MR staging of bladder carcinoma: correlation with pathologic findings

Forty patients with bladder carcinoma were examined preoperatively by means of magnetic resonance (MR) imaging. In all patients, total cystectomy with enterocystoplasty and pelvic node dissection was performed. The surgical and pathologic findings were correlated with the MR findings. Extension through the deep muscle of the bladder wall was present in 20 of the 40 patients and was diagnosed with a sensitivity of 95% and a specificity of 95%. Extension to perivesical fat was present in 18 of 40 patients and was diagnosed with a sensitivity of 66% and a specificity of 100%. Invasion of the adjacent organs was present in nine of 40 patients and was diagnosed with a sensitivity of 44% and a specificity of 96%. On the basis of the MR findings, the tumor was correctly staged, according to the TNM classification, in 24 of 40 (60%) patients, tumor extension was overestimated in three of 40 (7.5%) patients, and tumor extension was underestimated in 13 of 40 (32.5%) patients. MR imaging has been shown to be accurate in identification of macroscopic lymph node involvement and deep muscle involvement. It appears to be at least as useful as computed tomography (CT) in the evaluation of perivesical fat involvement and to be superior to CT in the detection of invasion of adjacent organs. One limitation of MR imaging is in the evaluation of tumor extension into the periurethral glands.     

Urinary bladder MR imaging. Part II. Neoplasm

The potential of magnetic resonance (MR) imaging for the evaluation and staging of bladder tumors was analyzed in 15 patients (11 cases of transitional cell carcinoma, two adenocarcinomas, one leiomyosarcoma, and one leiomyoma). Neoplasms were characterized by size, site, and growth pattern, and the accuracy of the staging was compared with the results of computed tomography and pathologic study. Malignancies were accurately detected and staged by MR imaging in 12 of 14 patients (85%). Tumor site and degree of bladder distention did not adversely affect detection; tumors greater than 1.5 cm were detected easily. In situ carcinoma (stage Tis) was not detected on MR images. Imaging in both sagittal and transverse planes was needed for optimal bladder evaluation. Bladder carcinoma was best displayed with a short echo delay time (TE) of 28 msec and repetition (TR) times of 1.0-2.0 sec: TR = 1.0 gave 34% contrast and TR = 2.0 gave 36% contrast between tumor and surrounding urine. Bladder-wall invasion by tumor was best evaluated with long TR (2.0 sec) and long TE (56 msec) (82% contrast). For assessing tumor extension into perivesical fat, short TR (0.5 sec) and TE (28 msec) were optimal (58% contrast). MR imaging offers an increased sensitivity for tumor detection and promises to greatly improve the staging of bladder neoplasms.     

MR imaging of urinary bladder neoplasms

The diagnostic potential of magnetic resonance (MR) imaging at 1.5 T for assessment and staging of urinary bladder tumors was investigated in 10 patients with malignant urinary bladder tumors. All patients underwent complete pathologic staging. The appearance of the urinary bladder tumors and the ability to stage them by means of MR imaging was evaluated morphologically and compared with results obtained with pathologic examination. Magnetic resonance imaging permitted tumor localization in all patients. In nine patients the tumor stage was accurately determined by MR imaging. The smallest tumor detected by MR imaging was 1.5 cm. Both transverse and sagittal imaging planes were found to be essential for accurate assessment of tumor extension. Signal intensity data obtained from both dual and multi spin echo sequences showed that tumor display and depth of infiltration was best seen with a repetition time (TR) of 2,000 ms and an echo time (TE) of 90 ms. Accurate evaluation of perivesical tumor infiltration required a sequence with a TR 800 ms and a TE 30 ms. Data presented here further support the role of MR in staging urinary bladder neoplasms.     

MR cystography for bladder tumor detection

The purpose of the study was to assess the diagnostic performance of MR cystography with virtual cystoscopic and multiplanar reconstructions for detection of malignant bladder tumors. Thirty-two patients with 43 bladder tumors previously confirmed by cystoscopy (mean size 2.5 cm; 0.4–9.1 cm;) were examined at 1.5 T with a three-dimensional T2-weighted turbo spin echo sequence (TR=2911 ms, TE=500 ms, echo train length 256). Virtual cystoscopic reconstructions (VC) and multiplanar reconstructions (MPR) were obtained and analyzed separately by three radiologists without knowledge of the tumor location. Intraoperative or cystoscopic findings served as standard of reference. Sensitivities and specificities were calculated using a receiver-operating characteristic analysis with five levels of confidence. Area-under-curve values were similar for MPRs (0.952), VC (0.932) and the combination of both methods (0.954). Optimal sensitivity was 92.3% for MPR and 90.7% for VC, respectively, with a specificity of 91.1% for MPR and 90.4% for VC. The combination of MPR and VC resulted in a sensitivity of 90.7% and specificity of 94.0%. MR cystography is a promising, completely non-invasive technique for the detection of bladder lesions with a high diagnostic performance.     

Magnetic resonance with endorectal coil in the local staging of prostatic carcinoma. Comparison with histologic macrosections in 40 cases]

PURPOSE: Endorectal coil MRI is widely used in the diagnostic workup of prostate cancer, but diagnostic accuracy rates reported in the literature are quite variable. We report our personal experience with endorectal coil MRI in the local staging of prostate carcinoma. MATERIAL AND METHODS: Forty consecutive patients with histologically proved prostate carcinoma were examined with endorectal coil MRI at high field strength (1.5 T). All patients underwent a sagittal T1-weighted SE location sequence (TR 400, TE 20), an axial T1-weighted SE (TR 400, TE 20), two axial T2-weighted FSE sequences (TR 3000, TE 102, ETL 8) with and without fat suppression, and a coronal T2-weighted FSE sequence (TR 3000, TE 102, ETL 8); an axial Fast Multiplanar Spoiled Gradient Recalled (FMSPGR) dynamic sequence after Gd-DTPA injection was also performed in 18 patients. MR staging of local tumor spread was done according to the current literature criteria. All patients were submitted to radical prostatectomy, and histologic macrosections on the same plane as MR images were obtained from surgical specimens. MR and histologic staging were compared to assess MR accuracy in detecting capsular infiltration, seminal vesicles and apex involvement. The diagnostic yield of Gd-DTPA was also investigated. RESULTS: MRI correctly staged 31 of 40 cases (77.5%). MR accuracy was 80% in detecting capsular infiltration (85.7% sensitivity and 73.6% specificity), 90% in seminal vesicle involvement (91.6% sensitivity, 89.2% specificity) and 72.5% in apex involvement (79.1% sensitivity, 62.5% specificity). Dynamic studies with Gd-DTPA did not improve staging accuracy in any case. DISCUSSION AND CONCLUSIONS: In agreement with most of the current literature, MRI showed moderate overall accuracy in the local staging of prostate carcinoma. Particularly, MRI had good accuracy in detecting seminal vesicle involvement but moderate sensitivity and specificity in demonstrating capsular infiltration and apex involvement. Due to its high cost, MRI should not be routinely used in prostate cancer staging but should be reserved to the patients whose clinical and serological data suggest extraprostatic tumor spread, whose preoperative demonstration could avoid noncurative surgery.     

Acute injury of the ligaments of the knee: magnetic resonance evaluation

Eleven acutely injured knees and 13 normal knees were examined by magnetic resonance imaging (MRI) to assess the value of this modality in detecting acute ligamentous injury of the knee. The presence of torn ligaments in the injured knees was determined by arthroscopy and/or arthrotomy in ten cases and clinical follow-up in one case. The anterior and posterior cruciate ligaments (ACL and PCL) were demonstrated by sagittal spin echo (SE) images through the intercondylar notch (TE = 30 ms; TR = 2,000 ms). The tibial and fibular collateral ligaments (TCL and FCL) were evaluated on coronal SE images (TE = 30 ms, TR = 200 or 530 ms; TE = 120 ms, TR = 2,000 or 2,120 ms). The ACL and PCL were considered torn on MR if they appeared disrupted or were not seen in their normal anatomical positions. The collateral ligaments were considered torn if abnormal high-intensity signal was noted in adjacent soft tissues on TE = 120 ms images or if disruption of a ligament was apparent. Eleven of 15 torn ligaments and 80 of 81 normal ligaments were correctly identified by these criteria. It is concluded that MR imaging may be useful in detecting acute injury of ligaments of the knee.     

Lymph nodes of the neck. Diagnosis using magnetic resonance with gradient-echo technique

As for the pathologic conditions of neck lymph nodes, the clinician needs to know if the involved node is reactive, phlogistic, or neoplastic in nature. If accurate tumor staging is required, imaging techniques play a fundamental role. Our study was aimed at assessing the actual role of MR imaging in the evaluation of neck lymph node involvement. The study was performed using an MR Max Plus by General Electrics operating with an 0.5 T superconductive magnet. We employed gradient-echo (GE) pulse sequences with TR 500, TE 15 ms and 90 degrees flip angle for T1-weighted images, and with TR 500, TE 30 ms and 25-30 degrees flip angles for T2-weighted images; for Pd-T2-weighted images, TR was 520, TE 30 ms, and flip angles were 40-45 degrees. The results were correlated with histopathologic findings obtained at biopsy. The advantages of GE sequences were: 1) whole neck imaging--thus saving time, and reducing radiation dose and contrast media; 2) optimal anatomical and topographic evaluation of the lesion; 3) imaging of the longitudinal diameter of the node; 4) higher sensitivity for lymph node tissue modifications; 5) imaging of necrosis, hemorrhage, and/or fibrosis. GE sequences were especially useful for accurate tumor staging, in the follow-up, and to verify response to therapy. However, even though MR imaging has proven to have high sensitivity, its specificity was similar to that of contrast-enhanced CT. Further studies with the use of paramagnetic contrast media are needed to solve these problems.     

Incidence of adrenal masses in patients referred for renal artery stenosis screening MR

RATIONALE AND OBJECTIVES: Prior work has shown the efficacy of magnetic resonance (MR) in renal artery stenosis evaluation. The increasing role of renal artery stenosis in the differential diagnostic evaluation of hypertension raises the question of whether MR should be used as a screening modality. This project evaluated the additional potential benefits of MR by determining the incidence of adrenal masses in this selected population. METHODS: A 2-year retrospective study analysis of patients who failed to respond to antihypertensive medical management and were referred for renal MR for hypertension amassed 77 subjects ranging in age from 18 to 88 years. A masked analysis for adrenal masses was performed on this data set. Magnetic resonance techniques included T2-weighted turbo spin-echo (repetition time [TR] 2000-4000 ms, echo time [TE] 80-100 ms, turbo factor 2-16), T1-weighted spin-echo (TR 200-500 ms, TE 10-30 ms), gradient-echo time-of-flight (TR 26 ms, TE 6.9 ms, 40 degrees flip angle, 2 excitations), and dynamic gadopentetate dimeglumine-enhanced MR angiography (three-dimensional gradient recalled echo, TR 10 ms, TE 3 ms, 40 degrees flip angle, 1 excitation). RESULTS: Thirty-three patients had renal artery disease, 44 had normal renal arteries, and 7 had adrenal masses. Forty-three percent of patients who underwent renal MR had disease of the renal arteries detected, and 9% of patients referred for MR had adrenal masses that would have been missed with scintigraphy and/or angiography, of which 57% were responsible for hypertension. CONCLUSIONS: The ability to evaluate renal artery and adrenal anatomy globally can be useful, as exemplified in the current series, and the adrenals should be examined carefully in any renal MR in a hypertensive patient.     

Recurrent thyroid carcinoma: characteristics on MR images

Magnetic resonance (MR) imaging was used in 32 patients, including eight with benign disease, after partial or total thyroidectomy to determine sensitivity and specificity of MR imaging in the detection of tumor recurrence, to compare signal intensities of scar versus recurrent tumor qualitatively and quantitatively, and to define the extent of recurrent tumor. Findings from surgery (n = 23), needle biopsy (n = 1), or clinical follow-up (n = 8) were used for verification. Of 24 patients with primary thyroid carcinoma, 15 had recurrence and nine had a normal postsurgical thyroid bed. Diagnosis from MR images was correct in 20 cases, but false positive in three and false negative in one. Local recurrence was characterized by low to medium intensity on short repetition time (TR)/short echo time (TE) images and medium to high intensity on long TR/long TE images. Scar in the normal postsurgical thyroid bed showed low intensity on both short and long TR/TE images. Local recurrence of thyroid carcinoma and lymph node metastasis produced positive contrast compared with muscle on short TR/short TE (31 + 19%) and long TR/long TE (85 + 30%) images; fibrosis produced negative contrast, particularly on long TR/long TE (-56, -80%) images. These results indicate the capability of MR imaging in the evaluation of recurrence of thyroid tumors and in the differentiation of abnormal tissue due to tumor recurrence from postoperative fibrosis by means of signal contrast relative to a reference tissue.     

Signal characteristics of focal liver lesions on double echo T2-weighted conventional spin echo MRI: observer performance versus quantitative measurements of T2 relaxation times

PURPOSE: The purpose of this work was to evaluate the ability of expert readers to differentiate benign from malignant liver lesions based on visual assessment of lesion signal intensity on double echo T2-weighted conventional spin echo (CSE) MR images and to compare reader performance with quantitative measurements of T2 relaxation times. METHOD: Sixty-seven MR examinations demonstrating 85 liver lesions (37 hemangiomas, 32 malignancies, 15 cysts, and 1 focal nodular hyperplasia) on double echo T2-weighted CSE sequences (TR 3,600 ms/TE 50, 160 ms) were qualitatively reviewed by three independent readers. T2 relaxation times were calculated for each lesion. Receiver operating characteristic (ROC) analyses of expert readers were compared with calculated T2 relaxation times. RESULTS: T2 values performed significantly better than subjective reader analysis for liver lesion characterization (area under ROC = 0.93 vs. 0.81, 0.78, and 0.75; p < 0.0001). With use of a T2 threshold of 125 ms, the sensitivity of T2 values for malignant lesions was 100%, specificity 71%, and accuracy 84%. By comparison, the sensitivity of the three readers for malignant lesions was 76-83%, with a specificity of 61-72% and an overall accuracy of 71-80%. CONCLUSION: Despite expert reader analyses, subjective evaluations of liver lesion signal characteristics are prone to inaccuracy and lack certainty and consistency when intermediate TEs (50/160 ms) are used. Quantitative measurements of T2 relaxation times should be performed to accurately and confidently differentiate benign from malignant liver lesions. Use of a higher T2 threshold than previously recommended is required to avoid misclassification of malignancies.     

Magnetic resonance in the evaluation of parametrial involvement in carcinoma of the cervix uteri]

Cervical carcinoma is one of the most frequent gynecologic malignancies. Its prognosis depends on both tumor volume at diagnosis and its stage. Staging accuracy is important not only for prognosis but also for optimal treatment planning. According to FIGO criteria, carcinomas without parametrial involvement (stage I and limited stage IIA disease) can be surgically treated. For more advanced stages, treatment, in most cases, consists of radiation therapy or chemotherapy alone. The authors evaluated MR accuracy in the diagnosis of parametrial involvement; to this purpose, 32 patients with histologically proven lesions were referred for MR imaging, which was performed with a 0.5 T superconductive magnet. Transverse and sagittal SE images were obtained with T2 weighting (TR 1800 ms, TE 30-100 ms); transverse and sometimes sagittal images were obtained with T1 weighting (TR 450/300 ms, TE 20/30). T1-weighted images distinguished neoplasm from cervical stroma or dense parametrial connective tissue in 40% of cases only. T2-weighted images, instead, demonstrated the difference in all cases, showing tumor as a hyperintense area in 90% of patients. Neoplastic involvement of pericervical connective tissue was diagnosed, with those sequences, on the basis of focal disruptions of the outer hypointense fibrous cervical stroma; findings were correlated with those from a previous clinical staging and in 26/32 patients with pathologic findings. MR accuracy in demonstrating parametrial involvement was 88%, sensitivity was 77% and specificity was 94%. Clinical staging accuracy in the evaluation of this parameter was 66%. In 6 cases with no surgical findings, MR confirmed extensive parametrial and vesical or rectal neoplastic involvement, as diagnosed at clinics. MR imaging, thanks to its multiplanar and multiparametric imaging capabilities is a very reliable technique in the preoperative staging of cervical carcinoma. Moreover, since clinical staging can sometimes underestimate pericervical connective spread, the higher accuracy of MR imaging can help avoid useless interventional procedures.     

Free-breathing renal magnetic resonance angiography with steady-state free-precession and slab-selective spin inversion combined with radial k-space sampling and water-selective excitation.

The impact of radial k-space sampling and water-selective excitation on a novel navigator-gated cardiac-triggered slab-selective inversion prepared 3D steady-state free-precession (SSFP) renal MR angiography (MRA) sequence was investigated. Renal MRA was performed on a 1.5-T MR system using three inversion prepared SSFP approaches: Cartesian (TR/TE: 5.7/2.8 ms, FA: 85 degrees), radial (TR/TE: 5.5/2.7 ms, FA: 85 degrees) SSFP, and radial SSFP combined with water-selective excitation (TR/TE: 9.9/4.9 ms, FA: 85 degrees). Radial data acquisition lead to significantly reduced motion artifacts (P < 0.05). SNR and CNR were best using Cartesian SSFP (P < 0.05). Vessel sharpness and vessel length were comparable in all sequences. The addition of a water-selective excitation could not improve image quality. In conclusion, radial k-space sampling reduces motion artifacts significantly in slab-selective inversion prepared renal MRA, while SNR and CNR are decreased. The addition of water-selective excitation could not improve the lower CNR in radial scanning.     

Evaluation of the role of magnetic resonance myelography in lumbar spine imaging

The purpose of our study was to evaluate the accuracy of MR myelography in depicting disc herniation in the lumbar spine when compared with conventional MRI in patients presenting with clinical evidence of disc herniation. One hundred patients referred for conventional MR imaging of the lumbar spine also had coronal MR (TR 9000 ms, TE 272 ms eff, NEX 3, echo train length 32) myelography performed. Three experienced observers compared magnetic resonance myelography (MRM) with conventional lumbar spine MR using the following variables: visibility of thecal sac and nerve roots, and the presence, location and severity of disc herniation. Disc protrusions were seen at 110 disc space levels on conventional MR images as opposed to 93 on MRM. However, only 72 % of lesions seen on conventional MR were diagnosed by MRM. Similarly, only 63.8 % of nerve root compression abnormalities seen at conventional MR were visualized when compared with conventional MRM. The sensitivity, specificity and accuracy of MRM when compared with conventional MR was 72, 93 and 85 %, respectively. The MRM technique yields images that resemble conventional myelography and may be used to help confirm abnormalities seen on conventional MR in selected cases; however, the large number of false-positive and false-negative examinations indicates that caution should be used in interpreting MRM images. Received: 16 February 1998; Revision received: 25 May 1998; Accepted: 30 September 1998     

Infantile tuberous sclerosis changes in the brain: proton MR spectroscopy findings.

A parietal hamartoma of a three-month-old boy with tuberous sclerosis was studied with magnetic resonance (MR) imaging, and proton MR spectroscopy. MR spectra were obtained with the single-voxel PRESS (point resolved spectroscopy; TR = 1500 ms, TE = 135 ms) sequence, in a 8 cc region of interest. Apparently low NAA/Cho (0.28), and NAA/Cr (0.37) ratios were noted in the hamartoma, that could suggest a neoplasm. The lesion and the surrounding brain tissue were studied again after seven months with spectroscopic imaging using the chemical shift sequence (TR = 1500 ms. TE = 40 ms). This study revealed apparently improved NAA/Cho (2.63), NAA/Cr (2.13) ratios in the hamartoma compared to the initial examination at three months of age, excluding the possibility of a neoplasm.     

Combined gadolinium-enhanced and fat-saturation MR imaging of renal masses

Combined gadopentetate dimeglumine enhancement and fat-saturation (FS) spin-echo (SE) magnetic resonance (MR) imaging for the detection and characterization of renal masses was evaluated in 43 patients with a total of 71 lesions (28 solid masses and 43 cysts). SE MR sequences compared were the following: short repetition time (TR)/echo time (TE), conventional SE, short TR/TE FS SE, long TR/TE conventional SE, gadolinium-enhanced short TR/TE conventional SE, and gadolinium-enhanced short TR/TE FS SE techniques. MR findings were compared with findings of contrast-enhanced computed tomography (CT) and with pathologic findings in all patients. The sensitivities for detection of renal masses with gadolinium-enhanced FS (71 of 71 lesions) and with gadolinium-enhanced short TR/TE conventional (65 of 71 lesions) SE sequences were significantly (P less than .01) greater than with any unenhanced (short TR/TE conventional [40 of 71 lesions], or long TR/TE [39 of 71 lesions]) SE sequence. Lesion characterization was also best with the gadolinium-enhanced FS SE sequence (65 of 71 lesions correctly classified). When combined pre- and postcontrast short TR/TE FS SE images were analyzed with both qualitative (visual) and quantitative (region-of-interest measurements) assessment, lesion characterization improved even further (70 of 71 lesions were correctly characterized). All lesions detected with CT were visualized with the gadolinium-enhanced FS SE MR sequence, which in addition depicted seven cysts and two small renal cell carcinomas. In summary, the use of gadopentetate dimeglumine, especially when combined with the FS technique, was superior to unenhanced MR imaging for detection and characterization of renal lesions.     

Discrimination of benign from malignant hepatic lesions based on their T2-relaxation times calculated from moderately T2-weighted turbo SE sequence

The differentiation of hemangioma from other hepatic neoplasms using MRI usually relies on the evaluation of heavily T2-weighted images. The aim of this study was to assess the value of T2-relaxation times calculated from moderately T2-weighted turbo spin-echo (TSE) sequence in characterization of focal hepatic lesions, including hepatic malignancies, focal nodular hyperplasia (FNH), hemangioma, and cyst. Fifty-two patients with 114 proven lesions (61 malignant masses, 6 focal nodular hyperplasias, 28 hemangiomas, 19 cystic lesions) were examined on 1.5-T system using a double-echo TSE sequence (TR=1800 ms; TE(eff) 1=40 ms; TE(eff) 2=120 ms). Signal intensities (SI) of the liver as well as SI of all lesions were measured, and then the T2-relaxation times were calculated. The mean T2 time for the liver was 54 ms (+/-8 ms), for FNH 66 ms (+/-7 ms), for malignant hepatic lesions 85 ms (+/-17 ms), for hemangiomas 155 ms (+/-35 ms), and for cystic lesions 583 ms (+/-369) ms. Most malignant hepatic lesions were best differentiated between the thresholds of 67 and 116 ms, generating a sensitivity of 90% and a specificity of 94%. There were six false-negative diagnoses of malignant tumor and three false-positive cases (two hemangiomas and one FNH). Calculation of the T2-relaxation times obtained from the double-echo TSE sequence with moderate T2-weighting allowed differentiation between malignant and benign hepatic lesions with high sensitivity and specificity.     

MRI evaluation of the patellar articular cartilage in patients with subluxation of the patella

In patients with subluxation of the patella, injury of the patellar articular cartilage is frequently observed and correct evaluation is important to manage these patients. We examined 11 patients with subluxation of the patella and five normal volunteers. In 12 patellofemoral joints of seven patients with subluxation of the patella, the abnormalities observed on MRI were compared with those on arthroscopy and/or at operation. MRI was performed with a Magnetom 1.5 T (Siemens) using the round surface coil. Pulse sequences were SE (TR 400 ms/TE 19 ms), FLASH (TR 320 ms/TE 15 ms FA 90 degrees and 40 degrees), and SE (TR 2000 ms/TE 26, 70 ms). We analysed MR findings of the 12 abnormal joints and 10 normal joints according to the following classification of abnormalities observed on arthroscopy. (1) normal appearance (n = 3 joints), (2) softening and fibrillation (n = 6), (3) fragmentation (n = 3), and (4) erosion to bone (n = 0). In only one of the six cases with softening and fibrillation observed on arthroscopy, MRI could visualize the thickening of patellar articular cartilage, but in all three cases with fragmentation observed on arthroscopy, MRI could visualize the thin inhomogenous cartilage with irregular surface. The combination of SE (TR 400 ms/TE 19 ms) and FLASH (TR 320 ms/TE 15 ms FA 90 degrees) are extremely effective pulse sequence to detect the abnormalities of patellar articular cartilage. We conclude that MRI is a useful noninvasive method of detecting advanced changes in patellar articular cartilage.     

Brain tumor classification by proton MR spectroscopy: comparison of diagnostic accuracy at short and long TE

BACKGROUND AND PURPOSE: Different TE can be used for obtaining MR spectra of brain tumors. The purpose of this study was to determine the influence of the TE used in brain tumor classification by comparing the performance of spectra obtained at two different TE (30 ms and 136 ms). METHODS: One hundred fifty-one studies of patients with brain tumors (37 meningiomas, 12 low grade astrocytomas, 16 anaplastic astrocytomas, 54 glioblastomas, and 32 metastases) were retrospectively selected from a series of 378 consecutive examinations of brain masses. Single voxel proton MR spectroscopy at TE 30 ms and 136 ms was performed with point-resolved spectroscopy in all cases. Fitted areas of nine resonances of interest were normalized to water. Tumors were classified into four groups (meningioma, low grade astrocytoma, anaplastic astrocytoma, and glioblastoma-metastases) by means of linear discriminant analysis. The performance of linear discriminant analysis at each TE was assessed by using the leave-one-out method. RESULTS: Tumor classification was slightly better at short TE (123 [81%] of 151 cases correctly classified) than at long TE (118 [78%] of 151 cases correctly classified). Meningioma was the only group that showed higher sensitivity and specificity at long TE. Improved results were obtained when both TE were considered simultaneously: the suggested diagnosis was correct in 105 (94%) of 112 cases when both TE agreed, whereas the correct diagnosis was suggested by at least one TE in 136 (90%) of 151 cases. CONCLUSION: Short TE provides slightly better tumor classification, and results improve when both TE are considered simultaneously. Meningioma was the only tumor group in which long TE performed better than short TE.     

Vertebral osteomyelitis: assessment using MR

Thirty-seven patients who were clinically suspected of having vertebral osteomyelitis were prospectively evaluated with magnetic resonance (MR), radiography, and radionuclide studies. These findings were correlated with the final clinical, microbiologic, or histologic diagnoses. Based on the results of these latter studies, 23 patients were believed to have osteomyelitis. MR examinations consisted of at least a sagittal image (TE = 30 msec, TR = 0.5 sec) and an image obtained at TE = 120 msec, TR = 2-3 sec. All patients underwent radiographic and MR examinations, 36 underwent technetium 99m-HDP bone scanning, and 20 patients underwent gallium 67 scanning. Nineteen patients underwent both bone and gallium scanning. The imaging studies were reviewed independently by investigators blinded to the final diagnoses. MR had a sensitivity of 96%, specificity of 92%, and accuracy of 94%. Combined gallium and bone scan studies (19 cases) had a sensitivity of 90%, specificity of 100%, and accuracy of 94%. Bone scans alone had a sensitivity of 90%, specificity of 78%, and accuracy of 86%. Plain radiographs had a sensitivity of 82%, specificity of 57%, and accuracy of 73%. The MR appearance of vertebral osteomyelitis in this study was characteristic, and MR was as accurate and sensitive as radionuclide scanning in the detection of osteomyelitis.     

ESWAN序列参数对出血性剪切灶及脑静脉显示的影响和分析

目的研究多回波采集的增强T2*加权血管成像(ESWAN)序列的TR和TE参数对磁敏感效应的影响;调整更适合出血性剪切灶检出的ESWAN序列参数。资料与方法 10例弥漫性轴索损伤(DAI)患者经两种不同参数设置的ESWAN序列(两种序列的参数区别在于:短TE的ESWAN序列的首个回波TE 10 ms,TR 77 ms;长TE的ESWAN序列的首个回波TE 48 ms,TR 104 ms)扫描获得两组ESWAN图像,经后处理得到两组幅度图,将幅度图行最小强度投影(MinIP)后在两组图像上分别计数出血灶的数目、测量出血灶的容积,在三脑室上部及室间孔层面对显影的脑深部静脉计数。用配对t检验的方法检验两组数据的差异性。结果两组图像显示的微出血灶的数量及分布完全一致;长TE的ESWAN序列测量的微出血灶容积显著大于短TE的ESWAN序列;长TE的ESWAN序列显示的脑深部静脉数量明显多于短TE的ESWAN序列。结论 ESWAN序列的多回波采集优势,即使明显缩短首个回波的TE,后续的回波仍能保障对微出血灶检出的磁敏感效应;随着TE的延长,显影的静脉数量明显增多,但模糊效应也逐步放大,出血灶容积的放大比例也增加。对于脑外伤...