Korean J Radiol.  2013 Aug;14(4):662-672. 10.3348/kjr.2013.14.4.662.

True Progression versus Pseudoprogression in the Treatment of Glioblastomas: A Comparison Study of Normalized Cerebral Blood Volume and Apparent Diffusion Coefficient by Histogram Analysis

Affiliations
  • 1Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea. verocay@snuh.org
  • 2Department of Neurosurgery, Seoul National University College of Medicine, Seoul 110-744, Korea.
  • 3Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744, Korea.
  • 4Department of Pathology, Seoul National University College of Medicine, Seoul 110-744, Korea.
  • 5Department of Radiation Oncology, Seoul National University College of Medicine, Seoul 110-744, Korea.
  • 6Department of Radiology, School of Medicine of Kyung Hee University, Seoul 134-727, Korea.

Abstract


OBJECTIVE
The purpose of this study was to differentiate true progression from pseudoprogression of glioblastomas treated with concurrent chemoradiotherapy (CCRT) with temozolomide (TMZ) by using histogram analysis of apparent diffusion coefficient (ADC) and normalized cerebral blood volume (nCBV) maps.
MATERIALS AND METHODS
Twenty patients with histopathologically proven glioblastoma who had received CCRT with TMZ underwent perfusion-weighted imaging and diffusion-weighted imaging (b = 0, 1000 sec/mm2). The corresponding nCBV and ADC maps for the newly visible, entirely enhancing lesions were calculated after the completion of CCRT with TMZ. Two observers independently measured the histogram parameters of the nCBV and ADC maps. The histogram parameters between the true progression group (n = 10) and the pseudoprogression group (n = 10) were compared by use of an unpaired Student's t test and subsequent multivariable stepwise logistic regression analysis to determine the best predictors for the differential diagnosis between the two groups. Receiver operating characteristic analysis was employed to determine the best cutoff values for the histogram parameters that proved to be significant predictors for differentiating true progression from pseudoprogression. Intraclass correlation coefficient was used to determine the level of inter-observer reliability for the histogram parameters.
RESULTS
The 5th percentile value (C5) of the cumulative ADC histograms was a significant predictor for the differential diagnosis between true progression and pseudoprogression (p = 0.044 for observer 1; p = 0.011 for observer 2). Optimal cutoff values of 892 x 10-6 mm2/sec for observer 1 and 907 x 10-6 mm2/sec for observer 2 could help differentiate between the two groups with a sensitivity of 90% and 80%, respectively, a specificity of 90% and 80%, respectively, and an area under the curve of 0.880 and 0.840, respectively. There was no other significant differentiating parameter on the nCBV histograms. Inter-observer reliability was excellent or good for all histogram parameters (intraclass correlation coefficient range: 0.70-0.99).
CONCLUSION
The C5 of the cumulative ADC histogram can be a promising parameter for the differentiation of true progression from pseudoprogression of newly visible, entirely enhancing lesions after CCRT with TMZ for glioblastomas.

Keyword

Apparent diffusion coefficient; Cerebral blood volume; Glioblastoma multiforme; Histogram analysis; Pseudoprogression
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