Use of Multiple-Tube Phantom

Abstract

Background: Native T1 relaxation time (T10) presents an important prerequisite to reliably quantify pharmacokinetic parameter like Ktrans (volume transfer constant). Native T1 value can be varied because of the inhomogeneity in the breast coil, thus influencing the Ktrans measurement. Purpose: The current study aims to design and use a phantom with multiple tubes for both breast cuffs to assess native T1 inhomogeneity across the dedicated molecular magnetic resonance (mMR) breast coil and adopt corrective method to spatially normalize T1 values to improve homogeneity. Materials and Methods: Two phantoms with multiple tubes (19 tubes) specially designed and filled with contrast medium with known T1 value were placed in each mMR breast coil cuff. Native T1 at various spatial locations was calculated applying dual flip angle sequence. Correction factors were derived at various spatial locations as a function of deviation of the native T1 value from phantom and applied to correct the native T1 relaxation time. Results: A statistically significant difference between native T1 values of the right and left anterior (P = 0.0095), middle (P = 0.0081), and posterior (P = 0.0004) parts of the breast coil. No significant difference was seen in the corrected T1 values between anterior (P = 0.402), middle (P = 0.305), and posterior (P = 0.349) aspects of both sides of the breast coil. Conclusion: Inhomogeneity in the native T1 value exists in dedicated mMR breast coil, and significant improvement can be achieved using specially designed external phantom with multiple tubes.

Ktrans Calculation Using Reference Method Corrected Native T10 for Breast Cancer Diagnosis

“…The acquisition of phantom image was done using DFA method to derive correction factor for T 1 value at each spatial location. [ 28 ] The correction factor so obtained was then applied to Native T 10 values of breast lesions of 39 patients that was spatially synchronized with the lesion. The patients were selected consecutively from the database between 2018 and 2021 with a mean age of 50 years (31–77 years) having a total 51 lesions who had undergone breast PET/MRI study as part of their diagnostic/staging workup with proven cancer on histopathology before or done subsequently after their PET/MRI scan.…”

“…Later on, Negi et al . [ 28 ] adopted an in vitro reference method to normalize T 1 distribution using an in-house designed multiple tube phantom placed within the breast coil cuffs and T 1 was calculated using DFA protocol. The T 1 values were normalized in the molecular magnetic resonance (mMR) breast coil-cuff by applying correction factors derived for each spatial location and observed that before the application of correction factors, T 1 distribution was inhomogeneous in different parts of each breast coil cuff as well as between the left and right coil cuff.…”