Assessment of time-resolved renal diffusion parameters over the entire cardiac cycle.

OBJECT: To assess changes diffusion properties of renal cortex over the entire cardiac cycle using electrocardiogram-gated respiratory-triggered dynamic diffusion-weighted imaging (DWI). MATERIALS AND METHODS: 20 healthy volunteers were investigated on a 1.5 T MR scanner. Blood flow velocity within the renal arteries was determined by electrocardiogram-gated phase-contrast measurements. For dynamic renal DWI, an electrocardiogram-gated respiratory-triggered coronal single-slice EPI sequence was acquired at 14 times at 20, 70, 120, 170, …, 570, 620, 720 ms after the R-wave over the cardiac cycle. ROI measurements were performed by two authors in the renal cortex on apparent diffusion coefficient (ADC) maps. A pulsatility index was calculated for ADC as maximal percentage change. Five subjects were measured twice to assess scan-rescan reproducibility. RESULTS: Flow measurements exhibited a minimum velocity of 15.7 ±â€¯4.3 cm/s during the R-wave and a maximum of 43.2 ±â€¯10.4 cm/s at 182.5 ±â€¯48.3 ms after the R-wave. A minimal mean ADC of 2.19 ±â€¯0.09 × 10-3 mm2/s was observed during the R-wave. A maximum mean ADC of 2.85 ±â€¯0.20 × 10-3 mm2/s was measured 193 ±â€¯57 ms after the R-wave. The mean ADC pulsatility index in the renal cortex was 29.9 ±â€¯5.8%. ADC variation exhibited a significant correlation with pulsatile blood flow velocity. The scan-rescan reproducibility in this study had a low deviation of 0.3 ±â€¯0.1%. The inter-reader reproducibility was 2.9 ±â€¯0.6%. CONCLUSION: Renal ADCs exhibit pulsatile characteristics. Due to the significant difference of systolic and diastolic ADCs, the pulsatility index can be calculated.

Cost-effectiveness of hybrid PET/CT for staging of non-small cell lung cancer.

UNLABELLED: Although the diagnostic effectiveness of integrated PET/CT for staging of non-small cell lung cancer (NSCLC) has already been proven, it remains to be determined if tumor staging with combined metabolic and anatomic imaging is also cost-effective. The objective of this study was to evaluate from a payers' perspective the cost-effectiveness of staging NSCLC with CT alone (representing the mainstay diagnostic test) and with integrated PET/CT. METHODS: The study is based on 172 NSCLC patients from a prospective clinical study who underwent diagnostic, contrast-enhanced helical CT and integrated PET/CT. Imaging was performed at the University Hospital Ulm between May 2002 and December 2004. To calculate treatment costs, we differentiated among cost for diagnosis, cost for nonsurgical treatment according to the clinical diagnosis, and cost for surgical procedures according to the clinical tumor stage. RESULTS: The diagnostic effectiveness in terms of correct TNM staging was 40% (31/77) for CT alone and 60% (46/77) for PET/CT. For the assessment of resectability (tumor stages Ia-IIIa vs. IIIb-IV), 65 of 77 patients (84%) were staged correctly by PET/CT (CT alone, 70% [54/77]). The incremental cost-effectiveness ratios per correctly staged patient were $3,508 for PET/CT versus CT alone. The incremental cost-effectiveness ratios per quality-adjusted life year gained were $79,878 for PET/CT vs. CT alone, decreasing to $69,563 assuming a reduced loss of utility (0.10 quality-adjusted life years) due to surgical morbidity. CONCLUSION: Cost-effectiveness analyses showed that costs for PET/CT are within the commonly accepted range for diagnostic tests or therapies. Therefore, reimbursement of PET/CT for NSCLC staging can be also recommended from an economic point of view.