T2-weighted Spin-echo Magnetic Resonance Imaging Research Articles

Benign and malignant gynecologic disease: clinical importance of fluid and peritoneal enhancement in the pelvis at MR imaging.

To correlate magnetic resonance (MR) imaging findings of pelvic fluid, peritoneal enhancement, and peritoneal nodules with the presence of benign or malignant pelvic disease. Pelvic MR imaging findings in 87 women (mean age, 46 years) who subsequently underwent surgery were retrospectively reviewed. Phased-array multicoil, axial spin-echo T1-weighted MR images and axial fast spin-echo T2-weighted images were obtained. The largest pelvic fluid pocket was measured on the T2-weighted images in three orthogonal dimensions. Peritoneal enhancement and nodules were evaluated on gadolinium-enhanced MR images in 54 women. Pelvic fluid was shown in 21 of 25 patients with malignant neoplasms and 48 of 62 patients with benign disorders. Larger fluid pockets were associated with malignancy rather than with benign disorders, but there was substantial overlap. Use of peritoneal enhancement to diagnose peritoneal spread of tumor had a sensitivity, specificity, accuracy, and positive predictive value of 92% (11 of 12), 86% (36 of 42), 87% (47 of 54), and 65% (11 of 17), respectively. Use of peritoneal nodules for peritoneal spread had a higher specificity (90% [38 of 42]) and positive predictive value (69% [nine of 13]), although the sensitivity was lower (75% [nine of 12]). Large peritoneal fluid pockets are moderately predictive of malignancy or peritoneal spread of tumor. Peritoneal enhancement and enhancing peritoneal nodules are more sensitive and more specific.

Liver masses: replacement of conventional T2-weighted spin-echo MR imaging with breath-hold MR imaging.

To evaluate breath-hold magnetic resonance (MR) imaging with single-shot and multishot T2-weighted fast spin-echo (SE) and inversion-recovery (IR) SE echo-planar (EP) SE (IR-SE-EP) sequences compared with conventional T2-weighted SE imaging for detection of liver masses. Imaging with all sequences was performed in 32 patients on a 1.5-T whole-body system. Images were compared on the basis of lesion-to-liver contrast-to-noise ratio (C/N), lesion conspicuity, and image quality. Image analysis was performed by two experienced radiologists in consensus. Lesion-to-liver C/Ns were highest on fat-suppressed-half-Fourier-single-shot-fast-SE images. For solid lesions, the lesion-to-liver C/Ns were highest with IR-fast-SE, which was significantly better (P < .05) than IR-SE-EP and conventional SE techniques and also produced the best image quality. Sensitivity with IR-fast-SE was 96%; with fat-suppressed-half-Fourier-single-shot-fast-SE, 92%; with fat-suppressed-fast-SE, 89%; with IR-SE-EP, 83%; and with conventional SE, 78%. T2-weighted breath-hold imaging, particularly IR-fast-SE imaging, was more sensitive for hepatic masses than conventional SE imaging, with a substantial reduction in acquisition time. Half-Fourier-single-shot-fast-SE imaging was especially useful in patients who were unable to hold their breath.

Tarsometatarsal joint: anatomic details on MR images.

To evaluate the diagnostic capabilities of magnetic resonance (MR) imaging in the tarsometatarsal ([TMT] Lisfranc) joint with close anatomic correlation. Six normal cadaveric feet were imaged by using T1-weighted spin-echo (oblique axial) and three-dimensional spoiled gradient-recalled acquisition in the steady state ([SPGR] coronal, sagittal) sequences. Subsequently, gadolinium-enhanced arthrography was performed in three specimens followed by T1-weighted spin-echo and SPGR MR imaging. Specimens were sectioned in all three planes followed by correlation of the MR imaging results with gross anatomic findings. In all specimens, the oblique axial and, less effectively, the coronal and sagittal planes allowed visualization of the Lisfranc ligament. Intermetatarsal ligaments were seen almost exclusively on the coronal images, and TMT ligaments on the sagittal images. Bone alignment could be assessed on the oblique axial images. MR imaging reliably depicts the anatomy of the TMT joint including ligamentous and osseous structures.

Laryngeal carcinoma after radiation therapy: correlation of abnormal MR imaging signal patterns in laryngeal cartilage with the risk of recurrence.

To correlate abnormal magnetic resonance (MR) imaging signal patterns in cartilage with the effectiveness of radiation treatment. Eighty previously untreated patients underwent MR imaging and radiation therapy with a curative intent. Cartilage was considered to have an abnormal signal pattern if it had intermediate signal intensity on T1-weighted spin-echo (SE) MR images and high signal intensity on T2-weighted SE MR images. The minimum follow-up was 2 years. Abnormal MR imaging signal patterns of the thyroid cartilage (P < .001; P < .04) were more ominous than those of other cartilage. Abnormal signal patterns in cartilage of patients with small tumors (< 5 cm3 and especially < 1 cm3) were less significant. Abnormal signal patterns in cartilage combined with a large tumor (> 5 cm3) worsened the prognosis significantly (P < .05). Abnormal MR imaging signal patterns in cartilage may not indicate a poor prognosis in every case. Abnormal signal intensity in the thyroid cartilage combined with a tumor volume of > 5 cm3, however, appears to indicate an adverse prognosis with regard to tumor recurrence.

Mural thrombi in abdominal aortic aneurysms: MR imaging characterization--useful before endovascular treatment?

To evaluate magnetic resonance (MR) imaging accuracy in the characterization of mural thrombi in abdominal aortic aneurysms (AAAs). Forty-five patients (37 men, eight women; mean age, 68 years) with an AAA with mural thrombus thicker than 1 cm at sonography underwent T1- and T2-weighted spin-echo MR imaging. The thrombi were prospectively classified as one of three signal intensity (SI) categories: category 1 corresponds to low SI on both T1- and T2-weighted images; category 2, high SI on T1-and T2-weighted images; and category 3, inhomogeneous SI with hyperintense areas on both T1- and T2-weighted images. During surgery, thrombi were classified as organized, unorganized, and partially organized. MR imaging and surgical findings were compared. SI category 1 corresponded to organized thrombi in 24 of 24 patients. Category 2 corresponded to unorganized thrombi in 11 of 11 patients. In category 3, focal hyperintense areas corresponded (both for presence and location) to unorganized portions of partially organized thrombi in 10 of 10 patients. MR imaging is accurate in AAA thrombus characterization.

Predictive value of MR imaging-dependent and non-MR imaging-dependent parameters for recurrence of laryngeal cancer after radiation therapy.

To determine the predictive value of several clinical and radiologic parameters for recurrence of laryngeal cancer. Eighty previously untreated patients underwent magnetic resonance (MR) imaging before radiation therapy with curative intent. Tumor volume was calculated from T1-weighted MR images. Cartilage was considered invaded by pathologic tissue if it had intermediate signal intensity on T1-weighted spin-echo (SE) MR images and high signal intensity on T2-weighted SE MR images. The minimum follow-up was 2 years. Parameters such as age, sex, histopathologic findings, and invasion of the vocal muscle or pre-epiglottic space were not significantly correlated with tumor recurrence. Logistic regression analysis showed three relevant contributors: cord mobility, as judged clinically, and tumor volume and, more significantly, cartilage invasion, as seen at MR imaging. For untreated laryngeal cancer, MR imaging findings of tumor volume and cartilage invasion allow better patient selection for either radiation therapy or surgery. MR imaging is mandatory for T staging of laryngeal cancer.

Chronically stressed wrists in adolescent gymnasts: MR imaging appearance.

To investigate the magnetic resonance (MR) imaging appearance of a chronically stressed wrist and to assess the utility of MR imaging for evaluation of injuries to the growth plate. Coronal T1-weighted spin-echo and gradient-echo MR images were obtained of 93 wrists in 47 high-risk gymnasts of a Chinese opera school. MR imaging and radiographic findings were correlated in 93 wrists. The major MR imaging abnormalities of 47 radii with abnormal radiographic findings were horizontal fractures (n = 23), physeal cartilage extension to metaphysis (n = 17), and physeal widening (n = 17). The major MR abnormalities of 46 radii with normal radiographs included physeal cartilage extension (n = 12), metaphyseal bone bruise (n = 8), and vertical fractures (n = 4). Physeal cartilage extension into the metaphysis represents a healing sign in chronically stressed adolescent wrists. MR imaging findings including horizontal fracture and physeal cartilage extension to the metaphysis suggest that physeal widening occurred secondary to metaphyseal injury.

MRI demonstration of impairment of the blood-CSF barrier by glucose administration to the thiamin-deficient rat brain.

Contrast-enhanced T1-weighted spin-echo magnetic resonance imaging (MRI) has demonstrated that Gd-diethylenetriaminepentaacetate (Gd-DTPA), which normally does not cross the blood-brain or blood-CSF barriers, does so approximately 40 min after administration of glucose to a vitamin B1 deficient rat. The period of the onset of this blood-CSF or blood-brain barrier dysfunction coincides with our previous observations of accumulation of glutamate or glutamate derivatives following an equivalent glucose load under identical conditions of thiamin deficiency, consistent with a relationship between these two observations. The dysfunction was reversed when a thiamin deficient animal was made thiamin replete.

Capsular retraction of the liver in malignant tumor of the biliary tract MRI findings

Retraction of the liver capsule adjacent to a hepatic tumor is an unusual feature that has received little attention in radiological literature. We report two patients with pathologically proved malignant tumor of the biliary tract (one cholangiocarcinoma and one gallbladder cancer) in whom magnetic resonance imaging (MRI) showed retraction of the liver capsule to the tumors. MRI was performed at 1.0 T using a spin-echo (SE) technique, with T1 (TR/TE = 450/15 msec) and T2 (TR/TE = 2000/45 to 90 msec)-weighted images. Capsular retraction was seen on both T1- and T2-weighted SE MRI. Although capsular retraction of the liver adjacent to hepatic tumors is highly suggestive for epithelioid hemangioendothelioma, these two cases confirm that retraction of the liver capsule adjacent to hepatic tumors can be associated with other types of tumor, and especially with malignant tumors of the biliary tract.

Middle ear mucosal inflammation: an in vivo model.

The inflammatory process underlies the pathogenesis of otitis media (OM). Although knowledge concerning this common childhood disease continues to accumulate, most of the basic science research is based on in vitro or ex vivo methodologies. Magnetic resonance imaging (MRI), although lauded for its ability to image soft tissue, is often neglected as a research tool providing real-time in vivo information. This study attempts to assess experimental middle ear (ME) inflammation using MRI. The vasoactive effects of histamine and its interaction with antihistamines and a glucocorticoid were evaluated. Histamine was chosen because it is one of the naturally occurring inflammatory mediators. The antagonists were selected on the basis of their antihistaminic and vasoactive effects, respectively. Certainly there is substantial clinical interest in these agents because their efficacy for the treatment of OM is still being debated. The chinchilla model was chosen since it is one of the best characterized species in the study of OM. The three parts of the study are as follows: the effects of histamine on chinchilla ME mucosa; histamine challenge following pretreatment using hydroxyzine hydrochloride (H1 antagonist), ranitidine chloride (H2 antagonist), and the combination; and histamine challenge following pretreatment with dexamethasone. Sequential T1-weighted spin-echo (SE) MRI was used to detect extravasation of gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) into the middle ear effusion (MEE). The results indicate that the vasoactive effects of histamine are dose-related and can be assessed across a wide spectrum of histamine dosages inclusive of the human MEE levels. The H1 antagonist alone, or in combination with the H2 antagonist, was able to prevent the increased vascular permeability induced by histamine. When used alone, the H2 antagonist did not abolish the effects of histamine. The vasoactive effects of histamine were also ameliorated by pretreatment with a glucocorticoid. These findings indicate the utility of MRI for assessing mucosal inflammation in a real-time manner rather than as an accumulation of events. This study also validates the efficacy of an H1 antagonist and a glucocorticoid in counteracting the vasoactive effects of histamine. This methodology may be suited for evaluating the effects of other classes of antiinflammatory mediators.

MR imaging of breast implants.

Magnetic resonance (MR) images of 57 implants in 32 women were reviewed for possible complications. Spin-echo T2-weighted MR imaging of one or both breasts was performed with dedicated breast coils in axial, coronal, and sagittal planes. At surgery in 19 patients, MR evaluation for rupture correlated in 17 cases (two false-negative ruptures). Implant ruptures were seen at surgery in 15 of the 19 patients. Nine ruptures involved single-lumen implants: Six were ruptured within the fibrous capsule that normally forms around the foreign implant (intracapsular rupture [two were seen only at surgery]), and three were ruptured beyond this fibrous capsule into the soft tissues (extracapsular rupture). Five ruptures involved double-lumen implants, in which only the outer lumen had ruptured, and one involved a single-lumen saline implant that had completely collapsed. Additional complications of capsule formation and infection were suggested in two implants, and infection was suggested in one. The MR imaging appearances of the various types of implants as well as their complications are presented.

Fast spin-echo imaging of the knee: factors influencing contrast.

Conventional T2-weighted spin-echo magnetic resonance imaging of the knee requires a long TR. Fast spin-echo (FSE) imaging can improve acquisition efficiency severalfold by collecting multiple lines of k space for each TR. Compromises in resolution, section coverage, and contrast inevitably result. The authors examined the compromises encountered in FSE imaging of the knee and discuss the variations in image contrast and resolution due to choices of sequence parameters. For short TR/TE knee imaging, FSE does not appear to offer any advantages, since the increased collection efficiency for one section reduces the available number of sections, so that the total imaging time for a given number of sections remains constant relative to conventional spin-echo imaging. For T2-weighted images, considerable time can be saved and comparable quality images can be obtained. This saved time can be usefully spent on increasing both the resolution of the image and its signal-to-noise ratio, while still reducing total acquisition time by a factor of two. The preferred FSE T2-weighted images were acquired with a TR of 4,500 msec, TE of 120 msec, and eight echoes. The available number of sections is compromised, and the sequence remains sensitive to flow artifacts; however, the FSE sequence appears to be promising for knee imaging.

Cardiac abnormalities: assessment with T2-weighted turbo spin-echo MR imaging with electrocardiogram gating at 0.5 T.

To evaluate the cardiovascular system with magnetic resonance (MR) imaging performed with the turbo spin-echo (TSE) method and electrocardiogram (ECG) gating. ECG-gated T2-weighted TSE images were obtained in 52 patients with 68 pathologic conditions (intracardiac [n = 18], myocardial [n = 23], pericardial [n = 6], paracardial [n = 10], or aortic [n = 11] disease) and 10 healthy subjects. In healthy subjects, TSE parameters were tested and optimized, and signal-to-noise ratios (S/Ns) and contrast-to-noise ratios (C/Ns) were determined. Delineation of the endo-, epi-, and pericardial borders and signal intensity characteristics of myocardium, fat, pericardium, blood flow, tumors, and clots were assessed. The TSE method provided good-quality T2-weighted images with sharp edge definition in a short imaging time. Increasing the turbo factor reduced motion artifacts and preserved the S/N and C/N. TSE images also helped in diagnosis of tumors, pleural effusions, inflammatory changes, and intravascular clots. TSE MR imaging is a feasible alternative to time-consuming conventional SE MR imaging, reduces motion artifact, and may help in evaluation of the cardiovascular system.

Liposarcoma of the extremities: MR and CT findings in the histologic subtypes.

The findings on images of liposarcomas of the extremities in 48 patients (26 men and 22 women aged 20-85 years) were reviewed to correlate the histologic subtypes with radiologic appearance. Computed tomographic scans were obtained in 36 patients; magnetic resonance (MR) images, in 27 patients. The study group had 19 myxoid, 12 well-differentiated, nine round cell, and eight pleomorphic liposarcomas. Well-differentiated liposarcomas were predominantly composed of fat, typically with thick septa, which were hyperintense on T2-weighted spin-echo MR images. The heterogeneity of tumor helped differentiate tumor subtypes. Eleven of 19 myxoid tumors were mildly heterogeneous. Round cell and pleomorphic subtypes, which tend to be aggressive, were generally heterogeneous. Well-differentiated liposarcomas may be confidently differentiated from other subtypes of liposarcoma. Except for the well-differentiated subtypes, liposarcomas often contain no fat. Moderate to marked heterogeneity is common in high-grade liposarcomas; myxoid liposarcomas tend to be homogeneous and may mimic cysts.

Hepatocellular carcinoma: correlation of MR imaging and histopathologic findings.

Seventy-two histologically proved nodular hepatocellular carcinomas (HCCs) were studied with magnetic resonance (MR) imaging at 1.5 T. Capsules were present in 56 of the 72 tumors. Thirty-seven capsules were depicted on T1-weighted spin-echo MR images, and 16 were depicted on T2-weighted MR images. Visualization was dependent on thickness and structure of the capsules. Of the 72 tumors, 36 had a mosaic pattern. A mosaic pattern was visualized in 12 of the 36 tumors on T1-weighted images and in 27 of the 36 tumors on T2-weighted images. Six tumors were determined to be histologic grade 1, and all were hyperintense on T1-weighted images, regardless of whether intracellular fat deposits were present. Four of the six grade 1 tumors were isointense on T2-weighted images. In contrast, grades 2 and 3 tumors had various signal intensities on T1-weighted images and most were hyperintense on T2-weighted images. Twenty-one of 32 tumors (66%) with focal areas of increased signal intensity on T2-weighted images had intratumoral dilated sinusoids at histologic examination.

Hepatic metastases: CT versus MR imaging at 1.5T

A prospective multi-institutional study was performed to compare the sensitivity of computed tomography (CT) and high-field magnetic resonance (MR) imaging (1.5T) in the detection of hepatic metastases. T1-weighted and 72-weighted spin-echo (SE) MR images were compared with noncontrast, dynamic, and delayed CT. Sixty-nine oncology patients were studied. Noncontrast CT showed an overall sensitivity of 57%, dynamic CT 71%, delayed CT 72%, T1-weighted SE MR 47%, and T2-weighted SE MR 78%. Although there was no statistically significant (p less than 0.05) difference among dynamic CT, delayed CT, and T2-weighted SE MR, these three methods were significantly more sensitive (p less than 0.005) than noncontrast CT or T1-weighted SE MR. T2-weighted SE MR was significantly more sensitive (p less than 0.006) than CT or T1-weighted SE MR in the detection of small (less than 1 cm) lesions. CT was more sensitive in the detection of extrahepatic disease. These data confirm the superiority of T2-weighted SE over T1-weighted SE pulse sequences at 1.5T.

Magnetic resonance appearance of fibromatosis

We reviewed retrospectively the magnetic resonance (MR) images of 14 soft-tissue lesions of fibromatosis (desmoid tumors) encountered in 11 patients. The lesions were typically inhomogeneous in texture and round to oval in configuration. Margins were well-defined in 78% of the lesions at presentation and were infiltrating in all recurrences. On T1-weighted spin echo MR images, the predominant signal intensity was either isointense or minimally hyperintense when compared with skeletal muscle. On T2-weighted MR images the predominant signal intensity was typically intermediate between skeletal muscle and subcutaneous fat or isointense to fat. Linear and curvilinear areas of decreased signal intensity were distributed throughout the lesions on both pulse sequences in 86% of cases. This pattern strongly suggested fibromatosis. Speculation concerning possible etiologies of this appearance are discussed, and the relevant literature on previously reported cases is reviewed.

Comparison of spin echo T 1-weighted and FLASH 90° gadolinium-enhanced magnetic resonance imaging in the detection of cerebral metastases

A direct comparison of post-gadolinium FLASH 90 degrees magnetic resonance (MR) images against conventional post-gadolinium T1-weighted spin echo MR images obtained in patients with suspected cerebral metastatic disease shows the FLASH sequence to be inferior. False negative FLASH 90 degrees gadolinium-enhanced MR scans are thought to be a result of either magnetic susceptibility artefact or inferior contrast resolution. False positive FLASH 90 degrees gadolinium-enhanced MR images are a result of either difficulty in interpreting the high signal seen in small vessels or, again, magnetic susceptibility effects. In addition, our study shows small abnormalities suggestive of cerebral metastases on the FLASH 90 degrees gadolinium-enhanced sequences which were not seen on the spin echo T1-weighted gadolinium-enhanced sequences. We believe that spin echo T1-weighted gadolinium-enhanced MR sequences demonstrated 131 out of 139 (94.2%) and FLASH 90 degrees gadolinium-enhanced MR sequences detected 122 out of 139 (87.8%) possible metastases. From this, we conclude that spin echo T1-weighted gadolinium-enhanced MR sequences is a better test than FLASH 90 degrees gadolinium-enhanced MR in the diagnosis of brain metastases and that either sequence alone is limited as a screening test.

Definitive diagnosis of hepatic hemangiomas: MR imaging versus Tc-99m-labeled red blood cell SPECT.

Thirty-seven patients with 69 suspected hemangiomas found by means of computed tomography (CT) and/or ultrasound were studied with both 0.5-T magnetic resonance (MR) imaging and single photon emission CT (SPECT) with technetium-99m-labeled red blood cells. Using a criterion of "perfusion-blood pool mismatch," SPECT readers diagnosed 50 of 64 hemangiomas and all five "nonhemangiomas" (sensitivity, 78% [95% confidence interval, 0.664 - 0.864]; accuracy, 80% [0.69 - 0.877]). Qualitative analysis of lesion signal intensity on T2-weighted spin-echo MR images allowed readers to diagnose 58 of 64 hemangiomas and four of five nonhemangiomas (sensitivity, 91% [0.814 - 0.96]; accuracy, 90% [0.807 - 0.951]). Because of the significantly higher cost of MR imaging and its inability to categorically differentiate hemangiomas from hypervascular metastases, the authors consider SPECT to be the method of choice for diagnosing hepatic hemangiomas. MR imaging should be reserved for the diagnosis of lesions smaller than 2.0 cm and for those 2.5 cm and smaller adjacent to the heart or major hepatic vessels; in such cases MR imaging was found superior to SPECT.

Hepatic cirrhosis and hepatitis: MR imaging enhanced with superparamagnetic iron oxide.

Superparamagnetic iron oxide was applied as a reticuloendothelial contrast agent in the diagnosis of cirrhosis and hepatitis in seven patients. Three patients had compensated cirrhosis, and four had active hepatitis. T1- and T2-weighted spin-echo magnetic resonance images were obtained before and 1 hour after the administration of iron oxide. Eight patients without diffuse liver disease served as a control group. Normal liver tissue showed a 75% +/- 9% reduction in signal intensity after the administration of iron oxide, and the liver appeared homogeneously hypointense. Cirrhotic liver tissue showed a smaller response (P less than .05) to iron oxide, with a 52% +/- 13% reduction in liver signal intensity. Inhomogeneous structures could be observed in enhanced images and are thought to represent fibrous bands or regenerating nodules. Liver tissue with active hepatitis showed a markedly reduced response to iron oxide (11% +/- 2%) (P less than .05), and the parenchyma appeared homogeneous. The authors conclude that the uptake of iron oxide particles is inhomogeneously altered in cirrhosis because of structural changes and homogeneously decreased in hepatitis because of functional changes of hepatic parenchyma.