T2-weighted Spin-echo MR Images Research Articles

One-Step Preparation of Highly Stable Copper-Zinc Ferrite Nanoparticles in Water Suitable for MRI Thermometry.

Superparamagnetic ferrite nanoparticles coated with a polymer layer are widely used for biomedical applications. The objective of this work is to design nanoparticles as a magnetic resonance imaging (MRI) temperature-sensitive contrast agent. Copper–zinc ferrite nanoparticles coated with a poly(ethylene glycol) (PEG) layer are synthesized using a one-step thermal decomposition method in a polymer matrix. The resulting nanoparticles are stable in water and biocompatible. Using Mössbauer spectroscopy and magnetometry, it was determined that the grown nanoparticles exhibit superparamagnetic properties. Embedding these particles into an agarose gel resulted in significant modification of water proton relaxation times T1, T2, and T2* determined by nuclear magnetic resonance measurements. The results of the spin-echo T2-weighted MR images of an aqueous phantom with embedded Cu0.08Zn0.54Fe2.38O4 nanoparticles in the presence of a strong temperature gradient show a strong correlation between the temperature and the image intensity. The presented results support the hypothesis that CuZn ferrite nanoparticles can be used as a contrast agent for MRI thermometry.

Standard Normal Fetal Lung Volume by MRI Measurement

Background: Pulmonary hypoplasia is a significant decrease in lung volume by any cause in comparison to the normal volume for gestational age. Objectives: To evaluate the application of prenatal magnetic resonance imaging in order to predict pulmonary hypoplasia, measurement of fetal lung volume (FLV) was aimed to establish a reference data in normal fetuses. Patients and Methods: Three hundred forty two fetuses with abnormal ultrasound findings underwent fast spin-echo T2-weighted MR imaging at a single tertiary care hospital (Shahid Faghihi Hospital, Shiraz, Iran). Data of 241 fetuses at 18 - 36 weeks’ gestation without thoracic malformations were obtained for a FLV normative curve. To acquire a best-fit formula for the mean total fetal lung volume based on each gestational week with 95% confidence interval (CI), we used the regression model applied by Rypens et al. This resulted in a formula calculating the expected fetal lung volume based on gestational age. A one-sample t-test was also carried out to compare the mean total fetal lung volume at each gestational week with the expected mean total fetal lung volume predicted by the formula by Rypens et al., Meyers et al., and Osada et al. Results: Normal FLV increased with gestational age as the spread of values. The expected fetal lung volume was derived from the following formula: Fetal lung volume (mL) = 0.002 × (gestational age [GA]2.913), in which GA is gestational weeks. FLV in our population had a more consistent correlation with Japanese fetuses than European or American fetuses. Conclusion: In fetuses with normal lungs, FLV distribution against gestational age is simply measured prenatally with MR imaging. A single universal formula might not be suitable for fetuses worldwide. In our region, acquired data were more consistent with Asian normal values.

Case 267.

History A 28-year-old man presented with lifelong anejaculation, which had become an issue because of family planning. The patient had a history of normal erections and experienced the sensation of orgasm without ever ejaculating. On physical examination, both testes were present in the scrotum, with normal dimensions and a normal epididymis bilaterally. The patient had a slightly tender left testicle, and digital rectal examination findings were normal. The patient underwent further investigation for the possibility of retrograde ejaculation with urine cytology, the results of which were negative. Genetic testing was performed to exclude Y chromosome microdeletions. Serum-luteinizing and follicle-stimulating hormone levels were normal, with a borderline low level of testosterone (7.6 nmol/L; normal range, 8.0-29.0 nmol/L). All other pertinent laboratory results were noncontributory. Pelvic MRI was requested to exclude an anatomic cause of anejaculation. MRI was performed in accordance with the standard clinical prostate protocol, with a dynamic contrast material-enhanced study ( Figs 1 - 3 ). CT of the upper abdomen was also performed ( Fig 4 ). The patient subsequently underwent cystoscopy, which revealed an intravesicular fluid-filled mass near the left ureteric orifice ( Fig 5 ). Figure 1a: (a) Coronal and (b, c) axial fast spin-echo T2-weighted MR images of the pelvis, with b being superior to c. Figure 1b: (a) Coronal and (b, c) axial fast spin-echo T2-weighted MR images of the pelvis, with b being superior to c. Figure 1c: (a) Coronal and (b, c) axial fast spin-echo T2-weighted MR images of the pelvis, with b being superior to c. Figure 2a: (a) Coronal T2-weighted (repetition time msec/echo time msec, 4574/86.5) MR image of the pelvis. (b) Axial T2-weighted (3000/85.4) MR image of the pelvis. Figure 2b: (a) Coronal T2-weighted (repetition time msec/echo time msec, 4574/86.5) MR image of the pelvis. (b) Axial T2-weighted (3000/85.4) MR image of the pelvis. Figure 3: Unenhanced axial fat-saturated T1-weighted (6.2/3.1) MR images. Figure 4: Coronal CT urogram. Figure 5: Image obtained at cystoscopy.

Optimization of ZD2 Peptide Targeted Gd(HP-DO3A) for Detection and Risk-Stratification of Prostate Cancer with MRI.

The aim of this work is to optimize a peptide targeted macrocyclic MRI contrast agent for detection and risk-stratification of aggressive prostate cancer. The optimized agent was prepared using click chemistry in the presence of CuSO4 and ascorbate at room temperature. The T1 and T2 relaxivities of ZD2-N3-Gd(HP-DO3A) are 5.44 and 7.10 mM-1 s-1 at 1.4 T, and 5.53 and 7.81 mM-1 s-1 at 7 T, respectively, higher than the previously reported ZD2-Gd(HP-DO3A). The specific tumor enhancement of the agent was investigated in male nude mice bearing aggressive PC3 human prostate cancer xenografts and slow-growing LNCaP tumor xenografts. Contrast enhanced MR images were acquired using a 2D spin-echo sequence and a 3D FLASH sequence with a 7 T small animal scanner. ZD2-N3-Gd(HP-DO3A) produced robust contrast enhancement in aggressive PC3 tumors and little enhancement in slow-growing LNCaP tumors. It produced 400% and 100% CNR increases in the T1-weighted 2D spin-echo MR images and 3D FLASH images of PC3 tumors, respectively, for at least 30 min at a dose of 0.1 mmol/kg. In contrast, less than 20% CNR increase was observed in the LNCaP tumors with both sequences. The optimized targeted contrast agent has higher relaxivities and are effective to detect aggressive PC3 tumors and differentiate the aggressive cancer from the slow-growing LNCaP prostate cancer in contrast enhanced MRI. ZD2-N3-Gd(HP-DO3A) has the promise for accurate detection and risk-stratification of aggressive prostate cancer.

3D Ultrashort TE MRI for Evaluation of Cartilaginous Endplate of Cervical Disk In Vivo: Feasibility and Correlation With Disk Degeneration in T2-Weighted Spin-Echo Sequence.

The purpose of this study was to evaluate the feasibility of 3D ultrashort TE (UTE) MRI in depicting the cartilaginous endplate (CEP) and its abnormalities and to investigate the association between CEP abnormalities and disk degeneration on T2-weighted spin-echo (SE) MR images in cervical disks in vivo. Eight healthy volunteers and 70 patients were examined using 3-T MRI with the 3D UTE cones trajectory technique (TR/TE, 16.1/0.032, 6.6). In the volunteer study, quantitative and qualitative assessments of CEP depiction were conducted for the 3D UTE and T2-weighted SE imaging. In the patient study, CEP abnormalities were analyzed. Intersequence agreement between the images obtained with the first-echo 3D UTE sequence and the images created by subtracting the second-echo from the first-echo 3D UTE sequence (subtracted 3D UTE) and the intraobserver and interobserver agreements for 3D UTE overall were also tested. The CEP abnormalities on the 3D UTE images correlated with the Miyazaki grading of the T2-weighted SE images. In the volunteer study, the CEP was well visualized on 3D UTE images but not on T2-weighted SE images (p < 0.001). In the patient study, for evaluation of CEP abnormalities, intersequence agreements were substantial to almost perfect, intraobserver agreements were substantial to almost perfect, and interobserver agreements were moderate to substantial (p < 0.001). All of the CEP abnormalities correlated with the Miyazaki grade with statistical significance (p < 0.001). Three-dimensional UTE MRI feasibly depicts the CEP and CEP abnormalities, which may be associated with the severity of disk degeneration on T2-weighted SE MRI.

Assessment of Arterial Wall Enhancement for Differentiation of Parent Artery Disease from Small Artery Disease: Comparison between Histogram Analysis and Visual Analysis on 3-Dimensional Contrast-Enhanced T1-Weighted Turbo Spin Echo MR Images at 3T

ObjectiveThe purpose of this study was to compare the histogram analysis and visual scores in 3T MRI assessment of middle cerebral arterial wall enhancement in patients with acute stroke, for the differentiation of parent artery disease (PAD) from small artery disease (SAD).Materials and MethodsAmong the 82 consecutive patients in a tertiary hospital for one year, 25 patients with acute infarcts in middle cerebral artery (MCA) territory were included in this study including 15 patients with PAD and 10 patients with SAD. Three-dimensional contrast-enhanced T1-weighted turbo spin echo MR images with black-blood preparation at 3T were analyzed both qualitatively and quantitatively. The degree of MCA stenosis, and visual and histogram assessments on MCA wall enhancement were evaluated. A statistical analysis was performed to compare diagnostic accuracy between qualitative and quantitative metrics.ResultsThe degree of stenosis, visual enhancement score, geometric mean (GM), and the 90th percentile (90P) value from the histogram analysis were significantly higher in PAD than in SAD (p = 0.006 for stenosis, < 0.001 for others). The receiver operating characteristic curve area of GM and 90P were 1 (95% confidence interval [CI], 0.86–1.00).ConclusionA histogram analysis of a relevant arterial wall enhancement allows differentiation between PAD and SAD in patients with acute stroke within the MCA territory.

T2 mapping of articular cartilage of the glenohumeral joint at 3.0T in healthy volunteers: a feasibility study.

The purpose of this study was to assess the T2 values of the glenohumeral joint cartilage in healthy asymptomatic individuals at 3.0T and to analyze the T2 profile of the humeral cartilage. This prospective study was approved by our institutional review board and written informed consent was obtained. Thirteen subjects (mean age, 28.6years; age range, 24-33 years) were included and underwent multiecho spin-echo T2-weighted MR imaging and T2 mapping was acquired. Regions of interest were placed on the humeral cartilage and glenoid cartilage on oblique coronal images. T2 profiles of humeral cartilage were measured from the bone-cartilage interface to the articular surface. Intra-observer agreement was analyzed using intraclass correlation coefficient (ICC). All 13 joints showed normal appearance on conventional T2-weighted images. The mean T2 values of humeral and glenoid cartilage were 50.5 ± 12.1 and 49.0 ± 9.9ms, respectively. Intra-observer agreement was good, as determined by ICC (0.736). Longer T2 values were observed at the articular surface with a tendency to decrease toward the bone-cartilage interface. The mean cartilage T2 value was 69.03 ± 21.2ms at the articular surface and 46.99 ± 19.6ms at the bone-cartilage interface. T2 values of the glenohumeral joint cartilage were similar to reported values of cartilage in the knee. The T2 profile of normal humeral cartilage showed a spatial variation with an increase in T2 values from the subchondral bone to the articular surface.

Localization and Segmentation of 3D Intervertebral Discs in MR Images by Data Driven Estimation.

This paper addresses the problem of fully-automatic localization and segmentation of 3D intervertebral discs (IVDs) from MR images. Our method contains two steps, where we first localize the center of each IVD, and then segment IVDs by classifying image pixels around each disc center as foreground (disc) or background. The disc localization is done by estimating the image displacements from a set of randomly sampled 3D image patches to the disc center. The image displacements are estimated by jointly optimizing the training and test displacement values in a data-driven way, where we take into consideration both the training data and the geometric constraint on the test image. After the disc centers are localized, we segment the discs by classifying image pixels around disc centers as background or foreground. The classification is done in a similar data-driven approach as we used for localization, but in this segmentation case we are aiming to estimate the foreground/background probability of each pixel instead of the image displacements. In addition, an extra neighborhood smooth constraint is introduced to enforce the local smoothness of the label field. Our method is validated on 3D T2-weighted turbo spin echo MR images of 35 patients from two different studies. Experiments show that compared to state of the art, our method achieves better or comparable results. Specifically, we achieve for localization a mean error of 1.6-2.0 mm, and for segmentation a mean Dice metric of 85%-88% and a mean surface distance of 1.3-1.4 mm.

Accuracy of Postcontrast 3D Turbo Spin-Echo MR Sequence for the Detection of Enhanced Inflammatory Lesions in Patients with Multiple Sclerosis

Therapeutic strategies for patients with MS partly rely on contrast-enhanced MR imaging. Our aim was to assess the diagnostic performance of 3D turbo spin-echo MR imaging with variable refocusing flip angles at 3T for the detection of enhanced inflammatory lesions in patients with multiple sclerosis. Fifty-six patients with MS were prospectively investigated by using postcontrast T1-weighted axial 2D spin-echo and 3D TSE MR images. The order in which both sequences were performed was randomized. Axial reformats from 3D T1 TSE were generated to match the 2D spin-echo images. The reference standard was defined by using clinical data and all MR images available. Three separate sets of MR images (2D spin-echo images, axial reformats, and multiplanar images from 3D TSE sequences) were examined in a blinded fashion by 2 neuroradiologists separately for the detection of enhanced MS lesions. Image artifacts and contrast were evaluated. No artifacts related to vascular pulsation were observed on 3D TSE images, whereas image artifacts were demonstrated on 2D spin-echo images in 41 patients. One hundred twelve enhanced MS lesions were identified in 19 patients. Sixty-four lesions were correctly diagnosed by using 2D spin-echo images; 90, by using 3D TSE axial reformatted views; and 106, by using multiplanar analysis of the 3D TSE sequence. Multiplanar analysis was 94.7% sensitive and 100% specific for the diagnosis of patients with at least 1 enhanced lesion. Contrast of enhanced MS lesions was significantly improved by using the 3D TSE sequence (P < .011). The 3D TSE sequence with multiplanar analysis is a useful tool for the detection of enhanced MS lesions.

1.5T versus 3T MRI for targeting subthalamic nucleus for deep brain stimulation

Background. Accurate stereotactic placement of the electrode into the subthalamic nucleus (STN) is imperative to the therapeutic efficacy of deep brain stimulation (DBS). However, it is not always possible to directly visualize the very small STN using 1.5T MR imaging. Objective. To evaluate whether 3T MR imaging can provide better identification of the STN and clinical outcome than 1.5T MR imaging. Methods. Thirty-nine patients with advanced Parkinson's disease underwent 1.5T (n = 16) or 3T (n = 23) fast spin echo T2-weighted (FSE-T2WI) MR imaging for targeting the STN. A semi-quantitative 3-point scoring system was proposed to rank the clearness of STN contour: Score “0” if non-visible; Score “1” if visible but with blurred margin; and “2” if visible with clear margin. The unified Parkinson's disease rating scale (UPDRS) was also compared before operation and post-operation. Results. The STN score was 2 in all the patients of the 3T group, whereas it was relatively blurred (mean score, 1.19) in the 1.5T group (P < 0.001). The number of microelectrode trajectories (1.2 versus 1.5; P < 0.05) was lower in the 3T group; consequently, the operative time was also less (P < 0.05) as compared with that in the 1.5T group. The outcome of UPDRS motor examination showed no significant difference in two groups. Conclusion. 3T MR imaging is a reliable and more accurate method for direct targeting of the STN for DBS surgery. However, the technique of high-sequence MR imaging may not influence the clinical outcome significantly.

Uterine cervical carcinoma: a comparison of two- and three-dimensional T2-weighted turbo spin-echo MR imaging at 3.0 T for image quality and local-regional staging

To compare three-dimensional (3D) T2-weighted turbo spin-echo (TSE) with multiplanar two-dimensional (2D) T2-weighted TSE for the evaluation of invasive cervical carcinoma. Seventy-five patients with cervical carcinoma underwent MRI of the pelvis at 3.0 T, using both 5-mm-thick multiplanar 2D (total acquisition time = 12 min 25 s) and 1-mm-thick coronal 3D T2-weighted TSE sequences (7 min 20 s). Quantitative analysis of signal-to-noise ratio (SNR) and qualitative analysis of image quality were performed. Local-regional staging was performed in 45 patients who underwent radical hysterectomy. The estimated SNR of cervical carcinoma and the relative tumour contrast were significantly higher on 3D imaging (P < 0.0001). Tumour conspicuity was better with the 3D sequence, but the sharpness of tumour margin was better with the 2D sequence. No significant difference in overall image quality was noted between the two sequences (P = 0.38). There were no significant differences in terms of the diagnostic accuracy, sensitivity, and specificity of parametrial invasion, vaginal invasion, and lymph node metastases. Multiplanar reconstruction 3D T2-weighted imaging is largely equivalent to 2D T2-weighted imaging for overall image quality and staging accuracy of cervical carcinoma with a shorter MR data acquisition, but has limitations with regard to the sharpness of the tumour margin.

Annular tears, fissures or HIZ?

Low back pain (LBP) is an acute or chronic pain in the lumbar or sacral regions [1], is highly prevalent and has substantial socioeconomic implications [2]. Jensen et al noted that low back pain is the second most common reason that patients seek medical care in the United States and that the estimated annual cost of related medical care is more than $8 billion [3]. Robertson noted also that the rate of low back–related disability has grown at a rate 14 times that of the population during the last 30 years [3]. MRI is established as the investigation of choice for assessing patients presenting with low back pain (LBP) and sciatica; recognised causes of nerve root compression include disc herniation and spinal stenosis, however many patients presenting with LBP and pain referred to the lower limb(s) show no evidence on imaging studies of nerve root compression, suggesting that there are other factors involved in the production of pain [4]. One of the prominent somatic sources of low back pain is the internal disc disruption of the lumbar spine, the socalled discogenic lumbar pain, which is the condition causing back pain without radiculopathy [5]. The annulus fibrosus is innervated by the recurrent meningeal nerve and by the small branches from the ventral ramus of the somatic spinal nerve; a proposed mechanism for such pain is inflammation of nerve roots (chemical radiculopathy) from leak of degenerative nuclear material through full-thickness annular tears [4, 5]. Compared with asymptomatic disks, painful disrupted lumbar intervertebral disks have higher concentrations of sensory fibers in their endplates and nucleus; this high concentration of sensory fibers, combined with increased levels of proinflammatory mediators such as IL-8 and PGE2, provides a substrate for hyperalgesia and presumably pain [6]. In this hyperalgesic state, even normal mechanical loading will be painful [6]. The concept of diskogenic pain caused by nocioceptive ingrowth into annular fissures has been supported only indirectly by observing a strong correlation between pain provocation and the presence of annular fissure during provocation diskography and subsequent CT imaging; annular fissures reaching the outer annular fibers are in fact the source of symptoms in patients suffering from chronic diskogenic LBP [6]. Discogenic lumbar pain is characterized by nonradicular pain, has a somatotropic rather than dermatomal pattern of pain projection; therefore, the use of symptoms and clinical findings to localize the level of abnormality is difficult; the source of discogenic pain is still unknown [7]. Ideally, a history and physical examination would consistently diagnose the source of a patient’s low back pain, and, if one diagnosed pain secondary to the intervertebral disc, one would be able to identify the exact level or levels involved; in reality, however, the exact source of low back pain is often illusive, because discogenic pain projects in a somatotropic rather than a dermatomal pattern, confirming and localizing a discogenic source, much less the exact level, using clinical findings alone remains unproven [8]. MR imaging provides an unique means to evaluate the morphologic status of intervertebral disks and their relationship to neural structures in patients with low back pain; moreover, the technique allows assessment of the biochemical status of the disk on T2-weighted spin-echo and fast spin-echo MR images [7]. One of the first structural abnormalities that predicted concordant pain provocation during disc stimulation was high-signal-intensity zones (HIZ) at first described by Aprill and Bogduk in 1992 [8]. HIZ are defined as small foci of high signal intensity at:

Preoperative detection of hepatic metastases: Comparison of diffusion-weighted, T2-weighted fast spin echo and gadolinium-enhanced MR imaging using surgical and histopathologic findings as standard of reference

Purpose The purpose of this study was to retrospectively compare the respective sensitivities of diffusion-weighted (DW), T2-weighted fast spin-echo (T2WFSE) and gadolinium chelate-enhanced MR imaging in the preoperative detection of hepatic metastases using intraoperative ultrasonographic and histopathologic findings as the standard of reference. Materials and methods Twenty-seven patients with 64 surgically and histopathologically proven hepatic metastases had MR imaging of the liver, including DW, T2WFSE and dynamic gadolinium chelate-enhanced MR imaging. Images from each MR sequence were separately analyzed by two readers with disagreements resolved by consensus readings. The findings on MR images were compared with intraoperative ultrasonographic and histopathologic findings on a lesion-by-lesion basis to determine the sensitivity of each MR sequence. Statistical review of the lesion-by-lesion analysis was performed with the McNemar test. Results DW, T2WFSE and gadolinium chelate-enhanced MR imaging allowed the depiction of 54/64 (84.4%; 95% CI: 73.1–92.2%), 44/64 (68.8%; 95% CI: 55.9–79.8%), and 51/64 (79.7%; 95% CI: 67.8–88.7%) hepatic metastases respectively. DW MR images allowed depiction of significantly more hepatic metastases than did T2WFSE and was equivalent to gadolinium chelate-enhanced MR imaging ( P = .002 and P = .375, respectively). Conclusion DW MR imaging is superior to T2WFSE imaging and equivalent to gadolinium chelate-enhanced MR imaging for the preoperative detection of hepatic metastases. Further studies however are needed to determine at what extent DW MR imaging can be used as an alternative to gadolinium chelate-enhanced MR imaging for the preoperative depiction of hepatic metastases.

MRI of the Pelvis in Women: 3D Versus 2D T2-Weighted Technique

The purpose of this study was to compare triplanar 2D T2-weighted turbo spin-echo MR images with reformatted images from a 3D T2-weighted turbo spin-echo sequence in analogous planes with respect to acquisition time, image quality, artifacts, and lesion detection. Forty-four consecutively enrolled women referred for pelvic MRI participated in the study. The protocol included 2D T2-weighted turbo spin-echo sequences in the axial, coronal, and sagittal planes and a single sagittal 3D T2-weighted turbo spin-echo sequence. The acquisition times of the 2D and 3D sequences were calculated. The sagittal 3D data sets were reformatted at 2-mm slice thickness in each plane and compared with the 2D data sets with respect to image quality, artifacts, and lesion detection. The mean acquisition time for the 3D sequence (419 seconds) was significantly shorter than acquisition time for the 2D sequences in three planes (728 seconds) (p < 0.0001). The readers favored the 3D reformats for cervical contrast (p = 0.005); otherwise, there was no significant difference between the 3D reformats and 2D data sets with regard to image quality and lesion detection. The 3D reformats were preferred with respect to respiratory (p < 0.001) and bowel (p < 0.001) motion. The 3D approach with multiplanar reconstructions is a promising tool for imaging the female pelvis because of time savings without compromise of image quality, the diagnostic information obtained, and the versatility of reconstructing images in any orientation.

Robust texture features for response monitoring of glioblastoma multiforme on T1-weighted and T2-FLAIR MR images: A preliminary investigation in terms of identification and segmentation

Image texture has recently attracted much attention in providing quantitative features that are unique to various different tissue types, in particular, in MR images of the brain. Such image features may be useful for tumor response quantification. As a first step, one needs to establish if these features are sensitive to different tissues of clinical relevance. Here, a novel method of texture analysis based on the Hartley transform has been investigated and applied to MR images of glioblastoma multiforme (GBM). Contrast-enhanced T1-weighted gradient-echo and T2-FLAIR spin-echo MR images of 27 GBM patients acquired prior to radiation therapy were available for analysis. Before computing texture features on these images, a novel image transformation was employed in the form of a power map computed from the localized Hartley transform of the image. Haralick statistical texture features were then computed based on the power map. This method was compared to the standard approach of obtaining texture features directly from the image. Twelve different features were computed on different resolution levels. On a regional resolution level, image texture features were identified that are able to correctly classify entire regions within T1-weighted and T2-FLAIR brain MR images of GBM patients into abnormal (containing contrast-enhancing GBM tumor) and brain tissue. Various metrics [area under the ROC curve (AUC), maximum accuracy, and Canberra distance] have been computed to quantify the usefulness of these features. On a local resolution level, it was investigated which of these features are able to provide a voxel-by-voxel enhancement that could be used for assisting the segmentation of the gross tumor volume on T1 images. The "gold standard" for this analysis was a gross tumor volume corresponding to the contrast-enhancing lesion visualized on T1-weighted images as segmented by a radiation oncologist. The Sum-mean and Variance features demonstrated the best performance overall. For the T1-weighted images, the identification performance of Sum-mean and Variance features computed from the power map was higher (AUC = 0.9959 and AUC = 0.9918, respectively) and with higher Canberra distances as compared to features computed directly from the images (AUC = 0.8930 and AUC = 0.9163, respectively). These results in T2-FLAIR images were even superior. The features computed from the power map showed an unequivocal identification (AUC = 1) with higher Canberra distances, whereas the performance of the features from the original images was slightly lower (AUC = 0.9739 and AUC = 0.9904, respectively). The same features computed on the power map of the T1-weighted images also provided superior enhancement in individual tumor voxels as compared to the features computed on the original images. The Sum-mean and Variance features are both useful for identifying and segmenting GBM tumors on localized Hartley transformed MR images.

Maturation of the Olfactory Bulbs: MR Imaging Findings

The detection of time-related maturational changes of the olfactory bulb (OB) on MR imaging may help early identification of patients with abnormal OB development and anatomic-based odor-cueing anomalies. Two separate reviewers retrospectively analyzed coronal T2-weighted spin-echo MR images of the frontobasal region in 121 patients. There were 22 patients who underwent MR imaging examinations several times, accounting for a total of 156 studies. Age range was 1 day to 19.6 years. OBs were bilaterally identified in all cases and categorized according to their shape and signal intensity. Three different anatomic patterns were identified. In pattern 1 (median age, 15 days; age range, 1-168 days), the OBs were round to oval with a continuous external T2-hypointense rim and a prominent T2-hyperintense central area. In pattern 2 (median age, 287 days; age range, 4 days-22 months), the OBs were U shaped, with thinning and concave deformation of the superior layer. A hyperintense central area on T2-weighted images was still visible. In pattern 3 (median age, 5.2 years; age range, 107 days-19.6 years), the OBs were small, round, or J shaped with a more prominent lateral part. No difference in signal intensity between the central area and the peripheral layer was identified anymore. The OBs show time-related maturational changes on MR imaging. There is a progressive reorganization of the peripheral neuronal layers and signal intensity changes of the central area, which are completed at the end of the second year, paralleling cerebral maturational changes.

Triceps brachii tendon: anatomic-MR imaging study in cadavers with histologic correlation

The purpose of this cadaveric study was to describe the normal MR anatomy of the triceps brachii tendon (TBT) insertion, to correlate the findings with those seen in anatomic sections and histopathologic analysis, and to review triceps tendon injuries. Twelve cadaveric elbows were used according to institution guidelines. T1-weighted spin-echo MR images were acquired in three planes. Findings on MR imaging were correlated with those derived from anatomic and histologic study. On MR images, the TBT had a bipartite appearance as it inserted on olecranon in all specimens. The insertion of the medial head was deeper than that of the long and lateral heads and was mainly muscular at its insertion, with a small amount of the tendon blending with the muscle distally, necessitating histologic analysis to determine if there was tendon blending with the muscle at the site of insertion and if the medial head inserted together with the common tendon or as a single unit. At histopathologic analysis, the three heads of the triceps tendon had a common insertion on the olecranon. The bipartite aspect of the tendon that was identified in the MR images was not seen by histologic study, indicating that there was a union of the medial and common tendons just before they inserted into bone. TBT has a bipartite appearance on MR images and inserts on olecranon as a single unit.

Medial Patellofemoral Ligament: Cadaveric Investigation of Anatomy with MRI, MR Arthrography, and Histologic Correlation

The purpose of this study was to use MRI with gross anatomic and histologic correlation in cadavers to define the anatomic details of the medial patellofemoral ligament. MRI of seven cadaveric knees was performed before and after intraarticular administration of a gadolinium solution. T1-weighted spin-echo MR images with and without fat suppression were acquired in three planes. Correlation was made between findings derived from MRI and cadaveric sections. Histologic analysis was performed on five specimens. The bilaminar and trilaminar appearance of the medial patellar ligamentous complex was defined on axial images. The medial patellofemoral ligament and the medial patellotibial ligament were best visualized on axial images. In three of five knees, the superficial fibers of the medial patellofemoral ligament were attached to the epicondyle in a position posterior to the attachment point of the tibial collateral ligament. In all three knees, the deep fibers of the medial patellofemoral ligament merged with and attached to the tibial collateral ligament. In two of these five knees, all fibers of the medial patellofemoral ligament were attached to the tibial collateral ligament. These findings were confirmed at histologic examination. The medial patellofemoral ligament can attach only to the tibial collateral ligament or to both the tibial collateral ligament and the femoral epicondyle. The bilaminar and trilaminar appearances of the medial patellar ligamentous complex and the course of the medial patellofemoral, medial patellomeniscal, and medial patellotibial ligaments were best defined on axial images.

Fast-recovery fast spin-echo T2-weighted MR imaging: a free-breathing alternative to fast spin-echo in the pediatric abdomen

In the mid 1990s, the fast spin-echo (FSE) and turbo spin-echo (TSE) T2-weighted (T2-W) sequences became available and are now widely accepted alternatives to conventional spin-echo sequences since they result in reduced acquisition times while maintaining tissue contrast. Since that time, there has been continued development of new sequences to further decrease acquisition times, minimize artifacts, and preserve lesion detection. The purpose of this pictorial essay is to qualitatively illustrate the newly available fast recovery (FR) FSE T2-W MR images of the abdomen compared with the images acquired using the routine FSE T2-W sequence in non-breath-hold studies in children.

Double-Contrast MRI for Accurate Staging of Hepatocellular Carcinoma in Patients with Cirrhosis

The aim of this study was to evaluate the accuracy of a double-contrast MRI protocol in staging of hepatocellular carcinoma (HCC) in patients with cirrhosis. This cross-sectional study was performed at a tertiary liver care center. Forty-eight patients with cirrhosis underwent double-contrast MRI for clinical care and liver transplantation. For each MRI examination, superparamagnetic iron oxide was infused, and 2D T2*-weighted spoiled gradient-recalled echo and T2-weighted echo-train spin-echo MR images were obtained for assessment of phagocytic function. Immediately afterward, a low-molecular-weight gadolinium compound was injected, and 3D T1-weighted spoiled gradient-recalled echo images were acquired dynamically for assessment of vascularity. Two blinded radiologists independently reviewed all MR images and assigned per-lesion and per-patient cancer confidence scores to determine the American Liver Tumor Study Group tumor stage. The imaging-based cancer scores and tumor stages were correlated with pathology reports. Performance parameters were computed for imaging-based measurements. Of the 48 study subjects, 25 had HCC (three, T1; 18, T2; one, T3; one, T4a; two, T4b). In total, there were 37 HCC nodules. The accuracy of MRI in prediction of pathologic tumor stage was 81-85% depending on the radiologist. Per-patient and per-lesion sensitivity in the diagnosis of HCC were 96% and 81% for one radiologist and 96% and 89% for the other. A double-contrast MRI protocol has high accuracy in staging of HCC in patients with cirrhosis.