title: MR imaging of intracranial hemangiopericytomas.
abstract: OBJECTIVE
  To describe the MR features of primary intracranial hemangiopericytomas (HPCs) on conventional imaging, diffusion and MR spectroscopy and aim to determinate distinguishing features from meningiomas.
  
  
  METHODS
  From 2006 to 2012, seven patients with pathologically confirmed primary intracranial HPCs were included. The clinical data, conventional MR findings (n=7), DWI features (n=7) and MR spectroscopy (n=5) were retrospectively analyzed. ADC values of the HPCs (n=7) were measured on ADC map and were compared with that of contralateral normal white matter.
  
  
  RESULTS
  Of the seven HPCs, four were anaplastic HPCs (WHO grade III) and three were HPCs (WHO grade II). MR pattern consisted in lobulated or irregular margin tumors in all cases with cross-leaf growth on both side of the falx in two cases. The lesions showed mainly iso signal (n=4) on T1 WI and heterogeneous high signal (n=5) on T2 WI. Heterogenity was mainly related to intra tumoral hemorrhage (n=4), and proeminent intratumoral flow voids (n=3). Marked heterogeneous enhancement (n=5) with dural tail (n=4) was noted. All tumours showed significant peritumoral edema. ADC values of the tumor tissue component range between 0.638 and 1.50×10(-3)mm/s(2) (average = 1,02). Three grade II HPCs showed higher values compared to normal parenchyma ADC (range between 0.772 and 0.930×10(-3)mm/s(2) with average of 0.830), whereas grade III HPCs showed either equal (three cases) or decreased ADC values (one case). MRS showed in all cases markedly increased Cho with lip/lac peak, decreased Cr and almost absent NAA. High mI peak with large glutamine/glutamate were noted in the three grade II HPCs.
  
  
  CONCLUSIONS
  Conventional MR pattern when combined with DWI and MRS findings are highly suggestive of HPC and appear valuable data to differentiate HPCs from meningiomas.
authors.affiliation: Service de radiologie, hôpital Sahloul, route ceinture, 4011 Sousse, Tunisia. Electronic address: dr.nmama@gmail.com.
authors.forename: N
authors.initials: N
authors.lastname: Mama
authors.affiliation: Service de radiologie, hôpital Sahloul, route ceinture, 4011 Sousse, Tunisia.
authors.forename: A
authors.initials: A
authors.lastname: Ben Abdallah
authors.affiliation: Service de radiologie, hôpital Sahloul, route ceinture, 4011 Sousse, Tunisia.
authors.forename: I
authors.initials: I
authors.lastname: Hasni
authors.affiliation: Service de radiologie, hôpital Sahloul, route ceinture, 4011 Sousse, Tunisia.
authors.forename: K
authors.initials: K
authors.lastname: Kadri
authors.affiliation: Service de radiologie, hôpital Sahloul, route ceinture, 4011 Sousse, Tunisia.
authors.forename: N
authors.initials: N
authors.lastname: Arifa
authors.affiliation: Service de neurochirurgie, hôpital Sahloul, route ceinture, 4011 Sousse, Tunisia.
authors.forename: M
authors.initials: M
authors.lastname: Ladib
authors.affiliation: Service de radiologie, hôpital Sahloul, route ceinture, 4011 Sousse, Tunisia.
authors.forename: K
authors.initials: K
authors.lastname: Tlili-Graiess
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D015415:Biomarkers / Q000032:analysis; D001932:Brain Neoplasms / Q000737:chemistry / Q000175:diagnosis*; D002794:Choline / Q000032:analysis*; D003401:Creatine / Q000032:analysis*; D005260:Female; D006393:Hemangiopericytoma / Q000737:chemistry / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D057054:Molecular Imaging / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D015415:Biomarkers; D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline
keywords: Anaplastic hemangiopericytoma; Hemangiopericytoma; MR spectroscopy; MRI; diffusion