The Influence of Temperature and Age on the T1 Relaxation Time of the Equine Distal Limb

Abstract

The extent of fat suppression using short tau inversion recovery (STIR) imaging is variable between horses. Our aim was to determine if patient's age and/or hoof temperature have an influence on the T(1) relaxation time of bone marrow in the equine distal limb, thereby affecting the suppression of fat signal. Magnetic resonance imaging was conducted on standing horses and cadaver samples using a low-field magnet (0.27 T). The hoof temperature was measured at the lateral side of the coronary band. A modified inversion recovery fast spin-echo (IR-FSE) sequence was used to measure the signal intensity for a range of inversion times (TIs) at six different regions of interest (ROI): (1) distal aspect of the proximal phalanx, (2) proximal aspect of the middle phalanx, (3) distal aspect of the middle phalanx, (4) navicular bone, (5) proximal aspect of the distal phalanx, and (6) distal aspect of the distal phalanx. The T(1) of the bone marrow in the equine distal limb was calculated from the results and was found to increase by 3.13 ± 0.08 (SE) ms/°C. There was no significant effect of age (2-16 years) but the T(1) values measured from the limbs of young (< 1 year) animals were considerably longer (32.6 ± 1.7 (SE) ms). Similar effects of temperature and age were found for all measured ROIs but there were significant differences in the mean values of T(1) , ranging from +7.7 (distal aspect of the distal phalanx) to -13.2 ms (distal aspect of the proximal phalanx).

Comparison of inversion recovery gradient echo with inversion recovery fast spin echo techniques for magnetic resonance imaging detection of navicular bone marrow lesions in horses

“…Besides motion artifacts, other factors may contribute to suboptimal image quality in inversion recovery sequences, namely choice of an improper inversion time relative to the temperature of the limb or to the age of the horse may lead to deficient fat signal suppression. 16 In the study reported here, such horses with increased SI on STIR images but no manifestation of phase-cancellation artifact on T2*-weighted images were allocated to the no-BML group. However, it remains possible that data from horses with abnormal SI on T1-weighted and T2*-weighted images and increased SI in the fatsuppressed images due to a combination of a BML and lack of fat saturation might have altered the results by artificially increasing the measured SNR and CNR.…”

“…The manufacturer also proposes 2 additional versions of the STIR sequence with shorter and longer TI (named STIR + and STIR -, respectively) to increase fat suppression depending on limb temperature and age-related maturity of fat. 16 Only cases evaluated with standard STIR (constant TI, 85 milliseconds) images of diagnostic quality were included in this report for consistency, and cases with obvious fat suppression deficiency for any reason were excluded. There was probably less trabecular fat T1 relaxation time variation in our group of horses mainly composed of adult Warmbloods scanned in temperate zones, compared with young Thoroughbreds or horses scanned in tropical or polar zones.…”

Niederfeld-magnetresonanztomographische Untersuchung durchdringender Hufverletzungen bei 10 Pferden

“…• Short-Tau-Inversion-Recovery-Sequenz (STIR): sagittal Die Time of Repetition (TR) der STIR-Sequenzen, die zu einer optimalen Fettunterdrückung führte, wurde mithilfe eines sogenann-ten STIR-Tests bestimmt (1). Bei einigen Patienten wurden weitere Ebenen der angegebenen Sequenzen untersucht, teilweise auch zusätzliche, nicht aufgeführte Sequenzen.…”

Detection of early osteoarthritis in the centrodistal joints ofIcelandic horses: Evaluation of radiography and low‐field magnetic resonance imaging

“…Scans included sagittally‐aligned T1‐weighted (W) gradient echo (GRE), T2*W‐GRE, T2W fast spin echo (FSE) and short tau inversion recovery (STIR) FSE sequences and a dorsally aligned T1W‐GRE sequence (http://onlinelibrary.wiley.com/doi/10.1111/evj.12370/suppinfo). The STIR‐FSE sequence used had a relatively short inversion time following recommendations for tissue scanning at temperatures between refrigeration and room temperature . Images were transferred to a work station with DICOM viewing software (OsiriX v 4.1.2) d for evaluation.…”