Perfusion Computed Tomography in Rectal Carcinoma: Influence of Optimization of the Patlak Range on Calculation of Equivalent Blood Volume and Flow Extraction.

PURPOSE: The aim of the study is to assess the influence of manual adjustment of the Patlak range in computed tomography (CT) perfusion analysis of rectal carcinoma compared with default range of the perfusion software. METHODS: This study was approved by the institutional review board and informed consent was obtained. Twenty-one patients (12 male, 9 female; mean age ± SD, 59 ± 11 years) with rectal cancer were included and underwent perfusion CT before preoperative chemoradiotherapy. Equivalent blood volume (BV) and flow-extraction (FE) were calculated using the Patlak plot model. Two perfusion sets were calculated per patient, a perfusion set using the default setting as provided by the software (dBV, dFE) and an optimized perfusion set after manual adaption of the Patlak range (aBV, aFE), which was limited to the intravascular space clearance of contrast to the extravascular space. Perfusion values calculated with both methods were compared for significance in differences using the Wilcoxon test. A P value of 0.05 or less was defined as statistically significant. RESULTS: Adjustment of the Patlak range statistically significantly influenced BV and FE calculation. Median dBV was 23.2 mL/100 mL (interquartile range [IQR], 12.1 mL/100 mL), whereas median aBV was 20.3 mL/100 mL (IQR, 10.9 mL/100 mL). The difference in BV was statistically significant ( P = 0.021). Median dFE was 8.3 mL/min/100 mL (IQR, 4.7 mL/min/100 mL), whereas median aFE was 15.4 mL/min/100 mL (IQR, 5.8 mL/min/100 mL). The difference in FE was statistically significant ( P < 0.001). CONCLUSIONS: Our findings indicate that in perfusion CT of rectal carcinoma, adjustment of the Patlak range may significantly influence BV and FE compared with default setting of the software. This may contribute to standardization in the use of this technique for functional imaging of rectal cancer.

Evaluation of the effect of routine packed red blood cell transfusion in anemic cervix cancer patients treated with radical radiotherapy.

PURPOSE: It is well established that anemia predicts diminished radiocurability in cervix cancer. However, the therapeutic benefit of measures to correct the anemia remains controversial. The objective of this study was to determine the impact of routine transfusion in patients with hemoglobin level (hb-l) < or =11 g/dl. METHODS AND MATERIALS: Since 1985, it has been departmental policy to attempt to correct hb-l < or =11 g/dl before and/or during radiotherapy by red blood cell transfusion (RBCT) in patients undergoing radical radiotherapy for primary cervix cancer. To assess the benefit of RBCT, the charts of 204 patients (FIGO: IB-IV) treated until 1997 were reviewed. Parameters analyzed for their impact on disease-specific survival (DSS), pelvic control (PC), and metastases-free survival (MFS) included pretreatment hb-l, treatment hb-l, stage, tumor size, and lymph node status. To determine any differences in outcome according to type of anemia, a separate analysis was performed, grouping patients by cause of anemia (tumor vs. other medical illness related). RESULTS: Each of the parameters tested was significantly correlated with the end points studied in univariate analysis. Patients whose hb-l were corrected (18.5%) had an outcome that did not differ significantly from that of nontransfused patients, whereas DSS, PC, and MFS (all: p < 0.001) were significantly decreased in nonresponders to RBCT. Subgroup analysis showed no impact of hb-l in patients with other medical illness-related anemia (n = 12). In multivariate analysis treatment, but not pretreatment, hb-l remained predictive for DSS, PC, and MFS. Persistent anemia was associated with a significantly increased risk of death (relative risk: 2.1) and pelvic failure (relative risk: 2.4) compared with nontransfused patients. If only patients with tumor anemia were considered, the respective risks increased (2.7; 3.6). None of the patients with other causes of anemia recurred, whether or not their hb-l was maintained. Assessment of the therapeutic gain in patients who responded to RBCT showed improved PC (p = 0.02) and a trend toward increased DSS (p = 0.06), but no effect on MFS after adjustment for tumor size and lymph node status. CONCLUSION: Treatment hb-l, in addition to tumor size and lymph node status, independently predicted outcome. Although our final multivariate analysis showed a therapeutic benefit for patients whose hb-l was corrected, the response to RBCT was disappointing. Results of our subgroup analysis suggest that the cause of anemia in patients with cervical cancer warrants in-depth investigation.