Measuring the apparent diffusion coefficient in primary rectal tumors: is there a benefit in performing histogram...

Area of Science:

• Radiology and Medical Imaging
• Oncology
• Quantitative MRI

Background:

• Apparent diffusion coefficient (ADC) is a key prognostic imaging marker in rectal cancer.
• Current methods rely on precise, time-consuming manual tumor delineations for mean ADC values.

Purpose of the Study:

• To evaluate non-precise circular delineation with histogram analysis as a simpler alternative for ADC measurements.
• To determine if histogram analyses offer additional prognostic value beyond mean ADC in rectal cancer.

Main Methods:

• 37 patients with rectal cancer underwent MRI with diffusion-weighted imaging (DWI).
• Volumes-of-interest (VOIs) were created using precise manual delineation and non-precise circular delineation.
• Mean ADC and various histogram metrics were calculated and compared.
• Delineation time and correlation with prognostic parameters were assessed.

Main Results:

• Non-precise delineation significantly reduced measurement time compared to precise methods.
• The 45th percentile of non-precise delineation showed good correlation with precise mean ADC values (ICC 0.71-0.75).
• No significant prognostic value was found for mean ADC or histogram parameters; only tumor volume correlated with clinical staging.

Conclusions:

• Non-precise tumor delineation with histogram analysis (45th ADC percentile) is a viable, less cumbersome alternative for obtaining ADC values similar to precise methods.
• Histogram analyses do not provide additional prognostic information in this cohort.