Endorectal surface coil MR imaging of prostatic carcinoma with the inversion-recovery sequence

The value of inversion-recovery (IR) sequences in the diagnosis and staging of prostatic carcinoma with magnetic resonance (MR) imaging was studied. Twenty-six patients with carcinoma of the prostate were imaged at 1.5 T with an endorectal surface coil and with a variety of IR sequences and a set of spin-echo (SE) sequences for comparison. Ex vivo prostate specimens were imaged again at the same field strength. The two images were correlated with histologic sections. Cancer was identified with MR imaging in 96% of patients. Of the tumors more than 4 mm in diameter, 87% were identified on T2-weighted SE images, whereas only 26% were identified on IR images. However, IR images may be more useful in local staging of carcinoma. Gross capsular infiltration was present in only two patients; however, it was detectable (and excluded in five other patients) by means of IR images. It was not detectable on SE images. The high quality of images obtained with the endorectal coil was confirmed. The authors conclude that addition of the IR sequence to MR imaging with the endorectal coil may improve the usefulness of this examination.     

Mucinous carcinomas involving the prostate: atypical findings at MR imaging.

The magnetic resonance (MR) imaging findings in four patients with mucinous tumors involving the prostate are presented. The MR appearance of these tumors differed from that of typical prostatic adenocarcinomas in that the signal intensity on T2-weighted images approximated or exceeded that of the uninvolved peripheral zone. The unusual appearance of mucinous prostate tumors may present problems in diagnosis and staging with MR imaging.     

Prostate and seminal vesicles after irradiation: MR appearance.

Familiarity with the morphologic changes in the prostate and seminal vesicles (SV) after pelvic irradiation is important to the correct interpretation of follow-up magnetic resonance (MR) studies. A retrospective study of 38 patients with prostatic or other pelvic tumors treated with radiation showed that 31.6% had a normal prostatic zonal pattern (peripheral zone hyperintense to central gland) on T2-weighted images, and 7.9% showed reversal of the zonal pattern; among the rest, the entire gland was diffusely isointense to fat in 42.1%, hypointense to fat in 10.5%, and hyperintense to fat in 7.9%. Sixty-three percent of the SV had a normal appearance, 21% had fewer tubules but normal signal intensity (SI), 8% had diffuse loss of SI (hypointense to fat), and 8% were hypointense to muscle. Quantitative measurements of SI of the prostate and SV demonstrated a statistically significant lower mean value for the irradiated patients relative to 10 control patients. A decrease in the size of both the prostate and SV was observed in 33% of patients with baseline studies. Use of additional treatment modalities in patients with prostatic carcinoma appeared to correlate with increased likelihood of developing abnormal changes. The authors conclude that in the irradiated patient, the prostate and SV can develop several patterns of SI abnormalities; in particular, diffuse low SI in the prostate and SV should establish radiation fibrosis as an important differential diagnosis to consider.     

MR imaging of the pericardial cyst.

Findings obtained with magnetic resonance (MR) imaging in four patients with pericardial cyst are reported. MR imaging allowed not only localization and diagnosis in all four cases but characterization of cystic content. MR imaging, including RARE (rapid acquisition with relaxation enhancement) MR hydrography, which shows only liquids with T2s greater than 500 msec, proved to be useful in characterizing the fluid content of a mediastinal lesion and monitoring follow-up. In one case, MR imaging allowed differentiation of a pericardial cyst from a suspected necrotic lymph node in a patient with colic carcinoma, with subsequent correction of staging and therapy. The authors conclude that MR imaging is the method of choice for diagnosis (especially in unusual locations) and monitoring of pericardial cysts and for differential diagnosis of malignant mediastinal cystic tumors that show a solid part.     

Intracavitary birdcage resonator: Applications to the human prostate

Twenty-five patients with prostatic cancer were pro- spectively examined with a prototype endorectal surface coil featuring a birdcage resonator circuit design. The purpose was to determine the safety of an intracavitary probe for magnetic resonance (MR) imaging of the pelvis that incorporates the “inside-out” characteristics of a volume coil design and allows high-resolution MR imaging of the prostate and potentially serves as an alternative to single-loop intracavitary surface coils. Clinically useful images supplementing images obtained with the body or external surface coils were obtained with the prototype probe. It was tolerated by all patients enrolled in the study, and none experienced side effects. The cylindrically symmetric sensitivity profile of the probe allowed identification of prostate tumors and pelvic lymph node and bone me-tastases. Volume-type coils may improve endopelvic MR imaging when used alone or in combination with external coil systems.     

MR imaging detection of calcified intracranial lesions and differentiation from iron-laden lesions.

Magnetic susceptibility variation caused by calcium permits limited detection of intracranial calcifications and/or their distinction from iron-laden lesions with spin-echo or gradient-echo magnetic resonance (MR) techniques. The magnetic susceptibility sensitivity of phase imaging has been used to detect iron-laden lesions. A new approach that combines the magnetic susceptibility sensitivity of both gradient-echo and phase imaging to yield greater imaging sensitivity to calcium is presented. Two-dimensional fast low-angle shot (FLASH) gradient-echo imaging with phase image reconstruction (gradient-echo phase [GEP]) was used at 1.0 and 1.5 T. Twelve patients with computed tomography-proved calcified intracranial lesions (greater than or equal to 200 HU) and seven patients with iron-laden intracranial lesions having a characteristic appearance on T1- and T2-weighted and FLASH MR images were studied. The GEP imaging technique helped detect calcified intracranial lesions (greater than or equal to 200 HU) and helped distinguish them from iron-laden lesions.     

MR灌注成像在前列腺疾病诊断中作用的初步探讨

目的探讨MR灌注成像在前列腺良恶性病变中的初步应用,评价血管内皮生长因子(VEGF)和微血管密度(MVD)与MR灌注成像各指标的关系。方法对临床诊断为前列腺疾病的70例患者,其中良性前列腺增生(BPH)42例,前列腺癌(PCa)28例,进行MR灌注成像,并对标本进行免疫组织化学检测;分析病变的灌注曲线最大线性斜率(SSmax)、T2*弛豫率(△R2* peak)与免疫组织化学检查结果(VEGF、MVD)的相关性。结果(1)BPH组增生结节灌注曲线的SSmax及△R2*peak分别为:33．5±3．1、1．5±0．1;PCa组癌灶灌注曲线的SSmax及△R2*peak分别为:58．4±4．7、3．1±0．5,两者之间差异有统计学意义(t值分别为2．13、2．29,P值均<0．05);PCa组高、中、低分化腺癌的SSmax分别为:52．3±3．4、56．4±4．3、60．7±5．2,差异有统计学意义(F=132．04,P< 0．05),△R2*peak分别为:2．9±0．4、3．1±0．5、3．2±0．7,差异有统计学意义(F=114．82,P<0．05)。(2)BPH组VEGF阳性9例,MVD值为22．76±6．54;PCa组VEGF阳性为24例,MVD值为71．38±9．17;PCa的VEGF和MVD的表达水平明显高于BPH患者(X2=27．86,P<0．01;t=20．4,P< 0．01),PCa、BPH的VEGF表达与MVD表达呈正相关性(P<0．01);灌注加权成像(PWI)参数SSmax、△R2*peak与VEGF、MVD具有相关性(P<0．01)。结论PWI的有关指标(SSmax、△R2*peak)与MVD和VEGF的表达水平相关,有可能为前列腺疾病良恶性的鉴别提供信息。     

Comparison of MR imaging after barium administration with CT in pelvic disease.

The use of magnetic resonance (MR) imaging for evaluating the abdomen and pelvis has been limited by the lack of a suitable contrast agent. The purpose of this study was to compare axial MR imaging after rectal barium administration with computed tomography (CT) for delineation of normal anatomy and lesions of the pelvis. MR images and CT scans of 11 patients were studied retrospectively and independently by four radiologists. No substantial differences in the visualization of normal bowel, iliac vessels, lymph nodes, bladder, prostate, seminal vesicles, uterus, and cervix and in detection of abnormalities were seen between CT scans and axial MR images obtained after barium administration. This preliminary study suggests that axial MR imaging with rectal barium is a useful alternative to CT in evaluating pelvic disease.     

MR imaging characteristics of hepatic tumors

There is no doubt that radiologists play an increasingly important role in the detection of focal liver lesions, and in the evaluation of persistent or recurrent malignant disease after treatment. The characterization of focal liver lesions depends on the clinical integration of the information generated by different radiologic techniques. Most often, MR imaging is quite effective in liver tumor characterization. Our purpose is to provide an overview of the MR characteristics of the most commonly encountered liver tumors and their differential diagnosis, with the most accepted reliable proof of the lesion type in a clinical environment. Radiologists must know the level of confidence they can reach in a given diagnosis, and the influence that this diagnosis has in the patient's management. With this knowledge, radiologists decide whether to leave or follow-up the lesion, perform tissue samples, or carry out therapeutic procedures. Received 28 September 1995; Revision received 22 April 1996; Accepted 26 April 1996     

Differentiation between hemangiomas and cysts of the liver with nonenhanced MR imaging: Efficacy of T2 values at 1.5 T

The authors studied the utility of non-contrast-agent-enhanced magnetic resonance (MR) imaging for differentiating cysts and cavernous hemangiomas of the liver. Nineteen patients with hemangiomas (51 lesions) and 16 with cysts (30 lesions) were studied with a 1.5-T MR imager. T2 values were calculated with the two-point method to evaluate the efficacy of T2 values in the differentiation between hemangiomas and cysts of the liver. For lesions larger than 1 cm, the mean T2 value of cysts (306 msec ± 156) was significantly longer than that of hemangiomas (113 msec ± 15) (P < .0001); there was no overlap of the ranges for T2 values of hemangiomas and cysts. All cysts larger than 1 cm could be differentiated from hemangiomas by using a threshold T2 value of 140 msec. This study suggests that calculated T2 values permit differentiation between hemangiomas and cysts larger than 1 cm at 1.5 T.     

MR imaging assessment of juxta cortical edema in osteoid osteoma in 28 patients

Osteoid osteoma (OO) is a benign skeletal neoplasm. Twenty-eight patients with proven OO were studied with MRI regarding soft tissue involvement which was diagnosed when high proton-density and T2-weighted signal intensity and low signal intensity on T1-weighted images were found close to bone. Most tumors were located in the femur and tibia; 6 cases diaphyseal, 12 metaphyso-diaphyseal, and 10 epiphyseal. In relation to the cortex, 15 were located centrally or in its outer margin. Soft tissue involvement was found in 15 patients (53.6 %). A statistical relationship was found between soft tissue involvement and the tumor's location with regard to the cortex, being more frequent in peripherally located tumors. Therefore, soft tissue involvement is a frequent finding in peripherally located OO. Received 30 December 1996; Revision received 21 April 1997; Accepted 16 June 1997     

Evaluation of hepatic lesions and hepatic parenchyma using diffusion-weighted echo-planar MR with three values of gradient b-factor

PURPOSE: To determine whether diffusion-weighted echo-planar (EP) MR images with very small, small, and large gradient b-factors are useful in evaluating hepatic lesions and hepatic parenchyma. MATERIALS AND METHODS: Approximate values of the apparent diffusion coefficients for diffusion (D) and for flowing spins (D*) for 96 hepatic lesions (26 hepatocellular carcinomas [HCCs], 28 metastases, 26 hemangiomas, and 16 cysts) and the non-lesion-bearing regions of parenchyma in 78 livers (50 noncirrhotic and 28 cirrhotic) were calculated from EP images (modified for gradient b-factors of 3, 50, and 300 second/mm(2)). RESULTS: Liver cysts and noncirrhotic livers showed statistically higher mean D* values than HCCs, hemangiomas, metastases, and cirrhotic livers (P < 0.05 on Scheffé post hoc analysis). Liver cysts showed statistically higher mean D values than HCCs, metastases, noncirrhotic livers, and cirrhotic livers (P < 0.05). Liver hemangiomas showed statistically higher mean D values than HCCs, noncirrhotic livers, and cirrhotic livers (P < 0.05). CONCLUSION: The D* value in addition to the D value may be useful for evaluating the nature of diffusion and flowing spins in hepatic lesions and hepatic parenchyma.     

Granulomatous prostatitis: a pitfall in MR imaging of prostatic carcinoma

Granulomatous prostatitis is an uncommon disease that can prostatic carcinoma on both digital rectal examination and transrectal ultrasound. Four patients who underwent magnetic resonance imaging of the prostate had a histological diagnosis of graanulomatous prostatitis; three of them had recent urinary tract infections. The other patient had an associated midline prostatic cyst and a focus of malignancy. T1-and T2-weighted spin-echo images were obtained in all cases. Peripheral zone lesions of decreased signal intensity, suggestive of carcinoma,were found in all four patients on T2-weighted images. Granulomatous prostatitis should be considered in the differential diagnosis of low signal intensity areas with prostatic magnetic resonance imaging. Correspondence to; P.A. Gevenois     

MR imaging of disorders of the brachial plexus

The authors evaluated 64 consecutive patients with suspected brachial plexus (BP) abnormalities of diverse cause with magnetic resonance (MR) imaging, using the body coil and a standardized protocol. Of the 43 patients for whom follow-up was available, 25 were suspected of having neoplastic involvement of the BP, nine had sustained injuries, and nine presented with BP symptoms of uncertain cause. MR imaging was 63% sensitive, 100% specific, and 77% accurate in demonstrating the abnormality in this diverse patient population. When patients with neoplastic and traumatic disorders were considered separately, sensitivity increased to 81%, accuracy to 88%, and specificity remained unchanged. In the patients with a clinical diagnosis of idiopathic or viral plexitis, the MR imaging findings were normal, serving to exclude other structural abnormalities. It is concluded that MR imaging is valuable in the assessment of a wide range of BP disorders.     

Detection of prostate cancer: Utility of diffusion-weighted MR imaging and 3D MR spectroscopic imaging

Purpose

To prospectively compare the mean ADC generated from DWI, the mean choline + creatine/citrate ratio generated from 3D MRS and the combined mean ADC and mean choline + creatine/citrate ratio in the detection of prostate cancer, and to correlate between the choline + creatine/citrate ratio and the aggressiveness of malignancy determined by Gleason score, with histopathological examination of the excised gland as the reference standard.

Patients and methods

Forty-six patients with biopsy-proved cancer underwent pre-operative MRI at 1.5 T. Axial T1, axial, coronal and sagittal T2-weighted, diffusion-weighted and 3D MRS using a point-resolved spectroscopic sequence (PRESS) were acquired. The mean ADC, mean choline + creatine/citrate ratio and combined parameters for malignant lesions are correlated with the pathological results. For each malignant lesion choline + creatine/citrate ratio was correlated with the aggressiveness of malignancy determined by Gleason score. Receiver operating characteristic (ROC) curves were used to determine sensitivity, and specificity of the studied parameters, and Kappa measures of agreement were calculated for prostate cancer detection.

Results

The mean ADC for tumor tissue was 1.0 ± 0.22 × 10⁻³ mm²/s (mean ± SD), and was significantly lower than that for non-tumor tissue 1.44 ± 0.28 × 10⁻³ mm²/s (p < 0.001). For MRS study the mean (choline + creatine)/citrate ratio in tumor tissue was 1.98 ± 1.0, and was significantly higher than that for non-tumor tissue, 0.72 ± 0.39 (p < 0.001). By combining both ADC values and (choline + creatine)/citrate ratio for differentiating malignant from non-malignant tissues a receiver operating characteristic analysis (ROC) curve showed Area under curve (AUC = 0.93) and was significantly higher than either (choline + creatine)/citrate ratio alone (AUC = 0.86) (p < 0.001) or ADC value alone (AUC = 0.89) (p < 0.001). There is an increasing (choline + creatine)/citrate ratio with increasing Gleason score, however, there is overlap between groups. A greater sensitivity of MRS for tumor detection 85% and 92% was present for tumors with Gleason score 4 + 3 and ?4 + 4, respectively, while for tumors with Gleason score 3 + 3 the sensitivity was 63%.

Conclusion

The combination of ADC and (choline + creatine)/citrate ratio is better than each parameter alone in differentiating between tumor and non-tumor prostatic tissue, also MR spectroscopic imaging findings of prostate tumor (Cho + Cr)/Cit ratio correlate with pathologic Gleason score. The combined parameters offer a promising non-invasive method for the diagnostic workup of prostate cancer.     

MR imaging of uterine cervical carcinoma: comparison between fast spin-echo MRI and GRASE

The aim of our study was to compare the image quality of T2-weighted gradient-echo-and-spin-echo (GRASE) MRI and fast spin-echo (FSE) MRI for imaging of cervical carcinoma. In 40 patients FSE₈ (TR/TE = 3400/90 ms) MRI with echo train length (ETL) of 8, GRASE (3400/90) MRI with ETL of 18, turbo factor of 6 and 3 gradient reversals, and FSE₁₈ (2500/120) MRI with ETL of 18 were performed. Tissue contrast, subjectively rated image quality, and accuracy of tumor delineation were compared. Surgical correlation was obtained in 27 subjects. Contrast-to-noise ratios of the tumor–cervix stroma, tumor–parametrium and tumor–rectum wall interfaces were better in FSE₁₈ than in FSE₈ and GRASE (P < 0.001) but not different between FSE₈ and GRASE. Subjective image quality was better in FSE₁₈ and FSE₈ than in GRASE (P < 0.02). The accuracy of tumor delineation was similar for the three different sequences. The accuracy of FSE and GRASE MRI for the delineation of cervical carcinoma is similar. Based on measurement of image quality and CNRs, however, high turbo factor FSE provides better image quality in MRI of cervical carcinoma.Whether the superior characteristics may result in better staging has to be explored in larger clinical trials. Received 25 March 1997; Revision received 20 June 1997; Accepted 23 June 1997     

MR imaging of synovial tumors and tumor-like lesions

The clinical diagnosis of synovial tumors and tumorlike lesions is difficult, and radiographic findings may establish a confident diagnosis only in some cases. MR imaging has become the modality of choice in evaluating these lesions, because with it a presumptive diagnosis can be made in most cases. Our goal is to review the MR features of pigmented villonodular synovitis, giant-cell tumor of the tendon sheath, synovial chondromatosis, synovial hemangioma, lipoma arborescens, synovial cysts and synovial sarcoma, emphasizing those findings that suggest a specific diagnosis.     

Muscle edema in musculoskeletal tumors: MR imaging characteristics and clinical significance.

To determine the frequency and clinical significance of tumor-associated muscle edema, magnetic resonance (MR) imaging findings in 46 consecutive patients with benign or malignant musculoskeletal lesions were reviewed. Increased muscle signal intensity on T2-weighted, STIR (short-inversion-time inversion-recovery), and gadopentetate dimeglumine-enhanced T1-weighted images was present in 41 cases, with the clearest delineation of tumor margins seen on T2-weighted images. Typical peri/paratumoral edema (PTE) was present in equal proportions of malignant (25 of 37) and benign lesions (six of nine). Massive edema involving the entirety of at least one contiguous muscle--to the authors' knowledge, a previously undescribed finding--was identified on MR images of eight malignant and two benign lesions (22% of both groups). All cases of massive edema had a substantial soft-tissue component and involved muscles disrupted by tumor at the point of attachment to bone. Malignant tumors associated with massive edema were larger than those with typical or no PTE, showed a poorer response to initial chemotherapy, and had a higher frequency of metastases at diagnosis. Thus, the presence of massive muscle edema appears to be an ominous clinical finding in patients with malignant musculoskeletal lesions.     

扩散加权成像鉴别前列腺癌及良性前列腺增生的价值

目的探讨良性前列腺增生(BPH)和前列腺癌(PCa)的扩散加权成像(DWI)和表观扩散系数(ADC)图表现,及对PCa的鉴别诊断价值。方法分析18例BPH和25例PCa的DWI和ADC图表现,并分别测量癌肿区的ADC值及BPH的外周带(PZ)及中央腺体(CG)的ADC值,比较其间是否存在差异。结果BPH的DWI和ADC图上PZ信号近似均一,CG信号欠均匀。PCa在DWI上呈高信号,ADC图呈低信号,均能直观显示癌灶范围。受侵犯的精囊和骨盆骨转移灶DWI上呈高信号,ADC图呈低信号。PCa的ADC值[(0．49±0．09)×10-3mm2／s]与BPH的PZ及CG的ADC值[(1．27±0．14)×10-3mm2／s、(0．96±0．14)×10-3mm2／s]比较,差异均有统计学意义(t值分别为-52．46、-31．49,P值均<0．01),PCa的ADC值与BPH的PZ无重叠,与CG也仅有少量重叠(1／127,0．7％)。结论DWI和ADC图可显示PCa位置、范围及周围侵犯、转移情况;根据DWI和ADC图上病变的信号特点及ADC值可以鉴别BPH和PCa。     

3D 1 HMRSI对外周带前列腺癌鉴别诊断价值的初步研究

目的:探讨3D1HMRSI(three dimensional proton MR spectroscopic imaging)研究外周带前列腺癌(PCa)的代谢特点,及对外周带PCa的鉴别诊断价值。方法:分析18例良性前列腺增生(BPH)和21例PCa的3D MRSI表现。测量外周带PCa体素及BPH外周带体素的(Cho Cre)/Cit及Cho/Cre,并比较它们之间的差异。结果:BPH的外周带波谱主要表现为Cit高耸,Cho次之,Cre最低;PCa波谱主要表现为Cit峰明显下降甚至消失,Cho显著升高,两者波峰可呈现倒置,(Cho Cre)/Cit>0.86。PCa体素的(Cho Cre)/Cit显著高于BPH体素,且两者仅存在小部分重叠,PCa体素的Cho/Cre也显著高于BPH体素,但两者存在较大部分重叠;经ROC曲线分析得出(Cho Cre)/Cit对外周带PCa的鉴别诊断效能高于Cho/Cre,(Cho Cre)/Cit对外周带PCa的最佳诊断阈值为1.16。结论:外周带PCa的3D MRSI表现具有特征性,(Cho Cre)/Cit为诊断外周带PCa的有效指标,以(Cho Cre)/Cit>1.16作为诊断标准,可获得较高的敏感度、特异度和准确度(分别为99.3%、99.2%、99.3%)。