Non-breath-hold fast spin-echo versus breath-hold fast spin-echo and spoiled gradient-recalled echo MR imaging in the detection of hepatic tumors: correlation with surgical findings

OBJECTIVE: Our objective was to compare the sensitivity of non-breath-hold T2-weighted fast spin-echo with and without fat suppression, breath-hold T2-weighted fast spin-echo without fat suppression, and spoiled gradient-recalled echo (GRE) MR imaging for detecting hepatic tumors using surgical findings as the standard of reference. SUBJECTS AND METHODS: Eighteen patients with 36 surgically proven hepatic tumors had non-breath-hold T2-weighted fast spin-echo (6000/117 [TR/effective TE; echo train length, 16) MR imaging with and without fat suppression, breath-hold T2-weighted fast spin-echo MR imaging (2700/105; echo train length, 20), and spoiled GRE images (10.1/1.9; flip angle, 30 degrees) obtained before and after injection of a gadolinium chelate. Images were analyzed separately by two independent readers, with disagreements resolved by consensus reading. RESULTS: Non-breath-hold T2-weighted fast spin-echo MR imaging with and without fat suppression depicted 22 (61%; 95% confidence interval [CI], 43-77%) and 20 (56%; 95% CI, 37-72%) of 36 hepatic tumors, respectively. Breath-hold T2-weighted fast spin-echo imaging allowed detection of 19 (53%; 95% CI, 35-69%) of 36 hepatic tumors. Unenhanced and gadolinium chelate-enhanced spoiled GRE images allowed depiction of 18 (50%; 95% CI, 33-67%) and 29 (81%; 95% CI, 63-91%) of 36 hepatic tumors, respectively. Gadolinium chelate-enhanced spoiled GRE images allowed depiction of significantly more hepatic tumors than any of the other pulse sequences. CONCLUSION: Gadolinium chelate-enhanced spoiled GRE imaging is more sensitive than T2-weighted MR imaging obtained with a breath-hold or a non-breath-hold technique.     

T2-weighted breath-hold MRI of the liver at 1.0 T: comparison of turbo spin-echo and HASTE sequences with and without fat suppression

To compare the clinical usefulness of T2-weighted breath-hold sequences for imaging the liver, 33 patients with 97 focal hepatic lesions were studied with a 1.0-T scanner by using T2-weighted breath-hold turbo spin-echo (SE) sequences and T2-weighted breath-hold half-Fourier single-shot turbo SE (HASTE) sequences with and without fat suppression. Images were quantitatively analyzed for liver signal-to-noise ratio (SNR) and lesion-to-liver contrast-to-noise ratios (CNR). Qualitative analysis was performed for lesion conspicuity, motion artifacts, and anatomic sharpness of extrahepatic structures. Breath-hold turbo SE imaging with fat suppression showed the highest CNR for cystic lesions and the best lesion conspicuity for cystic and solid lesions among the four sequences. For solid lesions, there was no significant difference of lesion-to-liver CNR between them. HASTE sequence was superior to turbo SE sequences in terms of motion artifacts; however, the usefulness for evaluating focal hepatic lesions was limited compared with turbo SE sequence with fat suppression. Addition of fat suppression was not helpful for HASTE imaging because of decreased lesion conspicuity and extrahepatic details without the advantage of reducing motion artifacts. This study suggests that turbo SE sequence with fat suppression is most useful for breath-hold T2-weighted liver imaging at 1.0 T. Addition of imaging without fat suppression can be considered for evaluating extrahepatic structures. HASTE sequence may have a role for imaging uncooperative patients due to absence of motion artifacts.     

Islet cell tumors: comparison of dynamic contrast-enhanced CT and MR imaging with dynamic gadolinium enhancement and fat suppression

Ten patients with 11 islet cell tumors underwent dynamic contrast material-enhanced computed tomography (CT) and magnetic resonance (MR) imaging within a 1-month period. MR imaging depicted all 11 tumors, and CT depicted seven of the 11 tumors. CT did not depict four of seven tumors that measured 2.5 cm in diameter or less. Islet cell tumors had low signal intensity on T1-weighted fat-suppressed MR images, and gastrinomas were best shown with this technique. Two of three insulinomas less than 1.5 cm in diameter were best shown on dynamic contrast-enhanced fast low-angle shot (FLASH) images as uniform areas of high signal intensity. Hepatic metastases were seen in five patients and showed peripheral ringlike enhancement best demonstrated on dynamic gadolinium-enhanced FLASH images. Hepatic lesions were most conspicuous on T2-weighted fat-suppressed spin-echo images. MR imaging with dynamic gadolinium enhancement and fat suppression is a promising tool in the investigation of islet cell tumors.     

Contrast-enhanced endoscopic ultrasonography in pancreatic diseases: a preliminary study

OBJECTIVE: The purpose of this study was to clarify the usefulness of contrast-enhanced endoscopic ultrasonography in pancreatic diseases. METHODS: The subjects comprised 37 patients with pancreatic diseases: 11 with ductal cell carcinoma, 10 with mucin-producing tumor, five with pseudo-cyst, four with islet cell tumor, four with chronic pancreatitis, and three with serous cystadenoma. After endoscopic ultrasonography, Albunex (0.22 ml/kg) was injected intravenously at a rate of 1 ml/s into the right median vein, and observation was continued for 10 min. The presence or absence of enhancement of the lesion was determined in each disease. Because all the patients with ductal cell carcinoma, islet cell tumor, chronic pancreatitis, and serous cystadenoma, as well as five with mucin-producing tumor and three with pseudo-cyst, underwent angiography, vascularity was compared between angiographic images and those of contrast-enhanced ultrasonography. RESULTS: Enhancement of the lesion was observed in all patients with islet cell tumor and serous cystadenoma, in eight with mucin-producing tumor, and in three with chronic pancreatitis. However, no enhancement effect was observed in the patients with ductal cell carcinoma and those with pseudo-cyst. Comparison between the images of contrast-enhanced endoscopic ultrasonography and angiographic images showed three patients in whom angiograms were hypovascular, but enhancement effect was observed on ultrasonographic images. CONCLUSION: The combined evaluation of plain and enhanced images of endoscopic ultrasonography may be useful for the diagnosis of pancreatic diseases.     

Twenty years of research on B-cell chronic lymphocytic leukemia

The typical MRI features of the most common pancreatic diseases, such as pancreatitis and adenocarcinoma of the pancreas, have been established. However, even in these common pancreatic disorders, MRI correlation with the underlying pathology is limited for clinical reasons. We emphasize MR-pathological correlation of inflammatory and neoplastic pancreatic changes, including pancreatitis, adenocarcinoma, acinar cell carcinoma, rare cystic and solid pancreatic neoplasms, and islet cell tumors. By highlighting the correlation of key pathological features with MR findings, a better understanding of the MR appearance of pancreatic pathology can be provided. In addition, MRI may prove a powerful tool in detection and characterization of pancreatic tumors.     

Cerebellar deficient folia (cdf): a new mutation on mouse chromosome 6

OBJECTIVE: To discuss the case of an 8-yr-old boy with an aneurysmal bone cyst of the right proximal humerus, including the features imaged on plain film radiography, computed tomography (CT), magnetic resonance imaging (MRI), including spin echo and fast field echo imaging. CLINICAL FEATURES: The patient suffered for 1 yr from intermittent but progressive pain in his right upper arm and shoulder area. There was no history of trauma or known systemic disease. There was decreased range of motion in abduction of the glenohumeral joint and pain on focal pressure along the deltoid muscle. A complete imaging evaluation consisting of plain film radiography, CT and MRI was performed, which revealed the classical imaging features of an aneurysmal bone cyst. An additional cystic lesion was detected by the MRI that was not appreciated on the plain films or CT. INTERVENTION AND OUTCOME: The patient was referred for biopsy to confirm the preliminary diagnosis of aneurysmal bone cyst. No treatment was instituted. CONCLUSION: Evaluation of aneurysmal bone cyst may be completed with CT scanning and more specifically with MRI MRI coronal T2, weighted images are advantageous for visualization of the main cystic lesion and any additional cysts. Fast field echo images show a better contrast between the cyst and bone marrow with extension of the cyst into the epiphysis as evident in this case. Follow-up studies revealed complete healing of the cyst with only residual densities in the humeral metaphyseal area.     

Acinar pancreatic tumor with metastatic fat necrosis: report of a case and review of rheumatic manifestations

This report deals with a pancreatic tumor associated with metastatic fat necrosis. Our patient displayed the full gamut of nodular panniculitis, polyarthritis, fever, eosinophilia, hyperlipasemia, lytic bones lesions, and marrow fat necrosis. The rheumatologic features are reviewed. Elevated serum lipase is a most helpful laboratory confirmation. The tumor in our patient presented a difficult problem in classification. Although the appearance under light microscopy was most compatible with islet cell carcinoma or islet cell carcinoid, the ultrastructural characteristics were those of acinar carcinoma.     

Renal cell carcinoma: preoperative assessment for enucleative surgery with angiography, CT, and MRI

PURPOSE: Our purpose was to assess various imaging methods in detecting a pseudocapsule of renal cell carcinoma (RCC), which is critical for successful tumor enucleation. METHOD: In 42 patients with histopathologically proven RCC, images obtained at angiography (n = 42), CT (n = 30), and MRI (n = 19) were investigated retrospectively. All patients underwent treatment (enucleation: n = 15; nephrectomy: n = 27). The imaging criteria for the presence of a pseudocapsule were as follows: a surrounding radiolucent rim on angiography, a low or high density rim on CT, and a low intensity rim on MRI. All images were retrospectively reviewed by three radiologists without knowledge of the clinical and histological findings. RESULTS: Thirty-three of 42 RCCs showed a pseudocapsule on the surgical specimen. A pseudocapsule was detected in 67% of tumors (22/33) on angiography, 26% (6/23) on CT, 27% (4/15) on T1-weighted MRI, 93% (14/15) on T2-weighted MRI, 67% (8/12) on dynamic enhanced T1-weighted MRI, and 15% (2/13) on delayed enhanced T1-weighted MRI. CONCLUSION: T2-weighted MR images are superior for visualizing a pseudocapsule of RCC and for providing reliable selection criteria for tumor enucleation.     

Malignant lesions of the liver identified on T1- but not T2-weighted MR images at 1.5 T

The authors reviewed their 2 1/2-year experience with a magnetic resonance (MR) imaging protocol for a 1.5-T MR imager that included T2-weighted fat-suppressed spin-echo, T1-weighted breath-hold gradient-echo, and serial dynamic gadolinium-enhanced T1-weighted gradient-echo imaging to identify histologic types of malignant liver lesions more apparent on T1- than on T2-weighted images. MR images of 212 consecutive patients with malignant liver lesions were reviewed. T2-weighted, T1-weighted, and dynamic contrast-enhanced T1-weighted images were examined separately in a blinded fashion. Seven patients demonstrated liver lesions (lymphoma [two patients] and carcinoid, hepatocellular carcinoma, colon adenocarcinoma, transitional cell carcinoma, and melanoma [one patient each]) on T1-weighted images that were inconspicuous on T2-weighted images. In all cases, the lesions were most conspicuous on T1-weighted images obtained immediately after administration of contrast agent. Histologic confirmation was present for all seven patients. The consistent feature among these lesions was that they were hypovascular, due either to a fibrous stroma or to dense monoclonal cellularity. These results suggest that in some patients with hypovascular primary neoplasms, the lesions may be identified only on T1-weighted images, and that immediate postcontrast T1-weighted images are of particular value in demonstrating lesions.     

Zoo-FISH delineates conserved chromosomal segments in horse and man

PURPOSE: Evaluation of dynamic Gd-DTPA enhanced MR imaging in the staging of bladder cancer. METHODS: We studied 40 patients with histologically proven bladder cancer. All patients were examined with routine T1- and T2-weighted MRI and late Gd-DTPA enhanced T1-weighted MRI. Additionally, a dynamic study was performed with 10 subsequent short FLASH-2-D gradient echo sequences without delay immediately after bolus injection of Gd-DTPA. Signal intensities of the tumour and of the surrounding tissue as well as image contrast parameters were quantified. RESULTS: The dynamic study showed a higher accuracy in the evaluation of stage pTa to pT2 cancer compared to spin echo MRI (63% and 46%, respectively) and no difference regarding the sensitivity (87.5%). However, overstaging was a problem with both modalities. The contrast-to-noise ratio of bladder tumour and muscle was equal or significant higher with the dynamic study compared to spin echo MRI. A higher signal-to-contrast ratio of bladder tumour and bladder muscle was calculated for the dynamic study compared with the spin-echo MRI (p < 0.01; Mann-Whitney U test). CONCLUSION: Dynamic Gd-DTPA enhanced MRI is recommended to be used additionally in the preoperative staging of bladder neoplasms.     

Fast RARE MR imaging with variable flip angle excitation

A method was developed for performing T1-weighted magnetic resonance imaging with the rapid acquisition with relaxation enhancement (RARE) sequence by altering the excitation flip angle. This method was called variable flip angle turbo spin-echo (VF-TSE) imaging. When the effective echo time corresponds to the first echo, the resolution worsens as the echo train length becomes longer. For this reason, the echo train length was set at three, the repetition time (TR) was shortened (100- 200 msec) to decrease imaging time, and the initial flip angle was adjusted (120 degrees-140 degrees) to improve image quality. Another advantage of this method is that the initial flip angle can be reduced to below 90 degrees when a longer TR is needed. Measured signal intensities for VF-TSE imaging matched theoretic predictions. VF-TSE imaging yielded high contrast-to-noise and signal-to-noise ratios without sacrificing resolution. The VF-TSE technique was useful for breath-hold, three-dimensional, and cardiac synchronization imaging.     

Brain functional MRI of the visual cortex with echo planar imaging

Brain functional MR imaging (fMRI) is a non invasive imaging method for detecting neural activity. We performed functional MRI of the visual cortex with gradient-echo echo planar imaging (GE-EPI) and spin-echo EPI (SE-EPI) using 1.5T MRI system. Visual stimuli was performed with a checkerboard patterns. Magnitude and temporal phase of correlation between each pixel's time-course and sine functions at the frequency of the stimulus was calculated. In all subjects, the activation area in visual cortex obtained from SE-EPI was smaller than that from GE-EPI. Temporal phase delay images from both GE-EPI and SE-EPI showed signal spread from the primary visual cortex to peripheral supplementary areas. Temporal phase analysis is important to discriminate the source of the hemodynamic response to neural activation in fMRI.     

Ethnic variation of twinning rates in Malawi

To examine the usefulness of magnetic resonance imaging (MRI) in the preoperative determination of cancerous invasion, we examined 39 patients with advanced colorectal cancer with 0.5T MRI. We employed short inversion time inversion recovery (STIR) sequences, in addition to ordinary spin echo sequences for T1- and T2-weighted images. Preoperatively, the estimated depth of tumor invasion was classified into three grades according to MRI findings, and confirmed on the basis of surgical and histopathologic results. The depth of tumor invasion estimated preoperatively using STIR sequences corresponded well with the surgical and histopathologic results in 85% of the cases. In contrast, assessments based on T1-weighted images corresponded well in only 62% of the cases and T2-weighted images corresponded well in only 64%.     

Invasive breast carcinoma: analysis of dynamic magnetic resonance imaging enhancement features and cell proliferative activity determined by DNA S-phase percentage

BACKGROUND: There is little information regarding associations between magnetic resonance imaging (MRI) enhancement and biologic parameters of breast carcinoma. A prospective study was undertaken to correlate MRI dynamic contrast enhancement features with cell proliferative activity, as determined by DNA S-phase percentage. METHODS: Seventeen patients with invasive breast cancer underwent MRI at 1.5 tesla using a dynamic gadolinium-enhanced spoiled gradient recall echo technique. DNA analysis of samples of the excised lesions was then performed using flow cytometry. RESULTS: Invasive carcinomas with high DNA S-phase percentages (> or = 6.9%, the median value in this study), a measure of increased cell proliferation, were associated with a peripheral MRI enhancement pattern in 4 of 6 (67%) lesions compared with 0 of 11 carcinomas with lower DNA S-phase percentages (< or = 6.9%) (P = 0.006). There was no significant association between a high DNA S-phase percentage and greater MRI enhancement amplitude, rate, or washout. There was no significant association between aneuploid DNA content and any MRI enhancement feature. CONCLUSIONS: Increased cell proliferation in invasive breast carcinoma, as determined by high DNA S-phase percentage, is significantly associated with a peripheral MRI enhancement pattern but unrelated to greater MRI enhancement amplitude, rate, or washout.     

Improved coverage in dynamic contrast-enhanced cardiac MRI using interleaved gradient-echo EPI

An interleaved gradient-echo echo-planar imaging (IGEPI) sequence was modified for and applied to dynamic contrast-enhanced imaging of the heart. Using IGEPI, images with 3.0 x 3.9 mm nominal in-plane resolution are acquired in 100 ms, enabling eight slices per heartbeat for a heart rate of 60 beats/min. The acquisition speed and use of saturation prepulses allows acquisition of short- and long-axis images during the same contrast bolus. IGEPI maintains the acquisition characteristics required for performing a quantitative first-pass perfusion analysis as well as providing improved coverage compared with conventional fast gradient echo.     

Low-field magnetic resonance imaging (0.2 T) of tendons with sonographic and histologic correlation. Cadaveric study

RATIONALE AND OBJECTIVES: The authors evaluate the role of low-field strength magnetic resonance imaging (MRI) compared with sonography in the evaluation of degenerative changes of tendons, with histologic correlation, based on investigations of horse cadavers. METHODS: Low-field MRI and sonography was performed in 42 hours specimens for the evaluation of tendons and ligaments. Magnetic resonance imaging included sagittal and axial T1-weighted, T2-weighted, and gradient echo images. Sonography and MR images were evaluated for degenerative changes or tears and the findings were correlated with the histologic results. RESULTS: Using histologic findings as a gold standard, the accuracy for the sonographic evaluation was 65.9%, sensitivity was 16.7%, and specificity was 100%. The corresponding data for low-field MR imaging were 70.5% accuracy, 44.4% sensitivity, and 88.5% specificity. CONCLUSIONS: Low-field MRI investigation allows more accurate staging of tendinous changes than sonography. It is more reproducible and potentially includes the advantages of the combined evaluation of bones, ligaments, and soft tissue.     

Comparison of radiography, computed tomography and magnetic resonance imaging in the detection of sacroiliitis accompanying ankylosing spondylitis

OBJECTIVE: To compare magnetic resonance (MR) imaging, computed tomography (CT), and radiography in the detection of sacroiliitis accompanying ankylosing spondylitis (AS). DESIGN AND SUBJECTS: Nine volunteers and 24 patients were recruited. Radiography, CT, and MR imaging were completed within a 1-week period in 24 patients with AS. In precontrast MR examination, spin-echo T1, fast spin-echo T2, and gradient echo with rephasing T2* images were obtained without fat saturation using a 0.3-T imager for all volunteers and patients. Postcontrast MR examination was performed using the same precontrast SE T1 sequence for patients with AS. RESULTS AND CONCLUSIONS: MR imaging directly showed the normal cartilage in all 16 sacroiliac joints of the 8 volunteers. In the 24 patients with AS, cartilage abnormalities were observed in 42 sacroiliac joints. More diagnoses of sacroiliitis were made using MR and CT imaging than using radiography (P < 0.001). Therefore, low-field-strength MR can be useful in detecting early sacroiliitis in patients with AS. MR imaging was able to reveal early cartilage changes and bone marrow edema, which could not be found by either CT or radiography.     

MRI in the diagnosis of osteoid osteoma

INTRODUCTION: Osteoid osteoma (OO) is a frequently encountered benign bone tumor, seen in young adults with male predominance. MATERIALS AND METHODS: Nine patients complaining of nonspecific extremity pain underwent MRI examination. The sequences obtained were T1 and T2 weighted spin-echo and T2 weighted gradient echo. A CT scan examination followed in all cases, exploring the region of the abnormal signal seen on MRI. The results of both examinations were compared. RESULTS: In six of the nine patients (66.6%) MRI showed evidence suggestive of osteoid osteoma, comparable that seen on CT scan. In three patients (33.3%), MRI showed a nonspecific and ill-defined bone marrow signal abnormality. CT cuts focused on those areas of signal abnormality showed the nidus. DISCUSSION: MRI is more sensitive than CT scan in detecting soft tissue and bone marrow abnormalities adjacent to an osteoid osteoma. This may produce a misleading aggressive appearance on MR images. CT scanning is more specific than MRI, by showing the nidus. In three patients studied, the nidus was only seen by CT, the other six osteoid osteomas were equally seen by CT and by MRI. In our study, MRI revealed abnormalities in all the cases. It was also highly specific for osteoid osteoma in 66.6%. CONCLUSION: MRI is very sensitive in detecting bone marrow and soft tissue abnormalities, and can suggest the diagnosis of OO in a good number of patients. In the remainder cases MRI guides the CT-scan. CT is more accurate and remains the definite examination for the diagnosis of OO, by showing the nidus.     

Fat-suppressing STIR sequences with and without contrast media in the MRT of ENT tumors

Fat-suppressed STIR (short TI inversion recovery) sequences were compared to plain and contrast-enhanced T1-weighted SE sequences of head and neck tumors. 19 patients underwent MR imaging on a 0.5 Telsa system (T5-II, Philips). STIR imaging parameters: TR/TE = 1000/20 ms, inversion pulse 100 ms. All films were read by four radiologists. The image quality was graded: score from 0 to 5, by means that grade 5 = optimal quality. Sensitivity was 89% in STIR, 96% in SE sequences. Tumor delineation was graded good in the enhanced T1-weighted and enhanced fat suppression images. The unenhanced imaging was superior in STIR (STIR/T1 = 2.8/2.43). The tumor contrast was best in contrast enhanced and plain STIR sequences (STIR contrast = 3.41), and in the contrast enhanced T1-weighted SE (3.33). STIR almost equaled T1 post-contrast in respect of tumour conspicuity, but the sensitivity was lower. STIR can be a supplement to SE, but cannot substitute T1 postcontrast. The combined use is expected to have the highest assessment value.