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Diffusion-weighted quantitative MRI of pleural abnormalities: Intra- and interobserver variability in the apparent
Adriano Massimiliano Priola1, Sandro Massimo Priola1, Dario Gned1
1Department of Diagnostic Imaging, San Luigi Gonzaga University Hospital, Orbassano (Torino), Italy.
Purpose:
To assess intra- and interobserver variability in the apparent diffusion coefficient (ADC) measurements of pleural abnormalities.
Materials And Methods:
Diffusion-weighted magnetic resonance imaging was performed in 34 patients to characterize pleural abnormalities, with a 1.5T unit at b values of 0/150/500/800 sec/mm2 . In two sessions held 3 months apart, on perfusion-free ADC maps, two independent readers measured the ADC of pleural abnormalities (two readings for each reader in each case) using different methods of region-of-interest (ROI) positioning. In three methods, freehand ROIs were drawn within tumor boundaries to encompass the entire lesion on one or more axial slices (whole tumor volume [WTV], three slices observer-defined [TSOD], single-slice [SS]), while in two methods one or more ROIs were placed on the more restricted areas (multiple small round ROI [MSR], one small round ROI [OSR]). Measurement variability between readings by each reader (intraobserver repeatability) and between readers in first reading (interobserver repeatability) were assessed using intraclass correlation coefficient (ICC) and coefficient of variation (CoV). Analysis of variance (ANOVA) was performed to compare ADC values between the different methods. The measurement time of each case for all methods in first reading was recorded and compared between methods and readers.
Results:
All methods demonstrated good (MSR, OSR) and excellent (WTV, TSOD, SS) intra- and interreader agreement, with best and worst repeatability in WTV (lower ICC, 0.977; higher CoV, 3.5%) and OSR (lower ICC, 0.625; higher CoV, 22.8%), respectively. The lower 95% confidence interval of ICC resulted in fair to moderate agreement for OSR (up to 0.379) and in excellent agreement for WTV, TSV, and SS (up to 0.918). ADC values of OSR and MSR were significantly lower compared to other methods (P < 0.001). The OSR and SS required less measurement time (10 and 21/22 sec, respectively) compared to the others (P < 0.0001), while the WTV required the longest measurement time (132/134 sec) (P < 0.0001).
Conclusion:
ADC measurements of pleural abnormalities are repeatable. The SS method has excellent repeatability, similar to WTV, but requires significantly less measurement time. Thus, its use should be preferred in clinical practice.
Level Of Evidence:
4 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:769-782.
Insights
Apparent diffusion coefficient (ADC) measurements for pleural abnormalities show good repeatability. The single-slice (SS) method offers excellent consistency and is faster than whole tumor volume (WTV) analysis, making it ideal for clinical use.
Area of Science:
- Radiology and Medical Imaging
- Oncology
- Pulmonology
Background:
- Diffusion-weighted MRI is crucial for characterizing pleural abnormalities.
- Accurate apparent diffusion coefficient (ADC) measurements are vital for assessing these lesions.
- Understanding measurement variability is key to reliable clinical interpretation.
Purpose of the Study:
- To evaluate the intra- and interobserver variability of ADC measurements in pleural abnormalities.
- To compare different region-of-interest (ROI) positioning methods for ADC quantification.
- To determine the most efficient and reliable method for clinical application.
Main Methods:
- Diffusion-weighted MRI performed on 34 patients at 1.5T with multiple b values.
- Two independent readers assessed ADC values using five distinct ROI methods (WTV, TSOD, SS, MSR, OSR).
- Intra- and interreader agreement assessed using ICC and CoV; measurement times recorded.
Main Results:
- All methods showed good to excellent intra- and interreader agreement.
- The single-slice (SS) method demonstrated excellent repeatability, comparable to whole tumor volume (WTV).
- SS and OSR methods required significantly less measurement time than WTV and TSOD.
Conclusions:
- ADC measurements of pleural abnormalities are repeatable across various methods.
- The SS method provides excellent repeatability with substantially reduced measurement time.
- The SS method is recommended for routine clinical practice due to its efficiency and reliability.
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