title: Perfusion Computed Tomography (PCT) adopting different perfusion metrics: recurrence of brain metastasis or radiation necrosis?
abstract: OBJECTIVE
  Different perfusion metrics were investigated to determine the accuracy of Perfusion CT (PCT) in differentiating recurrence of brain metastases from radiation necrosis in patients who previously underwent stereotactic radiation therapy (SRT).
  
  
  METHODS
  Twenty patients previously treated with SRT underwent PCT examination of the brain. Normalized Cerebral Blood Volume (nCBV) values within the region of interest (ROI) were calculated. Fractional volumes at nCBV values between 1.0 and 2.25, defined as V(1.0)-V(2.25), were derived as alternative metrics and compared to the conventional method based on the mean CBV value within the lesion (nCBV(mean)). The Mann-Whitney test was used to compare the two patient's groups with recurrence and radiation necrosis with respect to the different nCBV metrics. Predictive powers and optimal thresholds for both the nCBV(mean) and the V(1.0)-V(2.25) were evaluated using the Receiver Operating Characteristic Curves. The gold standard was represented either by the histopathological examination or the Magnetic Resonance (MR) imaging follow-up longer than six months.
  
  
  CONCLUSIONS
  The differences between the patient's group with recurrence and that with radiation necrosis resulted statistically significant for all the metrics, showing the lowest p-value for V(1.75) and V(2). The metrics based on the fractional volumes were found to show higher predictive powers, with the highest value of 0.96 for V(2.0). Quantitative analysis of the CBV map deriving different metrics may potentially improve the diagnostic accuracy of PCT in differentiating brain metastasis recurrence from radiation necrosis.
authors: Radiology and Diagnostic Imaging Department, Istituto Regina Elena, Via Elio Chianesi 53, 00144 Rome, Italy. vidiri@ifo.it
authors: Antonello
authors: A
authors: Vidiri
authors: Antonino
authors: A
authors: Guerrisi
authors: Valentina
authors: V
authors: Pinzi
authors: Alessandra
authors: A
authors: Fabi
authors: Maria Alessandra
authors: MA
authors: Mirri
authors: Alfredo
authors: A
authors: Pompili
authors: Nicoletta
authors: N
authors: Caporale
authors: Andrea
authors: A
authors: Pace
authors: Marcello
authors: M
authors: Crecco
authors: Simona
authors: S
authors: Marzi
mesh_terms: D000328:Adult; D000368:Aged; D001810:Blood Volume; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000556:secondary; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007479:Iopamidol; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D011832:Radiation Injuries / Q000000981:diagnostic imaging*; D011857:Radiographic Image Interpretation, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007479:Iopamidol