MR imaging of renal cortical tumours: qualitative and quantitative chemical shift imaging parameters.

Abstract

OBJECTIVES:

To assess qualitative and quantitative chemical shift MRI parameters of renal cortical tumours.

METHODS:

A total of 251 consecutive patients underwent 1.5-T MRI before nephrectomy. Two readers (R1, R2) independently evaluated all tumours visually for a decrease in signal intensity (SI) on opposed- compared with in-phase chemical shift images. In addition, SI was measured on in- and opposed-phase images (SI(IP), SI(OP)) and the chemical shift index was calculated as a measure of percentage SI change. Histopathology served as the standard of reference.

RESULTS:

A visual decrease in SI was identified significantly more often in clear cell renal cell carcinoma (RCCs) (R1, 73 %; R2, 64 %) and angiomyolipomas (both, 80 %) than in oncocytomas (29 %, 12 %), papillary (29 %, 17 %) and chromophobe RCCs (13 %, 9 %; all, P < 0.05). Median chemical shift index was significantly greater in clear cell RCC and angiomyolipoma than in the other histological subtypes (both, P < 0.001). Interobserver agreement was fair for visual (kappa, 0.4) and excellent for quantitative analysis (concordance correlation coefficient, 0.80).

CONCLUSIONS:

A decrease in SI on opposed-phase chemical shift images is not an identifying feature of clear cell RCCs or angiomyolipomas, but can also be observed in oncocytomas, papillary and chromophobe RCCs. After excluding angiomyolipomas, a decrease in SI of more than 25 % was diagnostic for clear cell RCCs.

KEY POINTS:

• Chemical shift MRI offers new information about fat within renal tumours. • Opposed-phase signal decrease can be observed in all renal cortical tumours. • A greater than 25 % decrease in signal appears to be diagnostic for clear cell RCCs.

• Authors: Christoph A Karlo, Olivio F Donati, Irene A Burger, Junting Zheng, Chaya S Moskowitz, Hedvig Hricak, Oguz Akin
• Journal: European radiology (Eur Radiol) Vol. 23 Issue 6 Pg. 1738-44 (Jun 2013) ISSN: 1432-1084 [Electronic] Germany
• PMID: 23300041 (Publication Type: Journal Article)

Topics

• Adenoma, Oxyphilic (diagnosis, pathology)
• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Angiomyolipoma (diagnosis, pathology)
• Body Mass Index
• Carcinoma, Papillary (diagnosis, pathology)
• Carcinoma, Renal Cell (diagnosis, pathology)
• Female
• Humans
• Kidney (pathology)
• Kidney Neoplasms (diagnosis, pathology)
• Magnetic Resonance Imaging (methods)
• Male
• Middle Aged
• Nephrectomy (methods)
• Observer Variation
• Young Adult