Cartilage T1ρ and T2 relaxation times: longitudinal reproducibility and variations using different coils, MR systems and sites.

OBJECTIVE: To evaluate the longitudinal reproducibility and variations of cartilage T1ρ and T2 measurements using different coils, MR systems and sites. METHODS: Single-Site study: Phantom data were collected monthly for up to 29 months on four GE 3T MR systems. Data from phantoms and human subjects were collected on two MR systems using the same model of coil; and were collected on one MR system using two models of coils. Multi-site study: Three participating sites used the same model of MR systems and coils, and identical imaging protocols. Phantom data were collected monthly. Human subjects were scanned and rescanned on the same day at each site. Two traveling human subjects were scanned at all three sites. RESULTS: Single-Site Study: The phantom longitudinal RMS-CVs ranged from 1.8% to 2.7% for T1ρ and 1.8-2.8% for T2. Significant differences were found in T1ρ and T2 values using different MR systems and coils. Multi-Site Study: The phantom longitudinal RMS-CVs ranged from 1.3% to 2.6% for T1ρ and 1.2-2.7% for T2. Across three sites (n = 16), the in vivo scan-rescan RMS-CV was 3.1% and 4.0% for T1ρ and T2, respectively. Phantom T1ρ and T2 values were significantly different between three sites but highly correlated (R > 0.99). No significant difference was found in T1ρ and T2 values of traveling controls, with cross-site RMS-CV as 4.9% and 4.4% for T1ρ and T2, respectively. CONCLUSION: With careful quality control and cross-calibration, quantitative MRI can be readily applied in multi-site studies and clinical trials for evaluating cartilage degeneration.

Correlation of meniscal T2* with multiphoton microscopy, and change of articular cartilage T2 in an ovine model of meniscal repair.

OBJECTIVE: To correlate meniscal T2* relaxation times using ultra-short echo time (UTE) magnetic resonance imaging (MRI) with quantitative microscopic methods, and to determine the effect of meniscal repair on post-operative cartilage T2 values. DESIGN: A medial meniscal tear was created and repaired in the anterior horn of one limb of 28 crossbred mature ewes. MR scans for morphological evaluation, meniscal T2* values, and cartilage T2 values were acquired at 0, 4 and 8 months post-operatively for the Tear and Non-Op limb. Samples of menisci from both limbs were analyzed using multiphoton microscopy (MPM) analysis and biomechanical testing. RESULTS: Significantly prolonged meniscal T2* values were found in repaired limbs than in control limbs, P < 0.0001. No regional differences of T2* were detected for either the repaired or control limbs in the anterior horn. Repaired limbs had prolonged cartilage T2 values, primarily anteriorly, and tended to have lower biomechanical force to failure at 8 months than Non-Op limbs. MPM autofluorescence and second harmonic generation data correlated with T2* values at 8 months (ρ = -0.48, P = 0.06). CONCLUSIONS: T2* mapping is sensitive to detecting temporal and zonal differences of meniscal structure and composition. Meniscal MPM and cartilage T2 values indicate changes in tissue integrity in the presence of meniscal repair.

Imaging near metal with a MAVRIC-SEMAC hybrid.

The recently developed multi-acquisition with variable resonance image combination (MAVRIC) and slice-encoding metal artifact correction (SEMAC) techniques can significantly reduce image artifacts commonly encountered near embedded metal hardware. These artifact reductions are enabled by applying alternative spectral and spatial-encoding schemes to conventional spin-echo imaging techniques. Here, the MAVRIC and SEMAC concepts are connected and discussed. The development of a hybrid technique that utilizes strengths of both methods is then introduced. The presented technique is shown capable of producing minimal artifact, high-resolution images near total joint replacements in a clinical setting.

Short-term repeatability of joint space width measurements using a magnetic resonance imaging compatible knee positioning device.

The purpose of this study was to evaluate a magnetic resonance imaging (MRI) compatible knee positioning device to aid in minimizing intratechnologist and intertechnologist differences of minimum joint space width (JSW) measurements. Five subjects were scanned by two separate technologists, with and without an MRI-compatible positioning device. A semi-automated program calculated the minimum JSW of the tibiofemoral and patellofemoral joints. The scan-to-scan repeatability was evaluated from measurements between serial scans without subject repositioning, and the intratechnologist and intertechnologist repeatabilities were evaluated when the subject was removed from the magnet and repositioned by an individual technologist. The root mean square (RMS) error of the JSW measurements was also calculated. All measures of scan-to-scan repeatability and intratechnologist repeatability were unchanged with the MRI-compatible positioning device. The intertechnologist repeatability decreased from 0.70 to 0.42 mm, and the RMS error was significantly reduced (P = 0.0006) from 0.26 to 0.15 mm for the tibiofemoral joint. The variability of patellofemoral JSW measurements increased when using the positioning device; however, the increases were not statistically significant. The intertechnologist repeatability increased from 1.55 to 1.79 mm, and the RMS error increased from 0.58 to 0.73 mm. The MRI-compatible positioning device was successful at reducing JSW measurement variability at the tibiofemoral joint. The increase in measurement variability at the patellofemoral joint may be due to local incongruities of the articular surfaces. An MRI-compatible positioning device may be beneficial for quantitative longitudinal studies evaluating knee joint health.

Quantitative magnetic resonance imaging and histological hoof wall assessment of 3-year-old Quarter Horses.

BACKGROUND: Few noninvasive methods are available for equine hoof wall evaluation. The highly organised wall structures and composition of proteoglycans and collagens may make this region amenable to quantitative MRI (qMRI) techniques of T1ρ and T2 mapping to identify pathology related to proteoglycan content and collagen organisation respectively. OBJECTIVE: To establish normative T1ρ and T2 values of the equine hoof wall of 3-year-old Quarter Horses with histological comparison. STUDY DESIGN: Cadaveric anatomical study. METHODS: Six cadaveric left thoracic feet from 3-year-old racing Quarter Horses with no reported lameness were evaluated using T1ρ and T2 mapping. Mapping was performed at six regions of interest at the toe of each hoof including proximal and distal regions of the inner epidermis, stratum lamellatum and corium. Histology was evaluated for standard hoof morphology and proteoglycan staining. RESULTS: T2 values of the stratum lamellatum and corium were similar (42.9 [95% CI: 41.6-44.2] ms and 44 [95% CI: 42.7-45.3] ms respectively), but both were significantly different to the inner epidermis (35.8 [95% CI: 34.5-37.1] ms, P<0.001). T1ρ values for the inner epidermis, stratum lamellatum and corium were significantly different (25.1 [95% CI: 23.1-27.1] ms, 44.4 [95% CI: 42.4-46.4] ms and 50.1 [95% CI: 48.1-52.1] ms, respectively, P<0.001). Histology demonstrated normal organised morphology. Proteoglycan staining was only visible in the stratum lamellatum and corium. MAIN LIMITATIONS: Cadaveric study with frozen samples used. CONCLUSIONS: Variation of qMRI metrics through the depth of the equine hoof wall was found. Although the highly ordered environment of collagen may contribute to T2 values, there was lack of evidence to support proteoglycan content as a major contributor of T1ρ values. It is possible T1ρ values had a greater dependence on total water content as the lowest values were seen in the epidermis. Additional research using qMRI is needed to determine mapping values in different disease states.

Magnetic resonance imaging of an equine fracture model containing stainless steel metal implants.

REASONS FOR PERFORMING STUDY: Post operative imaging in subjects with orthopaedic implants is challenging across all modalities. Magnetic resonance imaging (MRI) is preferred to assess human post operative musculoskeletal complications, as soft tissue and bones are evaluated without using ionising radiation. However, with conventional MRI pulse sequences, metal creates susceptibility artefact that distorts anatomy. Assessment of the post operative equine patient is arguably more challenging due to the volume of metal present, and MRI is often not performed in horses with implants. Novel pulse sequences such as multiacquisition variable resonance image combination (MAVRIC) now provide improved visibility in the vicinity of surgical-grade implants and offer an option for imaging horses with metal implants. OBJECTIVES: To compare conspicuity of regional anatomy in an equine fracture-repair model using MAVRIC, narrow receiver bandwidth (NBW) fast spin echo (FSE), and wide receiver bandwidth (WBW) FSE sequences. STUDY DESIGN: Nonrandomised in vitro experiment. METHODS: MAVRIC, NBW FSE and WBW FSE were performed on 9 cadaveric distal limbs with fractures and stainless steel implants in the third metacarpal bone and proximal phalanx. Objective measures of artefact reduction were performed by calculating the total artefact area in each transverse image as a percentage of the total anatomic area. The number of transverse images in which fracture lines were visible was tabulated for each sequence. Regional soft tissue conspicuity was assessed subjectively. RESULTS: Overall anatomic delineation was improved using MAVRIC compared with NBW FSE; delineation of structures closest to the metal implants was improved using MAVRIC compared with WBW FSE and NBW FSE. Total artefact area was the highest for NBW FSE and lowest for MAVRIC; the total number of transverse slices with a visible fracture line was highest in MAVRIC and lowest in NBW FSE. CONCLUSION: MAVRIC and WBW FSE are feasible additions to minimise artefact around implants.

Topical DMSO treatment for pegylated liposomal doxorubicin-induced palmar-plantar erythrodysesthesia.

PURPOSE: Chemotherapeutic regimens that utilize fluorouracil, cytarabine, and doxorubicin have been shown to cause a dermatologic syndrome known as hand-foot syndrome, or palmar-plantar erythrodysesthesia syndrome (PPES). Pegylated liposomal doxorubicin has proven effective in the treatment of AIDS-related Kaposi's sarcoma, ovarian cancer refractory to platinum and paclitaxel therapies, and metastatic breast cancer. In a study of the treatment of refractory epithelial cell ovarian cancers with lipozomal doxorubicin utilizing intravenous doses of 50 mg/m(2) every 3 weeks, grade 3 PPES was observed in 29% of patients (10/35) and required dose reductions and/or dose delay after a median of three therapy cycles. METHODS: Current methods to prevent pegylated liposomal doxorubicin-induced PPES include dose reduction, lengthening of the drug administration interval and ultimately, drug withdrawal. Topical 99% dimethylsulfoxide (DMSO) also has shown strong activity in treating tissue extravasation reactions during intravenous administration of doxorubicin. RESULTS: Two patients undergoing chemotherapy with pegylated liposomal doxorubicin, 50 mg/m(2) every 4 weeks, developed grade 3 PPE after three cycles. Their PPES resolved over a period of 1 to 3 weeks while receiving topical 99% DMSO four times daily for 14 days. CONCLUSIONS: While these results are promising, patients must be treated in a prospective study of this topical DMSO formulation to definitively document its therapeutic efficacy.

Development and validation of a computational model of the knee joint for the evaluation of surgical treatments for osteoarthritis.

A three-dimensional (3D) knee joint computational model was developed and validated to predict knee joint contact forces and pressures for different degrees of malalignment. A 3D computational knee model was created from high-resolution radiological images to emulate passive sagittal rotation (full-extension to 65°-flexion) and weight acceptance. A cadaveric knee mounted on a six-degree-of-freedom robot was subjected to matching boundary and loading conditions. A ligament-tuning process minimised kinematic differences between the robotically loaded cadaver specimen and the finite element (FE) model. The model was validated by measured intra-articular force and pressure measurements. Percent full scale error between FE-predicted and in vitro-measured values in the medial and lateral compartments were 6.67% and 5.94%, respectively, for normalised peak pressure values, and 7.56% and 4.48%, respectively, for normalised force values. The knee model can accurately predict normalised intra-articular pressure and forces for different loading conditions and could be further developed for subject-specific surgical planning.

Clinical evaluation of T2 values of patellar cartilage in patients with osteoarthritis.

OBJECTIVE: The transverse relaxation time constant, T2, of articular cartilage has been proposed as a biomarker for osteoarthritis (OA). Previous studies have not clearly defined the relationship between cartilage T2 values and clinical methods of grading OA or known factors associated with OA. This study compared T2 values of patellar cartilage grouped by radiographic stage of patello-femoral OA and by body mass index (BMI). METHODS: T2 values of patellar cartilage were calculated for 113 subjects using images acquired on a 1.5 T clinical scanner. Radiographs of the patello-femoral joint were graded for OA grading using the Kellgren-Lawrence scale. RESULTS: No differences of T2 values were found across the stages of OA (P = 0.25), but the factor of BMI did have a significant effect (P < 0.0001) on T2 value. CONCLUSIONS: The results indicate the T2 values are not sensitive to changes in radiographic stages of OA. In addition, differences of T2 values with BMI signify structural changes occurring within the patello-femoral joint and that BMI may be considered a factor for a potential increase of T2 values. Future studies comparing different OA grading methods with T2 mapping may highlight the sensitivity of T2 mapping in a clinical setting.

Expression of transforming growth factor-alpha-like messenger ribonucleic acid transcripts in the bovine mammary gland.

The objective of this study was to evaluate the expression of mRNA for transforming growth factor-alpha in the bovine mammary gland. Total RNA from 23 cows at various stages of development was isolated from mammary parenchyma and subjected to Northern blot analysis using human transforming growth factor-alpha 32P-labeled deoxycytosine triphosphate cDNA probe. When blots were washed through 1x sodium chloride and sodium citrate plus 1% SDS at 60 degrees C, a 4.8-kb band was observed in all RNA samples. When stringency was increased to .1x, mRNA transcripts were observed only for cows at d 233, 240, and 244 of gestation. After the high stringency washes, major bands were observed at 7.4 and 3.3 kb and minor bands on d 233 at 5.4, 2.3, and 1.6 kb. No additional transcripts were detected in RNA from mammary glands of nonpregnant cows during involution, lactating cows, or estrogen-treated heifers. These data indicate that transcripts similar to transforming growth factor-alpha are present in the bovine mammary gland. The expression pattern could represent alternatively spliced transcripts that were produced during an important period of mammary development prior to parturition.

MedSpanish: a language tool for the emergency department.

Language barriers frequently impede the ability of the health care professional to provide the highest quality health care to his or her patients. Spanish speaking people are rapidly becoming the largest minority population in the United States. In order to facilitate access to appropriate medical care that would not be inhibited by miscommunication or lack of a trained translator, the MedSpanish Web Site was developed for use in the Emergency Department. The site contains common Spanish vocabularies, including translations and audio clips, that would be used in such a setting. The various sections are formatted so that they could easily become pocket cards rather than relying on the availability of a computer in a medical emergency. While MedSpanish is not designed to replace a trained translator, it does offer an effective alternative if such translations services are not available.