title: Intracellular lipid in clear cell renal cell carcinoma tumor thrombus and metastases detected by chemical shift (in and opposed phase) MRI: radiologic-pathologic correlation.
abstract: BACKGROUND
  Clear cell renal cell carcinoma (RRC) characteristically contain intracellular lipid which is also detectable in tumor thrombus and metastases.
  
  
  OBJECTIVE
  To assess the incidence of intracellular lipid in clear cell RCC metastases and tumor thrombus using chemical shift MRI.
  
  
  METHODS
  With REB approval, 33 consecutive patients with clear cell RCC and tumor thrombus/metastatic disease underwent magnetic resonance imaging (MRI) over a 10-year period. Diagnosis was established by histopathology for tumor thrombi (n = 25) and metastases (n = 15) or growth for metastases (n = 14). Two blinded radiologists independently assessed for a signal intensity (SI) drop at chemical shift MRI (indicative of intracellular lipid) and a third radiologist established consensus. Chemical shift SI (CS-SI) index ([SItumorIP - SItumorOP]/SITumorIP x 100) was calculated. Inter-observer agreement was assessed using intra-class correlation (ICC) and tests of association were performed using the Chi-square test and Spearman correlation.
  
  
  RESULTS
  Using CS-MRI, intracellular lipid was detected in 36.4% of clear cell RCC, with moderate agreement, (ICC = 0.5). Intracellular lipid was detected in 20% of tumor thrombi and 20% of metastases with strong agreement (ICC = 0.73). Intracellular lipid within tumor thrombi/metastases was not associated with lipid within the primary tumor (P = 0.09). There was a correlation in CS-SI index between primary tumor and thrombi/metastases when lipid was detected in both lesions (r = 0.91, P = 0.005); however, there was no correlation when lipid was not detected in both lesions (r = -0.09, P = 0.72).
  
  
  CONCLUSIONS
  The presence of intracellular lipid in tumor thrombus and metastases from clear cell RCC is uncommon and, is not necessarily associated with lipid within the primary tumor at chemical shift MRI.
authors: Department of Radiology, The Ottawa Hopital, Ottawa, Canada.
authors: Bardia
authors: B
authors: Moosavi
authors: Department of Radiology, The Ottawa Hopital, Ottawa, Canada.
authors: Wael M
authors: WM
authors: Shabana
authors: Department of Radiology, The Ottawa Hopital, Ottawa, Canada.
authors: Mohamed
authors: M
authors: El-Khodary
authors: Department of Radiology, The Ottawa Hopital, Ottawa, Canada.
authors: Christian B
authors: CB
authors: van der Pol
authors: Department of Anatomic Pathology, The Ottawa Hospital, Ottawa, Canada.
authors: Trevor A
authors: TA
authors: Flood
authors: Department of Radiology, The Ottawa Hopital, Ottawa, Canada.
authors: Mathew Df
authors: MD
authors: McInnes
authors: Department of Radiology, The Ottawa Hopital, Ottawa, Canada nschieda@toh.on.ca.
authors: Nicola
authors: N
authors: Schieda
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000150:complications / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000150:complications / Q000473:pathology*; D008055:Lipids; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000473:pathology*; D015588:Observer Variation; D015203:Reproducibility of Results; D013927:Thrombosis / Q000150:complications / Q000473:pathology*; D055815:Young Adult
chemical_list: D008055:Lipids
keywords: Urinary; adults; kidney; magnetic resonance imaging (MRI); metastases