Use Of Dynamic Magnetic Resonance Imaging Research Articles

Dynamic magnetic resonance imaging of the pelvic floor: clinical application

Dynamic magnetic resonance imaging (MRI) of the pelvic floor plays akey role in imaging complex pelvic floor dysfunction. The simultaneous detection of multiple findings in acomplex anatomic setting renders correct analysis and clinical interpretation challenging. The most important aspects (anatomy of the pelvic floor, three compartment model, morphological and functional analysis, reporting) for asuccessful clinical use of dynamic MRI of the pelvic floor are summarized. Review of the scientific literature on dynamic pelvic MR imaging with special consideration of the joint recommendations provided by the expert panel of ESUR/ESGAR in 2016. The pelvic floor is acomplex anatomic structure, mainly formed by the levator ani muscle, the urethral support system and the endopelvic fascia. Firstly, morphological changes of these structures are analysed on the static sequences. Secondly, the functional analysis using the three compartment model is performed on the dynamic sequences during squeezing, straining and defecation. Pelvic organ mobility, pelvic organ prolapse, the anorectal angle and pelvic floor relaxation are measured and graded. The diagnosis of cystoceles, enteroceles, rectoceles, the uterovaginal as well as anorectal decent, intussusceptions and dyssynergic defecation should be reported using astructured report form. Acomprehensive analysis of all morphological and functional findings during dynamic MRI of the pelvic floor can provide information missed by other imaging modalities and hence alter therapeutic strategies.

Effect of Loading on In Vivo Tibiofemoral and Patellofemoral Kinematics of Healthy and ACL-Reconstructed Knees

Background: Although knees that have undergone anterior cruciate ligament reconstruction (ACLR) often exhibit normal laxity on clinical examination, abnormal kinematic patterns have been observed when the joint is dynamically loaded during whole body activity. This study investigated whether abnormal knee kinematics arise with loading under isolated dynamic movements. Hypothesis: Tibiofemoral and patellofemoral kinematics of ACLR knees will be similar to those of the contralateral uninjured control knee during passive flexion-extension, with bilateral differences emerging when an inertial load is applied. Study Design: Controlled laboratory study. Methods: The bilateral knees of 18 subjects who had undergone unilateral ACLR within the past 4 years were imaged by use of magnetic resonance imaging (MRI). Their knees were cyclically (0.5 Hz) flexed passively. Subjects then actively flexed and extended their knees against an inertial load that induced stretch-shortening quadriceps contractions, as seen during the load acceptance phase of gait. A dynamic, volumetric, MRI sequence was used to track tibiofemoral and patellofemoral kinematics through 6 degrees of freedom. A repeated-measures analysis of variance was used to compare secondary tibiofemoral and patellofemoral kinematics between ACLR and healthy contralateral knees during the passive and active extension phases of the cyclic motion. Results: Relative to the passive motion, inertial loading induced significant shifts in anterior and superior tibial translation, internal tibial rotation, and all patellofemoral degrees of freedom. As hypothesized, tibiofemoral and patellofemoral kinematics were bilaterally symmetric during the passive condition. However, inertial loading induced bilateral differences, with the ACLR knees exhibiting a significant shift toward external tibial rotation. A trend toward greater medial and anterior tibial translation was seen in the ACLR knees. Conclusion: This study demonstrates that abnormal knee kinematic patterns in ACLR knees emerge during a simple, active knee flexion-extension task that can be performed in an MRI scanner. Clinical Relevance: It is hypothesized that abnormal knee kinematics may alter cartilage loading patterns and thereby contribute to increased risk for osteoarthritis. Recent advances in quantitative MRI can be used to detect early cartilage degeneration in ACLR knees. This study demonstrates the feasibility of identifying abnormal ACLR kinematics by use of dynamic MRI, supporting the combined use of dynamic and quantitative MRI to investigate the proposed link between knee motion, cartilage contact, and early biomarkers of cartilage degeneration.

The Role of Dynamic Magnetic Resonance Imaging in the Evaluation of Pulmonary Nodules and Masses

Objective: The aim of our study was to determine whether or not dynamic magnetic resonance imaging (MRI) with kinetic and morphological parameters can reveal significant differences between malignant and benign pulmonary lesions, and thus to evaluate the use of dynamic MRI in the management of pulmonary nodules. Patients and Methods: Thirty-one patients (4 women and 27 men) underwent 1.5 T MRI, where 10 consecutive dynamic series were performed every 30 s by using 3D fast low-angle shot sequences. The percentage increase in the signal intensity of the lesions was determined for each time point. Time-enhancement curves of the lesions were drawn and classified into four types: A, B, C and D. Early peak (EP) and maximum peak (MP) values of the curves were calculated and compared with the diagnoses of the patients. The usefulness of these parameters was tested statistically. In addition to the comparison of the parameters between the groups, receiver-operating characteristic analysis was used to assess sensitivity, specificity, and both positive and negative predictive values of EP and MP parameters. Results: Of the 31 pulmonary lesions, 16 (52%) were malignant. These showed a stronger enhancement with higher median values of EP and MP (77.08 and 123.15, respectively) than those corresponding to the benign lesions (14.45 and 32.53, respectively). There were significant differences between the benign and malignant lesions (p < 0.001). Sensitivity, specificity, positive predictive value and negative predictive value were 75, 93, 92 and 78% for EP and 93, 86, 88 and 93% for MP, respectively. Conclusion: A combination of kinetic and morphological evaluation in dynamic MRI provided accurate differentiation between benign and malignant pulmonary lesions. It was a useful and noninvasive method of evaluating pulmonary nodules.

Quel bilan d’imagerie avant une radiothérapie de rattrapage après prostatectomie radicale pour adénocarcinome prostatique ?

Prostatectomy is one of the most widely used methods for treatment of adenocarcinoma of the prostate. According to anatomopathological criteria, between 10 and 40% of patients will display biochemical relapse in the absence of adjuvant radiotherapy. Anatomopathological and biochemical criteria are powerful tools for selecting patients for salvage radiotherapy. The aim of this article is to review literature on the latest progress in radiological and nuclear medicine techniques and their performance levels, in order to determine local, regional and metastatic relapses associated with the techniques and specify the radiotherapy target volume. Magnetic resonance imaging (MRI) displays the best sensitivity and specificity for examination of the prostate bed and enables simultaneous assessment of the pelvic region – thus diminishing the utility of computed tomography. The performance levels of MRI will probably continue to improve, with the use of dynamic MRI and MR spectroscopy. Despite the development of new markers like 11C and 18F choline and acetate, the sensitivity of positron emission tomography is still low. Prospective studies with an appropriate methodology are necessary for specifying the technique's value in this context.

Usefulness of Dynamic MR Imaging for the Evaluation of the Solitary Pulmonary Nodules Smaller than 15 mm: Differentiation between Benign and Malignant Nodules

Purpose: We wanted to evaluate the usefulness of dynamic magnetic resonance (MR) imaging for differentiating between benign and malignant solitary pulmonary nodules (SPNs). Materials and Methods: Sixteen patients who had an undetermined SPN (0.17, benign; 0.430.17). With 0.33 as the threshold of MER for distinguishing the malignant SPN group from the benign SPN group, the sensitivity, specificity, positive predictive value and negative predictive value were 100%, 70%, 50%, and 100%, respectively. The mean SLE for the benign SPN group was higher than that for the malignant SPN group (malignant; m= 0.0080.006/sec, benign; m=0.013 0.008/sec). With 0.025 as the threshold of the SLE, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 100%, 60%, 62.5%, 100% and 69.2%, respectively. Conclusion: Dynamic MRI was useful for differentiating between benign and malignant SPNs. Moreover, MER and SLE might be good indexes for distinguishing benign SPNs from malignant SPNs.

Dynamic gadolinium-enhanced magnetic resonance imaging of the wrist in patients with rheumatoid arthritis can discriminate active from inactive disease.

To determine the efficacy of dynamic gadolinium-enhanced magnetic resonance imaging (MRI) of the wrist in the evaluation of disease activity in patients with rheumatoid arthritis (RA). Thirty-six patients with RA (with different degrees of disease activity) and 5 healthy controls were studied. MRI was performed with a low-field (0.2T), extremity-dedicated machine. After an intravenous bolus injection of gadolinium-diethylenetriamine pentaacetic acid, 20 consecutive fast spin-echo images of 3 slices of the wrist were obtained every 18 seconds. The curves of synovial membrane enhancement identified the following 2 groups: controls and RA patients in remission, and RA patients with active or intermediately active disease. Both the rate of early enhancement (REE) and relative enhancement (RE) were significantly higher in patients with active RA than in those with inactive RA and controls. The REE and RE were significantly correlated with the number of swollen joints (P < 0.00001 and P = 0.003, respectively), the number of tender joints (P < 0.00001 and P = 0.004, respectively), the Ritchie index (P = 0.0002 for both REE and RE), the Disease Activity Score (P = 0.0004 and P = 0.0008, respectively), the Health Assessment Questionnaire (HAQ) (P = 0.0002 and P = 0.0007, respectively), early morning stiffness (P = 0.001 and P = 0.009, respectively), the C-reactive protein level (P = 0.015 and P = 0.03, respectively), the erythrocyte sedimentation rate (P = 0.03, RE only), and alpha2 globulins (P = 0.036 and P = 0.028, respectively). Our data support use of dynamic MRI for discriminating active from inactive RA. Enhancement curves are associated not only with laboratory and clinical indicators of inflammation, but also with the HAQ, a relevant predictor of RA functional outcome. This technique can be repeated frequently and is an excellent candidate for the ideal method for the followup of patients with RA.

Usefulness of Gd-DTPA contrast-enhanced dynamic MRI and serum determination of LDH and its isozymes in the differential diagnosis of leiomyosarcoma from degenerated leiomyoma of the uterus

This prospective study was conducted to identify the magnetic resonance imaging (MRI) characteristics of uterine leiomyosarcoma (LMS) and to evaluate the diagnostic accuracy of conventional MRI and dynamic MRI with or without serum measurement of lactate dehydrogenase (LDH) levels. Two hundred ninety-eight consecutive patients were entered in this study. In eligible 227 patients, ten patients with LMS and 130 patients with uterine degenerated leiomyoma (DLM) were included for the present study. Precontrast T1, T2 weighted images were obtained in all patients. Serum LDH and its isozymes were also measured. Dynamic MRI by Gd-DTPA was obtained in all patients with LMS and 32 patients with DLM in whom elevated LDH levels were observed. The contrast enhancement at 60 s after administration of Gd-DTPA was detected in all LMS, but absent in 28 of 32 DLM patients. Concerning serum LDH isozymes, both total LDH and LDH isozyme type 3 were elevated in all 10 patients with LMS. The sensitivity for determination of LMS with MRI alone, dynamic MRI alone, and combined use of MRI (including dynamic MRI) and serum LDH levels was 100% in each group. The specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 93.1%, 52.6%, 100%, and 93.1% with MRI alone, and 93.8%, 83.3%, 100%, and 95.2% with dynamic MRI alone, and 100%, 100%, 100%, 100% with combined use of LDH and MRI, respectively. In conclusion, the combined use of dynamic MRI and serum measurement of LDH (isozymes) seems to be useful in making a differentiated diagnosis of LMS from DLM before treatment.