MR imaging of the breast with Gd-DTPA enhancement: comparison with mammography and ultrasonography.

The accuracy of MR imaging with Gd-DTPA enhancement was compared with mammography and ultrasonography in 52 patients with clinically palpable benign and malignant breast masses (36 carcinomas, 2 malignant phyllodes tumors, 7 fibroadenomas, 7 cysts). On dynamic MR imaging, carcinomas and fibroadenomas were discriminated by their different dynamic enhancement profiles. In carcinomas, signal intensity increased rapidly, reaching a peak or plateau within 2 min after the injection of contrast medium. In fibroadenomas, signal intensity showed a much slower continuous increase without ceasing until about 8 min after injection. Malignant phyllodes tumors showed a dynamic enhancement profile identical to that of benign fibroadenomas. MR imaging correctly identified 84% of malignant tumors, 86% of fibroadenomas, and 100% of cysts, and was substantially more accurate in tissue characterization than mammography. The results of ultrasonography were highly similar to those of MR imaging. However, no single modality was infallible, and the three modalities were complementary rather than competitive. Considering the high cost and long examination time of MR imaging, mammography supplemented by ultrasonography seems to be the method of choice in the diagnosis of breast lesions. Nevertheless, MR imaging can add important information when the results of mammography and ultrasonography are insufficient or contradictory.     

Differentiation of phyllodes breast tumors from fibroadenomas on MRI

OBJECTIVE: The purpose of our study was to evaluate the MRI appearance of phyllodes breast tumors and to differentiate them from fibroadenomas. MATERIALS AND METHODS: MR images were obtained on a 1.5-T imager. T1- and T2-weighted sequences and dynamic 2D fast-field echo T1-weighted sequences were performed. MR images of 23 patients with 24 phyllodes breast tumors (one malignant, 23 benign) were analyzed with respect to morphology and contrast enhancement. The tumors were compared with the MRI appearance of 81 fibroadenomas of 75 patients. RESULTS: Well-defined margins were seen in 87.5% of the phyllodes tumors and 70.4% of the fibroadenomas, and a round or lobulated shape in 100% and 90.1%, respectively. A heterogeneous internal structure was observed in 70.8% of phyllodes tumors and in 49.4% of fibroadenomas. Nonenhancing internal septations were found in 45.8% of phyllodes tumors and 27.2% of fibroadenomas. A significantly greater increase in signal was seen on T2-weighted images in the tissue surrounding phyllodes tumors (21%) compared with fibroadenomas (1.2%). Most of both lesions appeared with low signal intensity on T1- and T2-weighted images. After the administration of contrast material, 33.3% of phyllodes tumors and 22.2% of fibroadenomas showed a suspicious signal intensity-time course. CONCLUSION: Phyllodes breast tumors and other fibroadenomas cannot be precisely differentiated on breast MRI. Phyllodes tumors have benign morphologic features and contrast enhancement characteristics suggestive of malignancy in 33% of cases.     

脑肿瘤磁化传递成像和钆剂增强协同作用的研究

目的：研究钆剂（磁显葡胺）和磁化传递（ＭＴ）成像对脑肿瘤增强效果的协同作用。材料和方法：对６０例脑肿瘤行ＳＥＴ１Ｗ和ＰＤＷ，Ｔ２ＷＭＲＩ检查后，继以行钆剂增强后ＳＥＴ１Ｗ和ＭＴＩＳＥＴ１ＷＭＲＩ。然后测定各种脑肿瘤钆剂和ＭＴＩ合用的增强效价。结果：ＭＴＩ能降低脑实质（背景）信号强度，而对肿瘤病灶的信号强度无甚影响，所以钆剂和ＭＴＩ合用的增强效果为不用ＭＴＩ者的２．２４～８倍。能使脑肿瘤病灶增强范围和突出程度有所增加，并显示更多的病灶。ＭＴＩ和半量（０．０５ｍｍｏｌ／ｋｇ）钆剂合用其增强效果相当于双倍剂量钆剂者。结论：ＭＴＩ和钆剂增强对脑肿瘤具有协同增强效果，故可用作脑肿瘤增强ＭＲＩ检查的常规方法。     

MR imaging of hepatic metastases caused by neuroendocrine tumors: comparing four techniques

OBJECTIVE: The aim of our prospective study was to assess the MR imaging characteristics of hepatic metastases of neuroendocrine tumors and to determine the optimal MR sequence for their detection. SUBJECTS AND METHODS: Thirty-seven consecutive patients with liver metastases from neuroendocrine tumors underwent 1.5-T MR imaging of the liver comprising T2-weighted fast spin-echo with respiratory monitoring, breath-hold T2-weighted single-shot fast spin-echo, and T1-weighted gradient-recalled echo sequences before and after the injection of gadoterate dimeglumine. Images were reviewed independently by three observers for the number, location, and pattern of signal and enhancement of metastases. RESULTS: A total of 359 metastases were detected, 279 on T2-weighed fast spin-echo, 231 on T2-weighed single-shot fast spin-echo, 272 on unenhanced T1-weighted, 322 on hepatic arterial phase, and 228 on portal venous phase images. Hepatic arterial phase images revealed the greatest number of metastases in 70% of patients, including 35 metastases seen only on this sequence, and was significantly superior to the unenhanced T1-weighted and portal venous phase sequences (p < 0.01). The lesion-to-liver contrast was significantly greatest with T2-weighed fast spin-echo sequences. The enhancement patterns of metastases were predominantly hypervascular, hypovascular, peripheral with progressive fill-in, and delayed in, respectively, 27, four, four, and two patients. Most metastases with peripheral enhancement and progressive fill-in were heterogeneous on T2-weighted images and were without globular peripheral enhancement. CONCLUSION: Hepatic metastases of neuroendocrine tumors had a typical hypervascular pattern in 73% of patients. Hepatic arterial phase and fast spin-echo T2-weighed sequences are the most sensitive.     

High-resolution magnetic resonance imaging of squamous cell carcinoma of the tongue: an in vitro study

OBJECTIVES: To determine in vitro the potential of high-resolution MRI for evaluating the depth of tumor invasion of the tongue. METHODS: Twenty-one resected specimens of squamous cell carcinoma of the tongue were examined on a 1.5T MRI system with a 4 cm surface coil using four different sequences; T1W SE, T2W SE, 3D-FISP and 3D-CISS. The thickness of normal epithelium, tumor depth and width were measured on both MR images and histopathological sections. RESULTS: The mucosal epithelium, lamina propria and muscles of the tongue were clearly identifiable on MRI. All 21 carcinomas, including three early invasive carcinomas, were clearly demonstrated. A high correlation was found between the values measured by MRI and histopathology for thickness of mucosal epithelium and both depth and width of tumors. There was a good agreement between the T2W SE and the other imaging sequences for measurements of both depth and width of tumors. CONCLUSION: High-resolution MR imaging appears reliable for the in vitro evaluation of depth of tumor invasion in carcinoma of the tongue.     

Breast carcinomas with strong high-signal intensity on T2-weighted MR images: pathological characteristics and differential diagnosis

PURPOSE: To investigate the histopathological characteristics of breast carcinomas with strong high-signal intensity (SHi) on T2-weighted (T2W) MR images (T2-SHi), and discuss the differential diagnosis between T2-SHi breast carcinomas and T2-SHi fibroadenomas. MATERIALS AND METHODS: Thirty of 480 breast carcinomas examined by MRI were defined as tumors with T2-SHi (defined as homogeneous higher signal intensity (SI) compared to surrounding normal breast tissue on fat-suppressed T2W imaging (T2WI). They included eight mucinous and 22 nonmucinous carcinomas. The histopathological characteristics of T2-SHi breast carcinomas, their signal-to-noise ratios (SNRs) on T2WI, contrast-enhancement patterns, and morphology were compared with those of 22 non-T2-SHi breast carcinomas and 19 T2-SHi fibroadenomas. RESULTS: In nonmucinous carcinomas T2-SHi was attributable to a mixture of background matrix, a higher proportion of cells than stroma, abundant cytoplasm, edematous stroma, and hemorrhage. The significantly high SNR (mean = 75) and enhancing internal septations seen in mucinous carcinomas, and the washout phenomenon, irregular border, absence of internal septation, and rim enhancement seen in nonmucinous carcinomas provide useful information for differentiating these tumors from T2-SHi fibroadenomas. CONCLUSION: A mixture of several histopathological characteristics was associated with T2-SHi breast carcinomas. The combined information from T2WI and contrast-enhanced (CE) imaging may help distinguish T2-SHi breast carcinomas from T2-SHi fibroadenomas.     

Cardiac tumors: assessment with Gd-DTPA enhanced MR imaging

Previous studies have shown the value of MR imaging for the identification of cardiac masses. The distinction of intramural tumors from normal myocardium may be equivocal because of the similarity of signal intensity between tumor and normal myocardium on ECG-gated SE images. The purpose of this study was to assess the role of Gd-DTPA for improving the contrast between cardiac tumors and myocardium. Four patients with established or suspected cardiac tumors were imaged with a 1.5 T imager. The T1-weighted images (TR = RR interval, TE = 20-30 ms) were obtained before and immediately after the intravenous injection of Gd-DTPA, at a dosage of 0.1 mmol/kg. Tumors were identified in three patients. All tumors were isointense to the myocardium in precontrast images but demonstrated differential enhancement relative to myocardium after the administration of Gd-DTPA. Two tumors were hyperintense relative to myocardium, and the third was mostly hypointense, surrounded by a hyperintense rim. In the remaining case, no tumor was found and the myocardium was homogeneously enhanced on postgadolinium images. Gadolinium DTPA can produce differential enhancement of tumor from normal myocardium and therefore demonstrate intramural masses.     

MR imaging of acute cerebral infarction: experimental study with Gd-DTPA

To evaluate the sensitivity of MR imaging for acute cerebral infarction and the effectiveness of MR enhancement with Gd-DTPA, we created a canine model of cerebral infarction by transarterial embolization (TAE). The external and internal carotid arteries were embolized respectively through a transfemoral catheter. MR imaging was performed with the Yokogawa Medical System prototype superconducting MR machine "Resona" operating at 0.35 Tesla. MR enhancement was done with 0.4 mmol/kg of Gd-DTPA. Early detectability without Gd-DTPA was 60% (3/5) two hours after TAE and 67% (4/6) at three hours. MR imaging showed high-intensity lesions on the T2-weighted sequence (SE 2000/100). The T1-weighted sequence (SR 250-600/25-35) did not reveal any lesions four hours after TAE. Five animals which received Gd-DTPA showed abnormal enhancement in the brain parenchyma within 30 min after Gd injection on the T1 weighted sequence. Gd-DTPA enhancement not only improved early sensitivity for acute cerebral infarction when MR imaging without Gd-DTPA was negative, but also enhanced the size and number of lesions compared with SE 2000/100 images without enhancement. The breakdown of the blood-brain barrier was suggested to be an important factor in Gd-DTPA enhancement.     

MR of enchondroma and chondrosarcoma: rings and arcs of Gd-DTPA enhancement

MR studies of five chondrosarcomas and three enchondromas were performed with intravenous Gd-DTPA administration. All tumors showed enhancement of scalloped margins and curvilinear septa (ring-and-arc pattern) on T1-weighted SE sequences with Gd-DTPA. On radiologic-pathologic correlation, the enhanced areas corresponded to fibrovascular bundles surrounding hyaline cartilage lobules. The rings and arcs of enhancement with Gd-DTPA on MR is a reflection of the lobulated growth pattern of cartilaginous tumors and therefore helpful in differential diagnosis of bone tumors.     

The contribution of gadolinium to the magnetic resonance diagnosis of spondylodiscitis]

To determine the contribution of Gd-DTPA to the evaluation of vertebral infections 16 MR examinations with i.v. Gd-DTPA injection were performed on 12 patients with diagnosis of spondylodiscitis. All patients were examined with both SE T1- and SE T2-weighted sequences. The SE T1-weighted sequence was repeated following i.v. Gd-DTPA injection (0.1 nmol/kg). Signal intensities and visibility of the lesions were evaluated with MR. For each lesion the grade of visibility on SE T1-weighted sequence was compared with the grade of visibility on SE T2-weighted sequence. Moreover, for each study the information obtained by the combined evaluation of SE T1-weighted sequence without and with Gd-DTPA was compared with the information obtained by combined SE T1- and SE T2-weighted sequences. Gd-DTPA was useful in the evaluation of lesions of the discal space, showing in all cases an area of low signal intensity with peripheral enhancement; this finding allowed, in some cases, to differentiate mild spondylodiscitis from degenerative features. Gd-DTPA was also very useful in determining the extent of the disease: in comparison with MR study without contrast media, the combined evaluation of SE T1-weighted sequence without and with Gd-DTPA better showed the extent of the disease in 7/8 cases (88%).     

Renal cell cancer: Incidence of hemorrhage on MR images in patients with chronic renal insufficiency

This study describes the occurrence of hemorrhage in renal cancer in patients with chronic renal insufficiency as shown on MR images. Thirteen consecutive patients with chronic renal insufficiency who had his tologically proven renal cancer and underwent MRI at 1.5 T were entered in the study. MR examinations included spoiled gradient echo (SGE) and T1-weighted fat-suppressed imaging pre- and postgadolinium administration. All renal cancers were well shown on MR images and were most clearly depicted on postgadolinium T1-weighted fat-suppressed images. Tumors in 12 of 13 patients had regions of high signal intensity on precontrast T1-weighted images. Histology demonstrated intratumoral hemorrhage in all 12 of these patients. Four hemorrhagic tumors were largely cystic on imaging studies. One of these cancers altered in appearance from largely cystic with extensive hemorrhage to largely solid with substantial enhancement after a 2.5-year interval. Renal cancers demonstrated minimal enhancement (11 patients) on early postgadolinium images and were minimally enhanced on delayed images in 10 of 13 tumors. Two renal cancers demonstrated intense enhancement. Renal cancers are well shown on MR images in patients with chronic renal insufficiency. Because of the common occurrence of hemorrhage into renal cancers in patients with renal insufficiency, caution should be exercised when evaluating hemorrhagic cystic lesions in these patients.     

Magnetic resonance imaging of acoustic neuromas: the role of gadolinium-DTPA

Magnetic resonance imaging (MRI) was performed in 20 patients with evidence on computed tomography (CT) of 21 acoustic neuromas before and after intravenous administration (0.1-0.2 mmol/kg body weight) of gadolinium-diethylene-triamine-pentaacetic acid (Gd-DTPA). Multi-section spin-echo (SE) sequences of varying repetition (TR) and echo (TE) times were performed in the transverse and coronal planes with a section thickness of 10 mm. All acoustic neuromas displayed marked enhancement on the T1-weighted (short TR/TE) SE sequence post-Gd-DTPA. The intrameatal component was particularly well demonstrated compared with non-enhanced magnetic resonance (MR) images and contrast-enhanced CT. Identification of intrameatal tumour was difficult on T2-weighted SE images and one tumour was not identified on the T1-weighted SE sequence prior to Gd-DTPA. Four of five intrameatal tumours measuring less than 8 mm could only be demonstrated on CT by using CT air meatography. Extrameatal tumour extension was demonstrated on contrast-enhanced CT, although the assessment of brain-stem involvement and displacement was not as clearly seen as on coronal MR images. In two patients with large acoustic neuromas and a cyst, the true relationship of the cyst to the tumour could only be identified on the post-Gd-DTPA scan. Magnetic resonance imaging with gadolinium-DTPA is a relatively quick, safe, well tolerated and effective method for the diagnosis of acoustic neuroma.     

Comparison of Gd-DTPA-induced signal enhancements in rat brain C6 glioma among different pulse sequences in 3-Tesla magnetic resonance imaging

Background: T1-shortening contrast media are routinely used in magnetic resonance (MR) examinations for the diagnosis of brain tumors. Although some studies show a benefit of 3 Tesla (T) compared to 1.5T in delineation of brain tumors using contrast media, it is unclear which pulse sequences are optimal.

Purpose: To compare gadopentetate dimeglumine (Gd-DTPA)-induced signal enhancements in rat brain C6 glioma in the thalamus region among different pulse sequences in 3T MR imaging.

Material and Methods: Five rats with a surgically implanted C6 glioma in their thalamus were examined. T1-weighted brain images of the five rats were acquired before and after Gd-DTPA administration (0.1 mmol/kg) using three clinically available pulse sequences (spin echo [SE], fast SE [FSE], fast spoiled gradient echo [FSPGR]) at 3T. Signal enhancement in the glioma (E_T) was calculated as the signal intensity after Gd-DTPA administration scaled by that before administration. Pulse sequences were compared using the Tukey-Kramer test.

Results: E_T was 1.12±0.05 for FSE, 1.26±0.11 for FSPGR, and 1.20±0.11 for SE. FSPGR showed significantly higher signal enhancement than FSE and comparable enhancement to SE.

Conclusion: FSPGR is superior to FSE and comparable to SE in its ability to delineate rat brain C6 glioma in the thalamus region.     

Magnetic resonance evaluation of the presence of an extensive intraductal component in breast cancer

PURPOSE: To determine whether the presence of extensive intraductal components (EIC) in breast carcinomas can be accurately evaluated on magnetic resonance (MR) images. MATERIAL AND METHODS: Ninety-three women with breast cancer, aged between 32 and 79 years (mean 54 years), underwent three-dimensional dynamic MR imaging (dyMRI) with fat suppression and magnetization transfer contrast before breast-conserving surgery. The tumors were classified on dyMRI as circumscribed, microlobulated, and/or speculated, and their size was measured. Spotty or linear continuous enhancement (SLE) from the main tumor to the nipple and segmental enhancement surrounding the main tumor (SE) were considered indicative of intraductal tumor spread. The correlation between preoperative MRI and macroscopic and microscopic findings was examined. RESULTS: On MR images, the tumor sizes ranged from 0.8 to 3.4 cm. These measurements coincided with histologic measurements in circumscribed tumors. However, in tumors with microlobulated or spiculated borders, tumor size tended to be underestimated on MR images. Of 93 patients, 59 (63.4%) had histologically confirmed EIC; 42 of the 59 cancers (71.2%) manifested SLE or SE on MR images. The sensitivity, specificity, and accuracy of MR imaging in detecting EIC were 71%, 85%, and 76%, respectively. CONCLUSION: MR imaging facilitates the detection of EIC in breast masses. This information is valuable for the planning of breast-conserving surgery.     

Enhancement effects and relaxivities of gadolinium-DTPA at 1.5 versus 3 Tesla: a phantom study.

PURPOse: To investigate the difference in enhancement effects and relaxivities of the gadolinium chelate at 1.5 and 3 Tesla (T) and to elucidate the contribution of the high magnetic field to contrast enhancement in spin-echo (SE) and gradient-echo (GRE) images. METHODS: Phantoms containing water with or without gadopentetate dimeglumine (Gd-DTPA) at different concentrations were scanned using 1.5T and 3T MRI scanners of the same manufacturer and under the same temperature conditions and scanning parameters. Relaxivities of gadolinium, R1 and R2, were estimated from serial T1 and T2 values of the phantoms using linear regression. Contrast enhancement ratios in SE and GRE T1-weighted images were compared at 1.5 and 3T. RESULTS: The R1 and R2 of Gd-DTPA at 1.5 and 3T were 4.79 and 5.14, and 4.50 and 5.09, respectively. Although the relaxivities at 3T were slightly lower than those at 1.5T, the contrast enhancement ratio improved in both SE and GRE images as a result of T1 prolongation of the water at 3T. CONCLUSION: The decrease in relaxivities of the Gd-DTPA at 3T appears to be so small that T1 prolongation of the water improves contrast enhancement, suggesting a potential clinical advantage in administration of Gd-DTPA at high field strength.     

Gd-DTPA in clinical MR of the brain: 1. Intraaxial lesions

Over 35 intraaxial lesions in 15 patients suspected of having intracranial tumors were studied with MR before and after injection of Gadolinium-DTPA (Gd-DTPA). Diseases included primary and metastatic brain tumors, plaques of multiple sclerosis, occult arteriovenous malformations, lymphoma, toxoplasmosis, and pituitary adenoma. The precontrast T2-weighted sequence (SE 2000/30, 60) was found to be most sensitive in detecting intraaxial lesions, showing 17 lesions that were not seen on the post-Gd-DTPA T1-weighted sequence (SE 500/30). In one case of multiple sclerosis, several lesions seen on the pre-Gd-DTPA study on T2-weighted images faded after injection of Gd-DTPA (due to T2 shortening). In two patients with large metastatic foci, other small metastatic lesions were seen better after Gd-DTPA on both T1- and T2-weighted sequences. Four other patients with only one focal-enhancing lesion and one patient with multifocal lesions on T1-weighted images actually had a much larger single glioma depicted on pre-Gd-DTPA T2-weighted images. In a patient with AIDS, a ring-enhancing lesion thought to be an abscess proved to be lymphoma. The cryptic arteriovenous malformations enhanced but showed more characteristic findings, such as hemorrhage, on pre-Gd-DTPA studies. Our experience suggests that Gd-DTPA may not improve sensitivity of MR in the detection of intraaxial lesions. However, functional aspects of brain disease, such as the presence of perfusion of a lesion and active breach of the blood-brain barrier, are depicted well with Gd-DTPA and are vital for proper diagnosis in many instances.     

Magnetic resonance (MR) imaging of chordoma and chondroma in the skull base--differential diagnosis by IR sequence]

Differential diagnosis of chordoma and chondroma in the skull base is sometimes difficult. We retrospectively reviewed the MR images of 14 patients with skull base tumors (nine chordomas, four chondromas and one chondrosarcoma). MR imaging was performed with a 0.5 Tesla system (Picker International). Inversion recovery (IR) (2500-2100/600-500/40), T1-weighted spin echo (SE) (800-600/40), and T2-weighted SE (2500-1800/120) images were obtained. On IR images, seven of eight chordomas showed heterogeneous low signal intensity, and one chordoma and all chondromas showed markedly low signal intensity similar to that of CSF. Calcified or ossified portions of the chondromas were demonstrated as areas of moderately low intensity on IR images. Chondrosarcoma showed moderately low intensity similar to that of chordoma. T1-weighted SE images of chordoma and chondroma showed no difference in signal intensity. On T2-weighed SE images, six of nine chordomas and all chondromas showed markedly high signal intensity. Three chordomas and one chondrosarcoma showed moderately high signal intensity. In the diagnosis of skull base tumors, the IR sequence seems to be useful for differentiating chondroma from chordoma.     

Do T2-weighted pulse sequences help with the differential diagnosis of enhancing lesions in dynamic breast MRI?

In this study, our purpose was to determine whether T2-weighted images are a useful diagnostic adjunct for lesion characterization in dynamic breast MRI. On a 1.5-T system, 205 enhancing benign and malignant breast tumors were examined. The standardized protocol consisted of a T2-weighted turbo spin echo (TSE) pulse sequence with and without spectral fat suppression (SPIR), followed by a two-dimensional dynamic series with subtraction postprocessing. In 59 cases, T2*-weighted gradient-echo images also were obtained. Two independent radiologists visually rated the lesions (101 malignant, 104 benign) as having either a low or a high signal with respect to the adjacent glandular tissue. To assess age dependency of lesion enhancement velocities and T2-TSE signal intensities, we compared the results for patients at or below the age of 50 (group A), between 40 and 50 (group B), and beyond the age of 50 (group C). In T2-weighted TSE images, breast cancers were iso- or hypointense with respect to breast parenchyma in 87% of cases, whereas fibroadenomas were hyperintense in 71%. Visual assessment of lesion appearance in T2-weighted TSE images allowed to distinguish between fibroadenomas and breast cancers, with a respective sensitivity, specificity, positive predictive value, and negative predictive value of 72%, 75%, 46%, and 90% for young patients; 94%, 66%, 78%, and 89% for the patients between 40 and 50; and 89%, 62%, 85%, and 68% for the patients over 50 years of age. No significant difference was found for the distribution of signal intensities of lesions in T2*-weighted images or in fat-suppressed images. In a contrast-enhancing breast lesion, careful analysis of T2-weighted TSE images can improve differential diagnosis. The accuracy of this criterion varies with age.     

SPIO与Gd-DTPA联合增强检测大鼠肝癌病灶的实验研究

目的 :观察联合使用SPIO和Gd DTPA对大鼠肝癌模型的增强特点。材料和方法 :制作 3 0只大鼠肝癌模型 ,增强前后行MR扫描 ,平扫序列包括SE、TSE、GRE的T1、T2WI序列。增强扫描分为 4组 ,其中Gd +SPIO联合增强组 10只 ,先注射Gd DTPA ,行SE、GRET1WI扫描 ,随后给予SPIO造影剂 ,扫描序列同平扫 ;SPIO +Gd联合增强组 10只 ,先注射SPIO ,行SE、GRET1WI扫描 ,12min后再给予Gd DTPA ,扫描序列同平扫 ;Gd、SPIO增强组各为 5只 ,增强扫描序列同平扫。分析各增强扫描组中病灶的增强特点。结果 :两种联合增强方法中 ,肝脏信号强度在所有扫描序列中均较平扫时下降 ,但与SPIO增强组无差异 ;病灶的SNR、CNR在SE、GRET1WI中明显高于平扫和SPIO、Gd DTPA增强法 ;在T2WI中病灶的SNR、CNR和单独使用SPIO无显著性差异。两种联合增强方法之间的SNR和CNR在每种扫描序列中没有显著性差异。结论 :SPIO和Gd DTPA联合增强方法利用了两种造影剂的优势 ,增加了肿瘤病变的对比 ,可提高发现病变的几率。     

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.