T2 Relaxation Time Measurements Research Articles

Определение времени продольной релаксации текущей жидкости ядерно-магнитным спектрометром дифференциального типа

The necessity of simultaneous measurement of the longitudinal T1 and transverse T2 relaxation times for monitoring the state of the flowing liquid during the study in the range of flow rate q changes by at least two orders of magnitude has been substantiated. A new method for measuring T1 has been developed. For its implementation, the design of a differential nuclear magnetic spectrometer has been proposed, which makes it possible to measure T1 in the entire range of measurement of flow rate q. The results of experimental studies are presented.

P1604 T1 mapping in asymptomatic patients with extracardiac sarcoidosis

Abstract Funding Acknowledgements LQ1605 from the National Program of Sustainability II (MEYS CR) Introduction Sarcoidosis is a systemic granulomatous disease affecting in particular the respiratory tract. Estimated 5% of these patients have clinical symptoms of heart involvement. Real number of patients with cardiac sarcoidosis is thought to be higher (around 20-30%), because the granulomatous process is sometimes asymptomatic. Cardiac magnetic resonance (CMR) including T1 relaxation time measurement could potentially detect early asymptomatic stadia of sarcoidosis of the heart. Purpose The aim of this study was to assess T1 mapping in detection of early cardiac involvement in asymptomatic patients with sarcoidosis. Methods One hundred twenty patients with sarcoidosis of the respiratory tract and/or extrapulmonary sarcoidosis and without any heart disease history were included. One hundred thirteen of them underwent CMR examination at 3,0 MR scanner. Cine images for assessment of left ventricular (LV) volumetric and functional parameters, and pre- and post-contrast Saturation method using adaptive recovery times for cardiac T1 mapping (SMART1map) and Modified Look-Locker Inversion recovery (MOLLI) images were acquired for assessment of native T1 relaxation time and extracellular volume (ECV). The measured parameters were compared between sarcoidosis patients and 22 healthy controls. Results Sarcoidosis patients had not enlarged LV (end-diastolic volume 119 ± 24ml vs 97 ± 20ml, p = NS) and normal global and regional systolic LV function – LV ejection fraction (EF) 65 ± 5% vs 66 ± 7% (p = NS). Mean native T1 relaxation time was not prolonged - 1464 ± 93 msec vs 1482 ± 88msec (p = NS) measured by SMART1map and 1317 ± 60 msec vs 1313 ± 83msec (p = NS) measured using MOLLI sequence. Similarly, mean ECV value was not increased - 16,3 ± 3,4% vs 17,9 ± 3,7% (p = NS) measured by SMART1map and 30,9 ± 2,9msec vs 30,7 ± 5,0% (p = NS) measured using MOLLI sequence. Conclusion Myocardial native T1 relaxation time was not prolonged and ECV was not increased in asymptomatic patients with extracardiac sarcoidosis.

Value of adding a T2 mapping sequence to a routine MR imaging protocol in evaluation of articular cartilage of the knee joint

Background: Magnetic resonance imaging (MRI) allows direct visualization of all tissues of the knee joint, including the articular cartilage with direct evaluation of chondral lesions. Beyond the morphological evaluation, MRI allows to characterize the structural organization (collagen network) and the matrix content of the cartilage. Such a quantitative approach may be performed in clinical practice by T2 mapping technique which can be used as early biomarker for knee osteoarthritis. T2 relaxation time measurements reflect these pathophysiological changes. T2 mapping technique had recently shown its potentiality to evaluate the quality of the cartilage composition since the transversal relaxation time (T2) reflects the ability of proton molecule to move and to exchange energy inside the cartilaginous matrix. Each variation of matrix content (water, proteoglycan and collagen) or each modification of the organization of the collagen network can induce T2 variations. Objective: The primary purpose of this study was determine whether the addition of a T2 mapping sequence to a routine MR imaging protocol could or could not improve diagnostic performance in the detection of the articular cartilage lesions and early identification of the cartilage degeneration within the knee joint. Methods: The current study is a cross sectional study that was conducted at private radiology centres in cairo.in the period between September 2019 and December 2020. The study included 20 patients. 13 Males and7 Females with age range from 25 to 65 years (mean age 41.53 years). Complaining from knee pain after direct trauma or twisting. Routine knee MR images from all patients were assessed for gross articular lesion. Then mean T2 values are obtained and the T2 maps are generated and reviewed. Comparative data of the overall Diagnostic indices of conventional MRI and T2 mapping are taken. Results: The age of the study group ranged from 25 to 65 years (mean age 41.53 years). The male patients represented the majority of our cases. We noted that there was more affection of the left knee compared to the right one with regional differences in the T2 values were observed as higher T2 values in the medial compartments cartilage (weight-bearing) compared to lateral ones’ cartilage (non-weight-bearing). Cases can be categorized according to the site of pain which was correlated later to the T2 values as: 15% anterior 35% medial, 15% lateral and 35% global. Out of the 20 cases, 12/20 (60 %) cases presented by knee pain following direct trauma, and 8/20 (40 %) cases presented by knee pain following knee twisting. All cases underwent conventional MRI with complementary T2 mapping sequence. In this study, the sensitivity, specificity, and accuracy of the conventional MRI results are 82.3%, 100 %, and 85 %, respectively. While the sensitivity, specificity, and accuracy of the T2 mapping finding results are 100 %, 100 %, and 100 %, respectively. Conclusion: In this study The addition of a T2 mapping of the knee cartilage sequence to a routine MR knee protocol at 1.5 T improved sensitivity in the detection of cartilage lesions within the knee joint from 82.3 % to 100 %, with improvement of accuracy from 85 % to 100%. The improvement in sensitivity with use of the T2 maps was in the identification of early cartilage degeneration.

T2 mapping of the trapeziometacarpal joint and triangular fibrocartilage complex: a feasibility and reproducibility study at 1.5 T.

To assess the feasibility and reproducibility of T2 relaxation time measurements of the trapeziometacarpal joint (TM) and triangular fibrocartilage complex (TFCC) on healthy subjects at 1.5T MR. Thirty-four healthy volunteers underwent an axial oblique multislice multiecho spin-echo sequence of the wrist at 1.5T, with 10 of them having performed another MR scan on a different 1.5T scanner. Regions of interest were independently manually drawn by two musculoskeletal radiologists to include the cartilaginous part of the TM and TFCC. Intra-observer, inter-observer and inter-scanner reproducibility of T2 relaxation time measurements was tested using the Bland-Altman method. The mean T2 values obtained by the two radiologists were 29.9 ± 6.5ms and 30.0 ± 6.1ms in the TM and 24.5 ± 2.3ms and 24.6 ± 2.8ms in the TFCC, respectively. The mean values of the second series of T2 measurements obtained by the senior radiologist were 29.9 ± 6.5ms and 30.0 ± 6.3ms in the TM and 24.3 ± 2.9ms in the TFCC. Inter-observer reproducibility in the TM and in the TFCC was 76% and 82%, respectively. Intra-observer reproducibility in the TM and TFCC was 71% and 76%, respectively. Inter-scanner reproducibility of T2 measurements was 36% in the TM and 85% in the TFCC, respectively. The assessment of T2 relaxation time measurements of the cartilage of the TM and the TFCC seems to be feasible and reproducible, although the inter-scanner reproducibility of T2 measurements of the TM is suboptimal. Further studies including patients are warranted to prove the utility of this tool.

Early diagnosis of degenerative changes in the articular/fibrocartilaginous disc of the temporomandibular joint in patients with temporomandibular disorders using delayed gadolinium-enhanced MRI at 3 Tesla – preliminary results

BackgroundDelayed gadolinium enhanced MRI of cartilage (dGEMRIC) is a quantitative method for assessment of glycosaminoglycan content in connective tissues. We hypothesize that the early diagnosis of degenerative changes in the temporomandibular joint could be diagnosed using dGEMRIC technique. PurposeTo test the compositional MRI technique, dGEMRIC, at 3 Tesla to diagnosis early the degenerative changes in the fibrocartilaginous disc of the temporomandibular joint (TMJ) in patients with temporomandibular disorders (TMD) and to compare the dGEMRIC index of patients to the healthy volunteers. MethodsSix volunteers (two men, four women; 20.8÷28.1 years) and eleven patients (22 TMJs, seven women, four men; 24÷54 years) were recruited for this prospective trial. Only patients with no morphological abnormality on MRI and without disc dislocations were included. Volunteers were used as a control group. The PD-weighted FSE sequence and the 3D GRE (DESS) sequence protocols were performed for morphological assessment. The Inversion recovery (IR) sequence was performed for T1 relaxation time measurements and intra-venous (IV) contrast agent administration was used according to the dGEMRIC protocol. T1 maps were calculated offline and ROIs were drawn on TMJ discs by a specialist trained in TMD disorders. Statistical evaluation was performed by ANOVA and correlations were calculated. ResultsThe difference between the dGEMRIC values in the TMJ articular discs of the patients and the volunteers was statistically significant (P = .019). After contrast agent administration the T1 values dropped in both groups. In patient group was the T1 drop stronger (−54% from initial pre-contrast value), while in control group was the T1 drop less pronounced (−46% from initial pre-contrast value). ConclusionsdGEMRIC seems to be a useful, compositional, quantitative method, suitable also for small joints, such as the articular disc of the TMJ. The results of the dGEMRIC index in the articular disc of the TMJ imply a lower GAG content in patients with TMJ disorders.

Monitoring the encapsulation of chlorin e6 derivatives into polymer carriers by NMR spectroscopy

The encapsulation of five derivatives of chlorin e6 with different hydrophobicity and aggregation properties into a series of five poloxamer-type triblock copolymer micelles (BCMs) with varying numbers of polyethylene and polypropylene glycol (PEG, PPG) units was monitored using 1H NMR spectroscopy. NMR chemical shift and line shape analysis, as well as dynamic methods including diffusion ordered spectroscopy (DOSY) and T1 and T2 relaxation time measurements of the chlorin and the polymer resonances, proved useful to assess the chlorin–BCM compatibility. The poloxamers had high capability to break up aggregates formed by chlorins up to intermediate hydrophobicity. Physically entrapped chlorins were always localized in the BCM core region. The loading capacity correlated with chlorin polarity for all poloxamers among which those with the lowest number of PPG units were most efficient. DOSY data revealed that relatively weakly aggregating chlorins partition between the aqueous bulk and micellar environment whereas more hydrophobic chlorins are well retained in the BCM core region, rendering these systems more stable. T1 and T2 relaxation time measurements indicated that motional freedom in the BCM core region contributes to encapsulation efficiency. The BCM corona dynamics were rather insensitive towards chlorin entrapment except for the poloxamers with short PEG chains. The presented data demonstrate that 1H NMR spectroscopy is a powerful complementary tool for probing the compatibility of porphyrinic compounds with polymeric carriers such as poloxamer BCMs, which is a prerequisite in the development of stable and highly efficient drug delivery systems suitable for medical applications like photodynamic therapy of tumors.

Volumetric multicomponent T1ρ relaxation mapping of the human liver under free breathing at 3T.

To develop a 3D sequence for T1ρ relaxation mapping using radial volumetric encoding (3D-T1ρ -RAVE) and to evaluate the multi relaxation components in the liver of healthy controls and chronic liver disease (CLD) patients. Fat saturation and T1ρ preparation modules were followed by a train of gradient-echo acquisitions and T1 restoration delay. The series of T1ρ -weighted images were fitted using mono-exponential, bi-exponential, and stretched-exponential models. The repeatability and reproducibility of the proposed technique were evaluated on National Institute of Standards and Technology phantom by calculating the coefficient of variation between test-retest scans on the same scanner and between two different 3T scanners, respectively. Mann-Whitney U-test was performed to assess differences in T1ρ components among patients (n = 3) and a control group (n = 10). The phantom study showed an error of 8.9% and 11.5% in mono T2 relaxation time measurement relative to the reference on 2 different scanners. The coefficient of variation for test-retest scans performed on the same scanner was 5.7% and 2.4% for scans performed on 2 scanners. The comparison between healthy controls and CLD patients showed a significant difference (P < .05) in mono relaxation time (P = .002), stretched-exponential relaxation parameter (P = .04). The Akaike information criteria C criterion showed 2.53 ± 0.9% (2.3 ± 0.3% for CLD) of the voxels are bi-exponential while in 65.3 ± 5.8% (81.2 ± 0.06% for CLD) of the liver voxels, the stretched-exponential model was preferred. The 3D-T1ρ -RAVE sequence allows volumetric, multicomponent T1ρ assessment of the liver during free breathing and can distinguish between healthy volunteers and CLD patients.

T2 mapping of the extraocular muscles in healthy volunteers: preliminary research on scan-rescan and observer-observer reproducibility.

T2-mapping technique and derived T2 relaxation time allows quantitative assessment of extraocular muscles; however, the reproducibility of T2 mapping-derived parameters was seldom studied till now. To evaluate the scan-rescan and observer-observer reproducibility of T2 relaxation time measurements of extraocular muscles in young healthy volunteers. Fourteen volunteers underwent T2-mapping examinations of the extraocular muscles three times within one month on a 3.0-T MR system. Scan-rescan and observer-observer reproducibility of T2 relaxation time measurements of the extraocular muscles were assessed using intraclass correlation coefficient and coefficient of variation. Both scan-rescan (short-term and long-term) and observer-observer could achieve good to excellent reproducibility, while better short-term than long-term scan-rescan reproducibility was obtained. The coefficient of variation of the T2 relaxation time of each extraocular muscles during both scan-rescan and observer-observer reproducibility assessment were <6%. T2 relaxation time measurement of the extraocular muscles is proven to be highly reproducible at 3.0 T. T2 mapping may be a potential imaging technique in the diagnosis and follow-up of orbital diseases involved extraocular muscles in further studies.

Infrapatellar fat pad abnormalities are associated with a higher inflammatory synovial fluid cytokine profile in young adults following ACL tear

To evaluate the degree of knee fat pad abnormalities after acute anterior cruciate ligament (ACL) tear via magnetic resonance fat pad scoring and to assess cross-sectionally its association with synovial fluid biomarkers and with early cartilage damage as quantified via T1ρ and T2 relaxation time measurements. 26 patients with acute ACL tears underwent 3T MR scanning of the injured knee prior to ACL reconstruction. The presence and degree of abnormalities of the infrapatellar (IPFP) and the suprapatellar (SPFP) fat pads were scored on MR images along with grading of effusion-synovitis and synovial proliferations. Knee cartilage composition was assessed by 3T MR T1ρ and T2 mapping in six knee compartments. We quantified concentrations of 20 biomarkers in synovial fluid aspirated at the time of ACL reconstruction. Spearman rank partial correlations with adjustments for age and gender were employed to evaluate correlations of MR, particularly cartilage composition and fat pad abnormalities, and biomarker data. The degree of IPFP abnormality correlated positively with the synovial levels of the inflammatory cytokine markers IFN-γ (ρpartial=0.64, 95% CI (0.26-0.85)), IL-10 (ρpartial=0.47, 95% CI (0.04-0.75)), IL-6 (ρpartial=0.56, 95% CI (0.16-0.81)), IL-8 (ρpartial=0.49, 95% CI (0.06-0.76)), TNF-α (ρpartial=0.55, 95% CI (0.14-0.80)) and of the chondrodestructive markers MMP-1 and -3 (MMP-1: ρpartial=0.57, 95% CI (0.17-0.81); MMP-3: ρpartial=0.60, 95% CI (0.21-0.83)). IPFP abnormalities were significantly associated with higher T1ρ and T2 values in the trochlear cartilage (T1ρ: ρpartial=0.55, 95% CI (0.15-0.80); T2: ρpartial=0.58, 95% CI (0.18-0.81)) and with higher T2 values in the medial femoral, medial tibial as well as in patellar cartilage (0.45≤ρpartial≤0.59). Correlations between SPFP abnormalities and synovial markers were not significant except for IL-6 (ρpartial=0.57, 95% CI (0.17-0.81)). This exploratory study suggests that acute ACL rupture can be associated with damage to knee tissues such as the inferior fat pad of the knee. Such fat pad injury could be partially responsible for the apparent post-injury pro-inflammatory response noted in ACL-injured individuals. However, future longitudinal studies are needed to link ACL-rupture associated fat pad injury with important patient outcomes such as the development of posttraumatic osteoarthritis.

Application of a Fast NMR T1 Relaxation Time Measurement to Sedimentary Rock Cores

Application of a Fast NMR T1 Relaxation Time Measurement to Sedimentary Rock Cores

Volume-localized measurement of oxygen extraction fraction in the brain using MRI.

PurposeT2‐relaxation‐under‐spin‐tagging (TRUST) is an MR technique for the non‐invasive assessment of whole‐brain cerebral oxygen extraction fraction (OEF), through measurement of the venous blood T2 relaxation time in the sagittal sinus. A key limitation of TRUST, however, is the lack of spatial specificity of the measurement. We sought to develop a modified TRUST sequence, selective localized TRUST (SL‐TRUST), having sensitivity to venous blood T2 within a targeted brain region, and therefore achieving spatially localized measurements of cerebral tissue OEF, while still retaining acquisition in the sagittal sinus.MethodsA method for selective localization of TRUST sequence was developed, and the reproducibility of the technique was evaluated in healthy participants. Regional measurements were achieved for a single hemisphere and for a 3D‐localized 70 × 70 × 80 mm3 tissue region using SL‐TRUST and compared to a global TRUST measure. An additional measure of venous blood T1 in the sagittal sinus was used to estimate subject‐specific hematocrit. Six subjects were scanned over 4 sessions, including intra‐session repeat measurements.ResultsThe average T2 in the sagittal sinus was found to be 60.8 ± 8.9, 62.7 ± 7.9, 64.6 ± 8.4, and 66.3 ± 10.3 ms (mean ± SD) for conventional TRUST, global SL‐TRUST, hemispheric SL‐TRUST, and 3D‐localized SL‐TRUST, respectively. Intra‐, inter‐session, and inter‐subject coefficients of variation for OEF using SL‐TRUST were found to be comparable and in some cases superior to those obtained using TRUST.ConclusionOEF comparison of 2 contralateral regions was achievable in under 5 min suggesting SL‐TRUST offers potential for quantifying regional OEF differences in both healthy and clinical populations.

T2 relaxation time measurements in tibiotalar cartilage after barefoot running and its relationship to ankle biomechanics

The influence of ankle kinematics and plantar pressure from mid-range barefoot running on T2 relaxation times of tibiotalar cartilage is unknown. This study aimed to quantitatively evaluate the T2 relaxation time of tibiotalar cartilage and ankle biomechanics following 5 km barefoot running. Twenty healthy runners (who had no 5 km barefoot running experience) underwent 3.0-Tesla magnetic resonance (MR) scans and assessment of running gait before and after 5 km barefoot running. Participants were divided into two groups consisting of marathon-experienced (n = 10) and novice (n = 10) with equal number of males and females in each group. Three musculoskeletal radiologists measured T2 relaxation times in 18 regions of the ankle cartilage: anterior zone, central zone, and posterior zone, or lateral, middle, and medial sections in the sagittal plane. Three-dimensional ankle kinetics, kinematics, and plantar pressure were all also assessed during barefoot running. In the novice group, the T2 relaxation time in the posterior zone of tibial cartilage (p = 0.001) and lateral section in both tibial (p = 0.02) and talar (p = 0.02) cartilage were significantly increased after barefoot running. Ankle kinematics exhibited significant changes in females. Plantar loading was shifted from the medial to lateral aspect after running. This included a significant reduction in the loading under the toes and the 1st, 2nd and 3rd metatarsals, with a significant increase under the 4th and 5th metatarsals and lateral midfoot. The results suggest that plantar pressure may directly lead to local increases in cartilage T2 signal, which was not associated with changes in ankle kinematics.

Application of Magnetic Resonance to Assess Lyophilized Drug Product Reconstitution

PurposeDynamic in-situ proton (1H) magnetic resonance imaging (MRI) and 1H T2-relaxometry experiments are described in an attempt to: (i) understand the physical processes, that occur during the reconstitution of lyophilized bovine serum albumin (BSA) and monoclonal antibody (mAb) proteins; and (ii) objectify the reconstitution time.MethodsRapid two-dimensional 1H MRI and diffusion weighted MRI were used to study the temporal changes in solids dissolution and characterise water mass transport characteristics. One-shot T2 relaxation time measurements were also acquired in an attempt to quantify the reconstitution time. Both MRI data and T2-relaxation data were compared to standard visual observations currently adopted by industry. The 1H images were further referenced to MRI calibration data to give quantitative values of protein concentration and, percentage of remaining undissolved solids.ResultsAn algorithmic analysis of the 1H T2-relaxation data shows it is possible to classify the reconstitution event into three regimes (undissolved, transitional and dissolved). Moreover, a combined analysis of the 2D 1H MRI and 1H T2-relaxation data gives a unique time point that characterises the onset of a reconstituted protein solution within well-defined error bars. These values compared favourably with those from visual observations. Diffusion weighted MRI showed that low concentration BSA and mAb samples showed distinct liquid-liquid phase separation attributed to two liquid layers with significant density differences.ConclusionsT2 relaxation time distributions (whose interpretation is validated from the 2D 1H MR images) provides a quick and effective framework to build objective, quantitative descriptors of the reconstitution process that facilitate the interpretation of subjective visual observations currently adopted as the standard practice industry.

3414 Association of blood pressure and biochemical knee cartilage composition assessed by T2 relaxation time measurements: Data from the Osteoarthritis Initiative

OBJECTIVES/SPECIFIC AIMS: The goal of this study was to investigate the associations of systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse pressure (PP) with knee articular cartilage composition using magnetic resonance imaging (MRI)-based T2 relaxation time measurements in study participants from the Osteoarthritis Initiative (OAI). METHODS/STUDY POPULATION: In this longitudinal study, 1,139 participants from the OAI, a multi-center, observational study of the evolution of knee OA, were selected using the following inclusion criteria: right knee Kellgren Lawrence (KL) score (radiographic classification of OA severity) 0-2 indicating no to mild radiographic OA at baseline, no history of rheumatoid arthritis at baseline, available blood pressure measurements at baseline, available T2 measurements in at least three knee compartments at baseline and 48-month follow-up. Linear regression models were performed using standardized values for SBP, DBP and PP as primary predictors and change in cartilage T2 over 48 months, a measure of cartilage matrix quality and degeneration, as the primary outcome. PP was defined as SBP minus DBP. Change in superficial layer and deep layer cartilage T2, which reflect differences in the laminar organization of knee cartilage T2, were also included as outcomes. Statistical models were adjusted for common risk factors for knee OA (baseline age, sex, BMI, KL score) as well as number of currently used anti-hypertensive medications (AHM) reported at baseline. We included AHMs whose primary indication was the treatment of hypertension including beta blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARB), thiazides, chlorthalidone, dihydropyridine calcium channel blockers (CCB) and aliskiren. All predictors, outcomes and covariates (except sex) were analyzed as continuous variables. We included interaction terms in the models to evaluate whether the covariates (age, sex, BMI, KL score, number of AHMs) modified the association of SBP, DBP and PP with cartilage T2. RESULTS/ANTICIPATED RESULTS: The average age of all study participants was 58.8 years (SD ± 8.6) with a higher proportion of men (59.4%), average body mass index (BMI) was 28.3 (SD ± 4.5), average SBP was 122.4 (SD ± 15.4) mmHg, average DBP was 75.5 (SD ± 9.6) mmHg and 469 (38.1%) study participants were taking at least one AHM. Higher baseline DBP was significantly associated with a faster increase in global T2 (0.22 [0.10,0.35], P &lt; 0.001), global deep layer T2 (0.20 [0.03,0.36], P &lt; 0.022) and global superficial layer T2 (0.39 [0.20,0.58], P &lt; 0.001). These associations were significant in both unadjusted and the models adjusted for age, sex, BMI and KL score. No significant associations were found between SBP or PP and cartilage T2 and no significant interactions were found between SBP, DBP, PP and the covariates. DISCUSSION/SIGNIFICANCE OF IMPACT: Higher baseline DBP was associated with a faster increase in knee cartilage T2, suggesting accelerated cartilage degeneration. This association was stronger for the superficial layer of knee cartilage T2 compared to the deep layer. Although further basic mechanistic studies are needed to elucidate the underlying pathophysiology of this relationship, these results suggest lowering DBP may influence knee OA.

NMR relaxometry in the investigation of the kinetics of the recrystallization of felodipine

The method of Nuclear Magnetic Resonance (NMR) relaxometry is proposed to be applied to investigate the kinetics of the recrystallization of a substance from the amorphous phase. The method is based on the determination and analysis of nuclear magnetization recovery Mz obtained from spin-lattice T1 relaxation time measurements as a function of time since sample amorphization. The formation of a biphasic (crystalline and amorphous) system in the process of recrystallization implies that the magnetization recovery Mz is biexponential and that the amplitudes of its components are proportional to the number of spins (protons) in the crystalline and amorphous phases, and, thus, also to the volume occupied by the phases. The method was tested for amorphous felodipine samples with grain sizes close to 0.1 or 1 mm, and the recrystallization process was confirmed by using Powder X-ray Diffraction (PXRD) and Fourier-Transform Infrared (FTIR) methods. Qualitative comparison of the results obtained with the data obtained earlier by PXRD and Raman methods for felodipine samples with grain sizes of 0.2 and 0.6 mm [U. S. Kestur, I. Ivanesivic, D. E. Alonzo, L. S. Taylor, Influence of particle size on the crystallization kinetics of amorphous felodipine powders, Powder Technology 236 (2013) 197–204] showed reasonable agreement. The method is fully extensive and can be applied to amorphous samples prepared in different ways, such as grinding, milling or melting, as well as for co-amorphous or amorphous solid dispersion samples.

Quantitative T2-mapping using MRI for detection of prostate malignancy: a systematic review of the literature.

Quantitative T2-mapping using magnetic resonance imaging (MRI) allows measurement of tissue T2-relaxation times to complement anatomical and spatial information derived from T2-weighted imaging. Studies have shown varying T2-relaxation times between prostate malignancy and non-malignant prostatic tissue. This paper aims to critically review the literature in a systematic review, to determine the usefulness of T2-mapping in the evaluation of prostate malignancy. A literature search of PubMed and Embase databases was performed. There were 17 studies, up to 31 June 2018, that measured T2-relaxation times of prostate cancer and non-malignant prostatic tissue. Data reviewed from each study included: number of patients and regions of interest evaluated; patient age; study design; T2-mapping technique utilized; reported T2-relaxation values; method of data analysis; method of “ground-truth” assessment; and reported limitations. The T2-relaxation times of prostate cancer and non-malignant prostatic tissue were compared. The T2-relaxation times in the transition zone (TZ) are generally lower than the peripheral zone (PZ). The T2-relaxation times in prostate malignancy are significantly lower than normal PZ in all the studies that performed a statistical comparison. In three out of four studies that performed a statistical comparison, there was no significant difference in the T2-relaxation times between prostate malignancy and non-malignant TZ. T2-mapping appears useful in identifying prostate malignancy in the peripheral zone but is unable to reliably distinguish prostate malignancy and non-malignant transition zone. Further studies are recommended to determine if T2-mapping can improve diagnostic accuracy when used in conjunction with multiparametric MRI for detection of prostate malignancy.

Precision of T1-relaxation time measurements in the hepatic portal vein: influence of measurement technique and sequence parameters.

To investigate the effects of a range of parameter settings on T1 measurement stability in the portal vein using the T1-mapping sequences Look-Locker (LL) and Modified Look-Locker inversion recovery (MOLLI). Ten different versions of LL and MOLLI sequences were tested and compared to a reference sequence provided by the MR manufacturer. Ten healthy volunteers were imaged multiple times on two separate scan days at 3T. The mean T1 values and coefficient of variation (CoV) were calculated for each of the ten sequences and compared to the reference sequence. Six of the tested sequences had T1 values close to the reference sequence; among those, three sequences achieved lower CoV than the reference sequence. Lowest CoV was achieved using a non-triggered LL sequence with 5beat readout and a 45o flip angle (mean T1 1733ms ± 89ms, CoV 1.3% ± 0.58%). T1-measurements in the hepatic portal vein can be performed with high precision using either MOLLI or LL sequences provided that LL sampling duration is sufficiently long and flip angle sufficiently high. The advantage of constant timing outweighed the advantage of ECG-triggering.

The usefulness of relaxation time using MRI measurements

Introduction. Magnetic Resonance Imaging methods are now frequently used for the analysis of the diseased tissue. These methods are based on the fact that the spin-lattice, T1, and the spin-spin, T2, relaxation times are different in diseased tissue as compared to that of normal tissue. Aim. Here we present measurements of spin-lattice relaxation time T1 on a Magnetic Resonance Imaging scaner with field strength 1.5 Tesla. Material and methods. Measurements of T1 relaxation time and analysis of literature. Results. We provide procedure for measurements of T1 relaxation time with field strength 1.5 Tesla and present a discussion of current applications.

Cartilage repair surgery prevents progression of knee degeneration.

To investigate, whether cartilage repair surgery for focal osteochondral defects at the knee results in less degenerative changes over 6years in a MR imaging follow-up than morphologically initially identical defects in non-operated control subjects from the osteoarthritis initiative (OAI). A total of 32 individuals received baseline and follow-up MRI. In n = 16 patients with cartilage repair [osteochondral autograft transfer system (OATS), n = 12; spongiosa-augmented matrix-associated autologous chondrocyte implantation (MACI), n = 4] MRI was performed preoperatively and after 5.7 ± 2.3year follow-up. Baseline MRIs of non-operated subjects from the OAI were screened for initially identical cartilage defects (n = 16). Morphological knee abnormalities were assessed using WORMS, AMADEUS and MOCART scores. A sagittal 2D MSME sequence was implemented for quantitative cartilage T2 relaxation time measurements in all (0, 2, 4, 6 and 8-years) follow-ups from the OAI and in the postoperative MRI protocol. For both groups, focal osteochondral defects were located at the femoral condyle in 8/16 cases (5 medial, 3 lateral) and at the patella in 8/16 cases. At baseline, the mean cartilage defect size ± SD was 1.4 ± 1.3cm2 for the control group and 1.3 ± 1.2cm2 for the cartilage repair group (n.s.). WORMS scores were not significantly different between the cartilage repair group and the control group at baseline [mean difference ± SEM (95%CI); 0.5 ± 2.5 (- 4.7, 5.7), n.s.]. During identical follow-up times, the progression of total WORMS scores [19.9 ± 2.3 (15.0, 24.9), P < 0.001] and of cartilage defects scores in the affected (P < 0.001) and in the opposing (P = 0.029) compartment was significantly more severe in non-operated individuals (P < 0.05). In non-operated subjects, T2 values increased continuously from baseline to the 8-year follow-up (P = 0.001). Patients with cartilage repair showed less progression of degenerative MRI changes at 6-year follow-up than a control cohort from the OAI with initially identical osteochondral defects. Patients with focal cartilage defects may profit from cartilage repair surgery since it may prevent progression of early osteoarthritis at the knee joint. Prognostic study, Level II.

Ultra-short echo time imaging with multiple echo refocusing for porous media T2 mapping.

T2 relaxation time measurement is a powerful tool to distinguish signal components in porous media. As T2 weighting is generally achieved by spin-echo based methods, it is very challenging to capture very short T2 relaxation time components, approximately 1 ms, with high resolution spatial encoding. It is especially challenging when T2 relaxation times of the other signal components are not known a priori. We propose a method, combining ultrashort echo time (UTE) imaging with multiple spin echo refocusing, to generate a series of images with T2 weighting. The T2 decay curves for each image voxel were extracted, and multiple T2 relaxation components were quantitatively evaluated. The method has been applied to a fast relaxation system, namely, moisture content in wood samples to differentiate cell wall (bound) water and cell cavity (lumen) water.