T2-weighted MR Research Articles

The Effects of the Degenerative Changes in the Functional Spinal Unit on the Kinematics of the Cervical Spine

The sagittal kinematics of the cervical spine was evaluated using kinematic magnetic resonance imaging (kMRI). To investigate the effect of degenerative changes in the functional spinal unit on cervical kinematics by using kMRI. Few studies have, thus far, by using MR images, described the contribution of degenerative changes in the functional spinal unit to cervical kinematics; however, the exact cervical kinematics remains uncertain. A total of 289 consecutive symptomatic patients underwent dynamic cervical MRI in flexion, neutral, and extension postures. All digital measurements and calculations of the variations in segmental angular motion were automatically performed by an MR analyzer using true MR images with 77 predetermined points marked on each image. Each segment was assessed based on the extent of intervertebral disc degeneration (Grades 1-3) and cervical cord compression (groups A-C) observed on T2-weighted MR images. The segmental mobility of the segments with severe cord compression and moderate disc degeneration tended to be lower than that of the segments with severe cord compression and severe disc degeneration, and a significant difference was observed in the segmental mobility of the C5-C6 segment. Moreover, in all segments with moderate disc degeneration, the segmental mobility was significantly reduced in the presence of severe cord compression, as compared with no compression. However, in segments with severe disc degeneration, no significant differences were observed between the segmental mobility of the cord compression groups. Our results suggest that cervical cord compression may cause deterioration of cervical cord function and kinematic changes in the cervical spine. We hypothesize that the spinal cord may potentially protect its functions from dynamic mechanical cord compression by restricting segmental motion, and these mechanisms may be closely related to the intervertebral discs.

Static T2w MRU in Noncalcular Urinary Obstruction: Comparison of Its Two Techniques

The purpose of this study was to compare the diagnostic accuracy of T2-weighted (T2w) MR urography (MRU) techniques — the standard MRU using fast spin echo (FSE) and postprocessing maximum intensity projection (MIP) and the single-shot MRU — in the diagnosis of ureteric obstruction in patients with noncalcular urinary obstruction. The study included 150 patients admitted to our center between January 2005 and December 2006. There were 203 renal units with noncalcular obstruction; 53 patients had bilateral obstruction. Patients with calcular obstruction were excluded. There were 85 males and 65 females with a mean age of 50 (range: 5–83) years. All patients were examined with static MRU using both single-shot (thick slab) and multisection MRU. Using single-shot MRU, we obtained images at the direct coronal and oblique coronal, as well as sagittal, planes for each renal unit. Postprocessing MIP for the standard coronal heavy T2 source images to obtain coronal and oblique images was done. Among the obstructed 203 units, the intrinsic causes were present in 157 units (151 were stricture and six were ureteric tumors), while the extrinsic causes were present in 46 units (35 bladder tumor, four ureterocele, five retroperitoneal fibrosis, one prostatic tumor, and one local pelvic recurrence after radical cystectomy for bladder cancer). The overall accuracy of single-shot MRU was 89% and was 93% for the multisection MRU in cases of intrinsic ureteric obstruction, while in cases of extrinsic obstruction, it was 20% for single-shot MRU and 96% for multisection MRU. T2w static MRU is a very useful technique in diagnosing noncalcular ureteric obstruction. Multisection MRU has a high diagnostic accuracy and reliability over that of the single-shot technique. The single-section technique is very rapid and useful in diagnosing ureteric stricture so it could be used as a localizer, while multisection images with postprocessing MIP is mandatory, especially in cases of suspected ureteric tumors or extraureteric causes.

An approach for three-dimensional visualization using high-resolution MRI of the temporomandibular joint

To visualize the temporomandibular joint (TMJ) and the surrounding tissues in detail utilizing high-resolution MR images for the diagnosis of soft- and hard-tissue abnormalities. Clinically routine MR slices are processed by tissue segmentation and three-dimensional (3D) reconstruction and viewed with visualization software. A 1.5 T MRI system was used. The double-echo procedure for taking oblique sagittal images was applied to obtain both proton density-weighted (PDW) and T2 weighted (T2W) images simultaneously, with separate examinations in both open and closed mouth positions. Diagnosis of the abnormality in the placement and morphology of articular discs and the joint effusion status is usually performed using multiple MRI slices. Clinically routine continuous MR slices were processed by segmentation, reconstruction and visualization algorithms, and the mandibular condyle, fossa, articular disc and other intra-articular tissues were visualized on the 3D and two-dimensional (2D)-3D fusion images. In a clinical case, the anterior disc displacement without reduction, with mouth open and closed, was clearly depicted in the 3D images. Also 2D-3D superposed images with changeable tissue transparency successfully depicted the stereoscopic TMJ morphology in three dimensions. High-resolution PDW- and T2W MR images could be processed by tissue segmentation and 3D-reconstruction procedures, and the resultant images showed the anatomical details in an easily recognizable way. By the simultaneous visualization of both bony surfaces and soft tissues, disc displacement and deformity can be recognized in a 3D context. The additional superposition of the 3D visualization with the original 2D MR slices allows for a combination with conventional diagnostics.

Development of a Macromolecular Dual-Modality MR-Optical Imaging for Sentinel Lymph Node Mapping

To evaluate the effectiveness of a dual magnetic resonance-near infrared fluorescence optical imaging agent, poly(l-glutamic acid)-DTPA-Gd-NIR813, for both preoperative and intraoperative visualization and characterization of sentinel lymph nodes (SLN) in mice. Poly(L-glutamic acid) was conjugated with DTPA-Gd and NIR813 dye to obtain PG-DTPA-Gd-NIR813. To confirm drainage into the SLNs, this agent was injected subcutaneously into the front paw of nude mice followed by isosulfan blue (n = 6). Furthermore, PG-DTPA-Gd-NIR813 was injected subcutaneously at doses of 0.002 mmol Gd/kg (4.8 nmol eq. NIR813) and 0.02 mmol Gd/kg (48 nmol eq. NIR813) (n = 3/dose). To differentiate metastatic from nonmetastatic lymph nodes, nude mice bearing human oral squamous cell carcinoma (DM14) were injected intralingually with 0.02 mmol Gd/kg PG-DTPA-Gd-NIR813 (n = 3). Pre- and postcontrast images were taken using 4.7 T Bruker MRI scanner and Xenogen optical imaging system. The status of lymph nodes resected under the guidance of optical imaging was confirmed by histologic examinations. PG-DTPA-Gd-NIR813 colocalized with isosulfan blue, indicating drainage to the SLN. After subcutaneous injection, axiliary and branchial lymph nodes were clearly visualized with both T1-weighted MR and optical imaging within 3 minutes of contrast injection, even at the lowest dose tested (0.002 mmol Gd/kg). After intralingual injection in tumor-bearing mice, MR imaging identified 4 of the 6 superficial cervical lymph nodes, whereas near-infrared fluorescence (NIRF) optical imaging identified all 6 cervical nodes. The pattern of contrast enhancement of SLN visualized in MR images showed a characteristic ring-shaped appearance with a central filling defect, possibly resulting from nodal infiltration of metastatic lesions. Histopathologic examination of the SLNs resected under NIRF imaging guidance revealed micrometastases in all 6 SLNs identified by NIRF imaging. The dual modality imaging method demonstrated in this study represents an effective technique for localization and characterization of SLN.

The warburg effect and tumour cell survival in human GBMs

Introduction: GBMs are resistant to apoptosis induced by the hypoxic microenvironment and standard therapies including radiation and chemotherapy. We postulate that the Warburg effect, a preferential glycolytic phenotype of tumor cells even under aerobic conditions, plays a role in these aberrant pro-survival signals. In this study we quantitatively examined the expression profile of hypoxia-related glycolytic genes within pathologically- and MRI-defined “centre” and “periphery” of GBMs. We hypothesize that expression of hypoxia-induced glycolytic genes, particularly hexokinase 2 (HK2), favours cell survival and modulates resistance to tumour cell apoptosis by inhibiting the intrinsic mitochondrial apoptotic pathway.
 Methods: GBM patients underwent conventional T1-weighted contrast-enhanced MRI and MR spectroscopy studies on a 3.0T GE scanner, prior to stereotactic sampling (formalin and frozen) from regions which were T1-Gad enhancing (“centre”) and T2-positive, T1-Gad negative (“periphery”). Real-time qRT-PCR was performed to quantify regional gene expression of glycolytic genes including HK2. In vitro functional studies were performed in U87 and U373 GBM cell lines grown in normoxic (21% pO2) and hypoxic (< 1%pO2) conditions, transfected with HK2 siRNA followed by measurement of cell proliferation (BrdU), apoptosis (activated caspase 3/7, TUNEL, cytochrome c release) and viability (MTS assay). 
 Results: There exists a differential expression profile of glycolytic enzymes between the hypoxic center and relatively normoxic periphery of GBMs. Under hypoxic conditions, there is increased expression of HK2 at the mitochondrial membrane in GBM cells. In vitro HK2 knockdown led to decreased cell survival and increased apoptosis via the intrinsic mitochondrial pathway, as seen by increased mitochondrial release of cytochrome-C.
 Conclusions: Increased expression of HK2 in the centre of GBMs promotes cell survival and confers resistance to apoptosis, as confirmed by in vitro studies. In vivo intracranial xenograft studies with injection of HK2-shRNA are currently being performed. HK2 and possibly other glycolytic enzymes may provide a target for enhanced therapeutic responsiveness thereby improving prognosis of patients with GBMs.

MRI at 3 Tesla detects no evidence for ischemic brain damage in intensively treated patients with homozygous familial hypercholesterolemia

Homozygous familial hypercholesterolemia (FH) is considered a model disease for excessive plasma cholesterol levels. Patients with untreated homozygous FH have a markedly increased risk for premature atherosclerosis. The frequency and extent of ischemic brain damage detectable by high-field magnetic resonance imaging (MRI) after long-term intensive treatment are unknown. In a case control study, five patients with homozygous FH (one male and four females; mean age: 23.6 +/- 9.2, range: 12-36 years; mean pre-treatment serum total cholesterol level: 26.9 +/- 3.24 mmol/L; all patients with documented atherosclerotic plaques in the carotid arteries) and five age- and sex-matched healthy controls were studied. All patients had been on maximal lipid-lowering medication since early childhood, and four of them were also on treatment with low-density lipoprotein (LDL) apheresis at bi-weekly intervals. Brain MRI was performed at 3 Tesla field strength with fluid-attenuated T2-weighted inversion recovery and T1-weighted spin-echo MR pulse sequences and subsequently evaluated by two independent readers. The maximal lipid-lowering treatment reduced the total serum cholesterol by more than 50% in the patients, but their serum concentrations were still 3.6-fold higher than those found in the controls (11.9 +/- 4.2 vs. 4.5 +/- 0.5 mmol/L; p < 0.0047). No brain abnormality was observed in any of the patients with homozygous FH. Homozygous FH patients on intensive cholesterol-lowering therapy have no evidence of ischemic brain damage at 3 Tesla MRI despite the remaining high cholesterol levels.

Relación entre el volumen lesional cerebral total en resonancia magnética secuencia T2 y el daño neuroaxonal en la sustancia blanca aparentemente normal del tronco del encéfalo en la esclerosis múltiple remitente-recurrente

To evaluate the relationship between the total brain T2-hyperintense lesion volume (TBT2LV) and the axonal damage in the normal-appearing white matter of brainstem measured by 1H-MRS in a group of early relapsing-remitting multiple sclerosis patients. 40 relapsing-remitting multiple sclerosis patients and ten sex- and age-matched healthy subjects were prospectively studied for two years. T2-weighted MR and 1H-MRS imaging were acquired at time of recruitment and at year two. The TBT2LV was calculated with a semiautomatic program; N-acetylaspartate (NAA), creatine (Cr) and choline (Cho) resonances areas were integrated with jMRUI program and the ratios were calculated for four volume elements that represented the brainstem. At basal study we obtained an axonal loss (as a decrement of NAA/ Cho ratio) in the group of patients compared with controls (p = 0.017); this axonal loss increased at the second year of the follow-up for patients (NAA/Cho decrease, p = 0.004, and NAA/Cr decrease, p = 0.002) meanwhile control subjects had no significant metabolic changes. Higher lesion load was correlated with a poor clinical outcome, being the correlation between the basal TBT2LV and the Expanded Disability Status Scale at second year (r = 0.299; p = 0.05). Besides, axonal loss was not homogeneous for all multiple sclerosis patients, being stronger in the subgroup of patients with high basal TBT2LV (p = 0.043; ANOVA). Our data suggest that axonal damage is early in multiple sclerosis and higher in patients high basal TBT2LV, suggesting a possible relationship between these two phenomena.

MRI Determination of Conus Medullaris Level in an Adult Population in Turkey

The level of the conus medullaris (CM) in adults has been described in many studies with cadavers and living people. T1-weighted sagittal spin-echo MR images of the lumbar spine were reviewed in 364 consecutive patients (207 women, 157 men) with a mean age of 45 years (range 18-80). The most common level of CM was the L1-L2 intervertebral disc level in females and the T12-L1 intervertebral disc level in males. The distribution of CM location in a large adult population was shown to range from the T11-T12 intervertebral disc level to L2-L3 intervertebral disc level.

3D Medical images registration

Abstract Image registration is the process of overlaying images of the same scene. As we search for the best alignment of the two images by transforming one into the other, it is a very crucial issue to assess how similar two images actually are. The next step in computer aided diagnosis is called “assessment of the similarity”. There are two main classes of similarity measures namely feature-based and intensity-based. In this paper two similarity measures: NCC-normalized cross correlation and GD-gradient difference are mentioned. Normalized Cross Correlation has been used for various registration problems, because difference in contrast and brightness should not affect the similarity measure. Goal the current study is to align T1-weighted and T2-weighted MR knee slices. Both sequences are converted to a fuzzy representation. Then, the entropy and energy measures are employed in the NCC and GD methods. The alignment based on energy and entropy fuzzy mcasures shows a significant improvement in comparision with thc implementation of the original image.

MR Imaging in Patients With Crohn Disease: Value of T2- Versus T1-weighted Gadolinium-enhanced MR Sequences With Use of an Oral Superparamagnetic Contrast Agent

MR Imaging in Patients With Crohn Disease: Value of T2- Versus T1-weighted Gadolinium-enhanced MR Sequences With Use of an Oral Superparamagnetic Contrast Agent

Usefulness of [18F]FDG-PET kinetic analysis in non-enhancing primary central nervous system lymphoma: Case report

A 62-year-old woman experienced headache and rapidly progressive left hemiparesis over 2 weeks. Diffusion-weighted and fluid-attenuated inversion recovery MR images of the head showed increased signal intensity in the right basal ganglia, periventricular white matter and the brain stem. Enhancement was not observed on a T1-weighted spin-echo MR image after the administration of a contrast material. An 18F-fluorodeoxyglucose positron emission tomography ([18F]FDG-PET) study with kinetic analysis showed decreased FDG transport and increased hexokinase activity in the lesions compared with the contralateral hemisphere. The diagnosis was made by biopsy of the right caudate head and pathologic specimens were positive for malignant large-cell lymphoma, B-cell phenotype. The patient received high-dose methotrexate with CHOP chemotherapy, and an [18F]FDG-PET study with kinetic analysis showed decreased hexokinase activity after the first chemotherapy. Kinetic [18F]FDG-PET analysis may be useful to diagnose and monitor the treatment effect in non-enhancing primary central nervous system lymphoma.

Automated 3D Surface Display for Evaluating Meniscal Tears Aided by Fuzzy Expert System

This paper proposes an automated procedure for segmenting menisci in MR images of a human knee aided by fuzzy expert system. A three-dimensional (3D) MR volumetric images composed of many slice images consists of several parts: bone marrow, meniscus, periarticular liquor, cartilage and others. We employ both T1-weighted and T2-weighted MR images to identify the menisci with high accuracy. After a registration between these images is manually done on a computer display, our procedure aided by fuzzy expert system can automatically segment meniscal regions from 3D MR images. Physicians can observe the 3D shapes of meniscal tears from any point of view on the display. We examined five subjects including a normal knee and three injured knees. The all meniscal regions were significantly identified, and these 3D shapes were displayed. The patterns of meniscal tears were identified on the display for all subjects. In a subject, since the preoperative and postoperative 3D meniscal shapes were clearly viewed, we easily recognized the operated meniscal regions. Thus, the system can provide useful information for diagnosing meniscal tears.

Potential for Misinterpretation of Combined T1- and T2-weighted Contrast-enhanced MR Imaging of Cartilage

Potential for Misinterpretation of Combined T1- and T2-weighted Contrast-enhanced MR Imaging of Cartilage

Jugular foramen syndrome caused by choleastatoma

Unilateral paresis of 9th–11th cranial nerves together is defined as jugular foramen (Vernet's) syndrome. A cholesteatoma case that penetrated into intracranial area after eroding temporal bone and led to jugular foramen syndrome is presented here, since such a case has not been reported in the literature hitherto. A 46-year-old male patient was evaluated for hoarseness. It was learnt from his anamnesis that he had been operated for otitis media nearly 20 years ago. Uvula deviated towards right. Loss of gag reflex was remarkable on the left. Paresis was found on the left vocal cord. There was weakness in rotation of the head to the right. Computerized tomography (CT) scan revealed that the temporal bone lost its integrity and that there was an extra-axial hypodense mass neighboring pontocerebellum. Post-contrast magnetic resonance imaging showed that the mass, which showed thin, regular circular contrasting and which was hypointense in T1-weighted MR and hyperintense in T2-weighted MR, extended to the left jugular foramen. The mass was totally removed with left sub-occipital approach in the treatment. After the treatment, hoarseness, weakness in the rotation movement of the head and loss of gag reflex recovered totally, while deviation in the uvula was permanent. Cholesteatomas can extend to posterior fossa and cause jugular foramen syndrome. Early surgery is important to completely reverse the lost nerve functions in treatment.

Quantitative measurement of regional signal intensity changes of high grade gliomas following radiotherapy using T1-weighted contrast enhanced MRI imaging

Quantitative measurement of regional signal intensity changes of high grade gliomas following radiotherapy using T1-weighted contrast enhanced MRI imaging

Quantitative measurement of regional signal intensity changes of high grade gliomas following radiotherapy using T1-weighted contrast enhanced MRI imaging

Identifying early predictors of treatment response is highly desirable for patients with high grade gliomas, as it might permit the selection of more intensive therapies for the appropriate patient population. The purpose of this study was to test our hypothesis that changes in regional tumor microvasculature, measured from T1-weighted MR and Gd-DPTA uptake signal intensity (SI) changes following radiotherapy may predict the outcome in patients with high grade gliomas.

Fogging on T2-weighted MR after acute ischaemic stroke: how often might this occur and what are the implications?

"Fogging" is the temporary loss of visibility of an infarct on CT which occurs in the subacute phase at about 2 weeks after stroke. It occurs in up to 40% of medium to large infarcts on CT. It is unclear whether or how often fogging occurs on T2-weighted MR, but if it does occur, it can cause underestimation of true infarct size. This study examined the possible frequency and time scale of "fogging" on T2-weighted MR. We conducted a blinded, independent review of prospectively collected MR scans from patients with symptoms of cortical ischaemic stroke, scanned sequentially up to 7 weeks after stroke. On each scan maximum infarct area was measured, and the infarct extent and swelling were coded on a validated scale. "Fogging" was suggested by reduced infarct extent between initial and subsequent scans. In 30 patients (with 74 scans) there was some apparent "fogging" in 50% of patients between 6 and 36 days (median 10 days) after stroke. Reduction in infarct extent on T2-weighted MR which may be attributed to "fogging" occurs in a significant proportion of patients with cortical infarcts. This may lead to an underestimation of true final infarct extent. This suggests that true infarct extent on T2-weighted MR can probably only be assessed on scans obtained beyond 7 weeks after stroke.

Time-of-Flight MR Angiography of Dyke-Davidoff-Masson Syndrome: Clinical and Radiological Correlations

The objective of the present study was to determine the presence and level of occlusion in the cerebral arteries using three-dimensional time-of-flight (TOF) MR angiography. Routine axial T1-weighted, axial or coronal T2-weighted MR imaging, proton MR spectroscopy, diffusion-weighted MR imaging and TOF MR angiography of the brain were performed in nine patients with DDMS (five congenital and four acquired). Of congenital cases, three with an occlusion at the root of the MCA (cases 3,4,5) and one with an occlusion on M1, M2 and M3 (case 7) had severe clinical findings, and one with an occlusion on M2 and M3 (case 8) had moderate clinical findings. Cerebral encephalomalacia was found in four congenital DDMS cases (cases 3,4,7,8). Of four acquired DDMS cases; one with an occlusion on M1, M2 and M3 (case 1), and one with an occlusion on M2 and M3 (case 6) had moderate clinical findings, and one with an occlusion on M2 (case 2) and one with an occlusion on M3 (case 9) had mild clinical findings. Contrary to the congenital DDMS cases (4/5), only one of acquired cases (1/4) had encephalomalacia. Our results suggest that unilateral cerebral arterial occlusion is the main factor which results in DDMS, and the level of occlusion has a significant effect on the severity of clinical findings. TOF MR angiography, which is a non-invasive technique, provides prognostic information by showing the occluded arteries and the level of occlusion.

Distribution of intramyocardially injected extracellular MR contrast medium: effects of concentration and volume.

The purpose of this study was to assess the potential of intramyocardially injected Gd-DTPA solution as a marker for distribution of intramyocardially delivered therapeutic solutions. The effects of concentration and volume of the extracellular MR contrast medium Gd-DTPA on signal intensity and spatial extent of enhancement was determined after intramyocardial delivery. In anesthetized pigs (n=11), mixtures of Gd-DTPA (0.15, 0.1 and 0.05 mmol/ml) and Evan's blue tissue dye (3%) were injected into the wall of the left ventricle. In each pig 1 ml of 0.15 mmol/ml, 2 ml of 0.1 ml and 3 ml of 0.05 mmol/ml Gd-DTPA were injected remote from each other. Arterial blood pressure, heart rate and ECG were monitored throughout the procedure. Five minutes after injections were performed, the pigs were killed and the hearts excised. T1-weighted spin-echo MR images were acquired to measure regional signal intensity (SI) and extent of the enhanced regions. The hearts were sliced and mass of blue stained regions was determined and compared with mass of enhanced areas on MRI. Gd-DTPA significantly (p<0.001) increased regional SI compared with remote myocardium in a concentration dependent fashion (109 +/- 4% at 0.05 mmol/ml, 202 +/- 7% at 0.1, and 327 +/- 6% at 0.15) while the mass of enhanced region was 0.6 +/- 0.1 g after injection of 1 ml, 1.4 +/- 0.2 g after 2 ml and 2.3 +/- 0.3 g after 3 ml (p<0.001). Regression and Bland-Altman analysis revealed that there was close correlation and agreement between MRI and histomorphometry (r=0.98, p<0.001). Magnitude and spatial extent of enhancement depend on concentration and volume of injected contrast medium. Intramyocardial injection of extracellular MR contrast media may be useful as a marker for the extent of distribution of intramyocardially delivered therapeutic solutions.

SCLEROSING STROMAL TUMOR OF THE OVARY: A CASE REPORT

Sclerozing stromal tumor of the ovary is an extremely rare neoplasm occurring predominantly in the second and third decades of life. Most patients have menstrual irregularities and pelvic pain. Infertility and endometrial pathology have also been described. A 34-year-old woman presented with hirsutism and oligomenorrhea of three months duration. Ultrasound examination showed a heterogeneous right ovarian tumor consisting of predominantly solid tissue with several loculated cysts. On T2-weighted pelvic MR images, signal intensities of the cystic components were high and those of the solid components were heterogeneous, ranging from intermediate-high to high. Dynamic MRI marked early enhancement of solid components in the right ovary. The specimen obtained from endometrial curettage showed proliferative endometrium. Preoperative serum levels of tumor markers were in normal range: preoperative serum levels of testosterone (T) (2.42 ng/ml; normal for adult females 0.1-0.8 ng/ml) and dehydroepiandrosterone-sulphate (DHEA-S) (232.4 microg/dL; normal for adult female, 35-430 microg/dL) were measured and the T value was found increased. At laparotomy, a left ovarian mass was found attached to the right infundibulopelvic ligament and a left oophorectomy was performed. The mass was described as benign by frozen analysis. Definitive histopathological diagnosis was sclerozing stromal tumor of the ovary (SST). The histologic features included a pseudolobular pattern with focal areas of sclerosis and a two-cell population of spindled and polygonal cells. Immunohistochemical studies showed positive smooth muscle actin and negative cytokeratin, keratin, S100 and desmin. The T value decreased postoperatively (0.57 ng/ml).