T2-weighted Fast Spin-echo Technique Research Articles

Forensic age estimation via 3-T magnetic resonance imaging of ossification of the proximal tibial and distal femoral epiphyses: Use of a T2-weighted fast spin-echo technique

Radiation exposure during forensic age estimation is associated with ethical implications. It is important to prevent repetitive radiation exposure when conducting advanced ultrasonography (USG) and magnetic resonance imaging (MRI). The purpose of this study was to investigate the utility of 3.0-T MRI in determining the degree of ossification of the distal femoral and proximal tibial epiphyses in a group of Turkish population. We retrospectively evaluated coronal T2-weighted and turbo spin-echo sequences taken upon MRI of 503 patients (305 males, 198 females; age 10–30 years) using a five-stage method. Intra- and interobserver variations were very low. (Intraobserver reliability was κ=0.919 for the distal femoral epiphysis and κ=0.961 for the proximal tibial epiphysis, and interobserver reliability was κ=0.836 for the distal femoral epiphysis and κ=0.885 for the proximal tibial epiphysis.)Spearman's rank correlation analysis indicated a significant positive relationship between age and the extent of ossification of the distal femoral and proximal tibial epiphyses (p<0.001). Comparison of male and female data revealed significant between-gender differences in the ages at first attainment of stages 2, 3, and 4 ossifications of the distal femoral epiphysis and stage 1 and 4 ossifications of the proximal tibial epiphysis (p<0.05). The earliest ages at which ossification of stages 3, 4, and 5 was evident in the distal femoral epiphysis were 14, 17, and 22 years in males and 13, 16, and 21 years in females, respectively. Proximal tibial epiphysis of stages 3, 4, and 5 ossification was first noted at ages 14, 17, and 18 years in males and 13, 15, and 16 years in females, respectively.MRI of the distal femoral and proximal tibial epiphyses is an alternative, noninvasive, and reliable technique to estimate age.

Diagnostic performance of T2-weighted CMR for evaluation of acute myocardial injury

Summary We compared the performances of two different fat suppression T2-weighted fast spin echo sequences and demonstrated that T2-weighted CMR has high specificity but overall low sensitivity for detection of myocardial injury. More robust CMR techniques are needed for the detection of acute myocardial injury. Background Edema-sensitive T2-weighted cardiac magnetic resonance (CMR) based on fast spin-echo (FSE) imaging is a useful modality to detect acute myocardial injury. Conventional T2-weighted CMR uses three inversion-recovery (IR) pulses, the first two to null the blood signal, and the last one (STIR) to null fat signal, but suffers from reduced myocardial signal and signal dropout. We compared the performances of two different fat suppression T2-weighted FSE sequences: a) STIR (FSE-STIR) and b) spectral adiabatic inversion recovery fat suppression (FSE-SPAIR) for detection of myocardial injury in patients with cardiomyopathy. Methods 65 consecutive patients referred for CMR evaluation of myocardial structure and function underwent FSE-STIR and FSE-SPAIR in addition to cine and late gadolinium enhancement CMR as part of the routine clinical protocol. T2-weighted FSE images were independently evaluated by two readers, blinded to the clinical history and type of sequence, for image quality and artifacts (Likert scale 1-5), and presence of increased myocardial T2 signal suggestive of edema. Disagreements in interpretation of myocardial edema were resolved by consensus. In addition, presence of increased T2 signal suggestive of myocardial edema based on the clinical CMR interpretation, incorporating all CMR sequences available in the study, was also recorded for comparison. Troponin levels acquired during the time of the referral were recorded, and patients with recent (<30 days) troponin elevation greater than 2 times upper limit of normal were diagnosed with acute myocardial injury. The diagnostic performance of each T2-weighted FSE technique for detection of myocardial injury was evaluated. Results There were 22/65 patients (34%) with evidence of acute myocardial injury. Image quality and artifact scores were significantly better with the FSE-SPAIR technique compared to FSE-STIR (2.15 vs 2.68, p<0.01; 2.62 vs 3.05, p<0.01, respectively). The sensitivity, specificity, positive predictive value and negative predictive value are as follows: 27%, 93%, 67%, 71% for FSE-SPAIR, 36%, 91%, 67%, 74% for FSE-STIR and 68%, 98%, 94%, 84% for clinical interpretations. There was a statistically significant difference in sensitivity between the clinical interpretation and each of the T2-weighted techniques, but not between the independent T2-weighted techniques. Conclusions

Comparison of image quality in magnetic resonance imaging of the knee at 1.5 and 3.0 Tesla using 32-channel receiver coils

We examined to what degree the visualization of anatomic structures in the human knee is improved using 3.0-T magnetic resonance imaging (MRI) and many element RF receive coils as compared to 1.5 T. We imaged 20 knees at 1.5 and 3.0 T using T2-weighted STIR, T2-weighted gradient echo, T1-weighted spin-echo, true-FISP and T2-weighted fast spin echo techniques in conjunction with 32-element RF coil arrays. The 3.0-T examination was considerably faster than its 1.5-T counterpart. A superior subjective visibility at 3.0 T vs 1.5 T was found in 27 of 50 evaluated structures (meniscus, ligaments) with the exception of true-FISP techniques. The 3.0-T examination provided a better visibility (evaluated by blinded consensus-reading by two radiologists) of small structures such as the ligamentum transversum genu. Also, cartilage was better delineated at 3.0 T. A 23% increased average signal-to-noise ratio as assessed using a temporal filter was observed at 3.0 T as compared to 1.5 T. At 3.0 T, imaging of the human knee is faster and results in a subjective visibility of anatomic structures that is superior to and competitive with 1.5 T.

Implantation of deep brain stimulators into the subthalamic nucleus: technical approach and magnetic resonance imaging-verified lead locations.

Chronic deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a procedure that is rapidly gaining acceptance for the treatment of symptoms in patients with Parkinson disease (PD), but there are few detailed descriptions of the surgical procedure itself. The authors present the technical approach used to implant 76 stimulators into the STNs of patients with PD and the lead locations, which were verified on postoperative magnetic resonance (MR) images. Implantation procedures were performed with the aid of stereotactic MR imaging, microelectrode recording (MER) in the region of the stereotactic target to define the motor area of the STN, and intraoperative test stimulation to assess the thresholds for stimulation-induced adverse effects. All patients underwent postoperative MR imaging, which was performed using volumetric gradient-echo and T2-weighted fast-spin echo techniques, computational reformatting of the MR image into standard anatomical planes, and quantitative measurements of lead location with respect to the midcommissural point and the red nucleus. Lead locations were statistically correlated with physiological data obtained during MER and intraoperative test stimulation. The authors' approach to implantation of DBS leads into the STN was associated with consistent lead placement in the dorsolateral STN, a low rate of morbidity, efficient use of operating room time, and robust improvement in motor function. The mean coordinates of the middle of the electrode array, measured on postoperative MR images, were 11.6 mm lateral, 2.9 mm posterior, and 4.7 mm inferior to the midcommissural point, and 6.5 mm lateral and 3.5 mm anterior to the center of the red nucleus. Voltage thresholds for several types of stimulation-induced adverse effects were predictive of lead location. Technical nuances of the surgery are described in detail.

Endoscopic Third Ventriculocisternostomy: MR Assessment of Patency with 2-D Cine Phase-Contrast versus T2-Weighted Fast Spin Echo Technique

Purpose: To determine if fast spin-echo T2 (FSE) is of equal value to flow-sensitive 2D cine phase-contrast (CPC) to assess patency of endoscopic third ventriculocisternostomies (VC). Patients and Methods: We reviewed clinical charts and MR scans of 27 patients who underwent third VC for treatment of obstructive hydrocephalus. Thirty-nine postoperative scans included both sequences and were assessed for the presence or absence of flow-related signal changes. Results: In 28 cases, FSE, CPC, and clinical findings suggested patency. In 1 case, CPC and FSE suggested occlusion, which was confirmed clinically and operatively. In the remaining cases, FSE showed better clinical correlation than did CPC. Conclusion: The assessment of third VC patency with FSE, a sequence available on most clinical scanners without a requirement for special hardware and software, is at least as sensitive in the qualitative assessment of VC function as CPC.

MR evaluation of rotator cuff pathology using T2-weighted fast spin-echo technique with and without fat suppression.

This study was designed to compare MR imaging findings from T2-weighted fast spin-echo images with and without fat suppression and then to compare surgical results with those MR imaging interpretations in the evaluation of rotator cuff disease. T2-weighted fast spin-echo images--with and without fat suppression--of 177 shoulder MR imaging studies were reviewed separately in a retrospective, randomized, and blinded fashion. Both sets of images were read in conjunction with the corresponding proton density-weighted images. The diagnosis of normal tendon, tendinosis, degeneration, and partial- and full-thickness tears was made using established criteria. T2-weighted fast spin-echo techniques with and without fat suppression showed excellent agreement in the diagnosis of normal tendon (kappa=.90) amd full-thickness tears (kappa=.98), good agreement for partial tears (kappa=.70) and moderate agreement for the combined group of tendinosis and degeneration (kappa=.53). MR imaging and surgical correlation in 43 patients showed 86% specificity (95% confidence interval, 65-96%) for intact tendons, and 100% sensitivity (95% confidence interval, 82-100%) for full-thickness tears on T2-weighted fast spin-echo imaging--both without and with fat suppression. For partial tears, MR imaging showed a sensitivity of 92% (95% confidence interval, 65-99%) with fat suppression and 67% (95% confidence interval, 39-86%) without fat suppression. T2-weighted fast spin-echo imaging--with or without fat suppression--is a highly sensitive technique in the diagnosis of normal tendons and complete tears of the rotator cuff. Because of increased lesion conspicuity, fat suppression tends to perform better in the diagnosis of partial tears.

Silicone breast implants in vivo: MR imaging.

This study was designed to evaluate pulse sequences and patient positioning for MR imaging of silicone breast implants in patients. One hundred forty-three patients (281 silicone implants) underwent imaging over a 21-month period. The combination of a T2-weighted fast spin echo technique (SE), T2-weighted fast SE with water suppression, and T1-weighted SE with fat suppression is recommended to reliably differentiate silicone from other breast tissues and to identify intracapsular and extracapsular ruptures or leaks. Seventy of the 143 patients underwent removal of their silicone implants. The sensitivity for detection of silicone implant rupture was 76%, with a specificity of 97%. Positioning the patient prone improved image quality.