and higher Dindex. Hemosiderin deposition might mask the tumor enhancement on MR. Key Points • 5% of papillary renal cell carcinoma showed imperceptible enhancement on contrast-enhanced MR. • Hemosiderin deposition in papillary renal cell carcinoma might mask the tumor enhancement on contrast-enhanced MR due to T2/T2*-shortening effects. • A renal lesion with extensive hemosiderin deposition but no perceptible enhancement on MR should be considered suspicious for papillary renal cell carcinoma. Keywords Papillary renal cell carcinoma . Hemosiderin . Magnetic resonance imaging . Chemical shift imagings . Contrast agent
* Naoki Takahashi [email protected] 1
Department of Diagnostic Radiology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA
2
Department of Diagnostic Radiology, Mayo Clinic, Phoenix, AZ, USA
3
Department of Urology, Mayo Clinic, Rochester, MN, USA
4
Department of Urology, Mayo Clinic, Phoenix, AZ, USA
Abbreviations ER Enhancement ratio FSE Fast spin echo GRE Gradient echo ICC Interclass correlation coefficient pRCC Papillary renal cell carcinoma RCC Renal cel
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