Prostatic pathology imaged by magnetic resonance. 58 cases

Forty-eight patients with prostatic disease (benign prostatic hyperplasia (B.P.H.), carcinoma, cysts, myoma and prostatitis) and 10 normal volunteers underwent magnetic resonance imaging (M.R.I.) of the prostate. The prostatic parenchyma was best evaluated by a T2-weighted spin-echo pulse sequence. The prostate in patients with B.P.H. often had a homogeneous or more rarely a nodular appearance on T2-weighted images. In most cases, a peripheral dark rim is observed. All prostate in patients with carcinoma had an heterogeneous appearance on T2-weighted images. While most of the prostatic carcinomas appeared hypo-intense relative to adjacent prostatic parenchyma, some of the neoplasms had a high or mixed-high and low signal. The myoma showed a low-signal nodule like carcinoma. The cyst appears as a liquid tumor. The prostatitis had an homogeneous bright signal. With the used methodology, MRI can differentiate prostatic diseases in many cases. Nevertheless the technique has to be optimized to improve its accuracy.     

Prostatic carcinoma and benign prostatic hyperplasia: inability of MR imaging to distinguish between the two diseases

Forty patients with prostatic carcinoma or benign prostatic hyperplasia (BPH) underwent magnetic resonance (MR) imaging of the prostate. In vitro MR images of six prostate specimens were also obtained. The prostatic parenchyma was best evaluated by a T2-weighted spin-echo pulse sequence. The prostate both in patients with prostatic carcinoma and patients with BPH often had an inhomogeneous and nodular appearance on T2-weighted images. While most of the prostatic carcinomas appeared hyperintense relative to muscle and adjacent prostatic parenchyma, some of the hyperplastic nodules had a signal intensity similar to carcinoma. With current imaging techniques, MR imaging cannot differentiate prostatic carcinoma from BPH with certainty.     

Gadolinium-DOTA enhanced MR imaging of prostatic lesions. Preliminary results on 14 cases.

Fourteen patients with prostatic carcinoma, benign prostatic hyperplasia, or chronic granulomatous prostatitis underwent gadolinium-DOTA enhanced magnetic resonance imaging of the prostate. Gadolinium-DOTA was administered intravenously in a dosage of 0.1 mmol/kg body weight. All studies were performed on a superconductive 1.5-T system. As compared to noncontrast T1- and T2-weighted images, Gd-DOTA enhanced T1-weighted images were useful in distinguishing malignant tumor from granulomatous prostatitis in one case, but were uncontributive to the differentiation between carcinoma and benign prostatic hyperplasia.     

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.     

Seminal vesicles: biopsy-related hemorrhage simulating tumor invasion at endorectal MR imaging.

The diagnosis of seminal vesicle invasion by prostatic carcinoma is based on observation of foci of relatively decreased signal intensity on T2-weighted magnetic resonance (MR) images. Similar findings were observed in the absence of tumor invasion in nine patients who had recently undergone prostatic needle biopsy. Noncorresponding foci of abnormally increased signal intensity were also present on T1-weighted images in eight patients. These signal intensity abnormalities were of variable location and extent, and usually did not follow the expected pattern of spread from the primary prostatic tumor site. Radical prostatectomy in all patients showed the seminal vesicles to be normal. Signal intensity patterns observed on MR images appear to represent hemorrhagic breakdown products related to prostatic needle biopsy, which may result in direct trauma to the seminal vesicles. Another potential mechanism is retrograde transport of blood products from the site of prostatic biopsy to the seminal vesicles via the ejaculatory ducts. Awareness of this phenomenon will assist in accurate interpretation of MR images for staging of prostate cancer.     

Small hepatocellular carcinoma treated with percutaneous ethanol injection: MR imaging findings.

Fifty-seven magnetic resonance (MR) imaging examinations were obtained at 0.5 T in 19 patients before and after percutaneous ethanol injection (PEI) for 23 hepatocellular carcinoma (HCC) lesions less than 3.5 cm in diameter. Seventeen patients also underwent MR imaging 6 months after completion of therapy. In 11 patients, computed tomography was performed before and after treatment. After PEI, fine-needle biopsy specimens were obtained in all cases. Before treatment, HCC lesions had low signal intensity on T1-weighted images in 13 cases, had the same signal intensity as normal liver parenchyma in six, and had high signal intensity in four; all 23 tumors had high signal intensity on T2-weighted images. After treatment and at 6-month follow-up, all 21 lesions that contained no malignant cells at fine-needle biopsy had high signal intensity on T1-weighted images and had low signal intensity on T2-weighted images. The remaining two HCC lesions in which tumor necrosis was not achieved with PEI displayed a different MR pattern, since the residual neoplastic tissue showed no change in signal intensity on either T1- or T2-weighted images. The authors conclude that MR imaging may be useful for evaluating the effectiveness of PEI in achieving tumor regression.     

Magnetic resonance imaging of the prostate

The prostate was examined by magnetic resonance imaging (MRI) in 33 subjects, including five normal volunteers, 18 with prostatic carcinomas, seven with benign nodular hyperplasias, two cases of acute prostatitis, and one case of chronic prostatitis. Of 18 prostatic carcinomas, 16 produced an inhomogeneous signal intensity, with areas of diminished signal on T1-weighted scans and usually increased signal on T2-weighted images relative to the rest of the prostate. However, a similar appearance was also seen in five cases of benign nodular hyperplasia. It is doubtful at present whether MRI is able to reliably differentiate benign from malignant prostatic disease. Extraprostatic tumor extension and pelvic adenopathy was well shown, and MRI is very promising as a method for the preoperative staging of known prostatic carcinomas.     

Fibrous dysplasia: magnetic resonance imaging appearance at 1.5 tesla

Fibrous dysplasia has been described in a small number of cases in the literature as showing low signal intensity on T1- and T2-weighted magnetic resonance images. We reviewed magnetic resonance scans of 13 patients with fibrous dysplasia to determine if there might be a characteristic appearance. All lesions had sharply defined borders and were of intermediate signal intensity on T1-weighted images. With T2 weighting, six lesions (46%) showed high signal intensity, four (31%) showed persistent intermediate signal intensity, and three (23%) showed mixed intermediate and high signal intensity. Ten lesions (77%) had inhomogeneous signal intensity and three (23%) had homogeneous signal intensity. We concluded that fibrous dysplasia does not have a characteristic appearance on magnetic resonance imaging. However, magnetic resonance may be helpful in establishing the diagnosis of fibrous dysplasia if low to intermediate signal intensity is seen on both T1- and T2-weighted images. This situation occurred in 54% of our cases, whereas the other 46% had nonspecific signal characteristics indistinguishable from many other bone lesions.     

Fibrogenesis imperfecta ossium: imaging correlation in three new patients

Objective. Fibrogenesis imperfecta ossium is an extremely rare disorder that can easily be misdiagnosed. We retrospectively reviewed the clinical and imaging data of three confirmed cases of fibrogenesis imperfecta. Design and patients. The patients consisted of two men and one woman, ranging in age from 40 to 53 years. Radiography was performed in all the patients. One patient had a 3-year follow-up of the thoracolumbar spine with conventional radiography and thoracolumbar magnetic resonance (MR) imaging. Open biopsy was performed in all cases, confirming the diagnosis of fibrogenesis imperfecta ossium. Results. All our cases demonstrated ”fishnet” trabecular pattern by conventional radiographs, and a pelvis radiograph of one patient showed an equivocal sclerosis pattern. Multiple fractures were noted in two patients. A pseudoexostosis was present in the ilium in one patient. Thoracolumbar MR imaging demonstrated diffuse low signal intensity within the medullary space on both T1-weighed and T2-weighted images, except for a region of increased signal intensity in the L1 and L2 vertebral bodies on T2-weighed images due to edema from acute collapse. Conclusions. Although uncommon, fibrogenesis imperfecta ossium should be considered in a previously healthy patient with a combination of progressive bone pain, unexplained fractures, a radiologic pattern of fishnet osteopenia and MR imaging of low signal intensity bone marrow on both T1-weighted and T2-weighted images. Received: 16 February 1999 Revision requested: 7 April 1999 Revision received: 7 May 1999 Accepted: 19 May 1999     

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.     

Brodie Abscess: MR imaging appearance in 10 patients

The magnetic resonance (MR) imaging features of Brodie abscess have not yet been fully evaluated. Ten patients with Brodie abscess, eight of long bone and two of vertebra, were studied with MR imaging. Long bone abscess had a characteristic “target” appearance with four layers: (a) a center with low signal intensity on T1-weighted images and high signal intensity on T2-weighted and STIR (short-inversion-time inversion recovery) images, (b) an inner ring isointense to muscle on T1-weighted images and with high signal intensity on T2-weighted and STIR images, (c) an outer ring hypoin-tense on all images, and (d) a peripheral halo hypointense on T1-weighted images. In six of eight cases, a soft-tissue mass was found. The two vertebral abscesses had a less specific appearance, with low signal intensity on T1-weighted images and high signal intensity on T2-weighted and STIR images. Only the peripheral halo was clearly identified in both cases.     

Tophaceous gout of the spine: MR imaging features

AIM: To define the magnetic resonance (MR) imaging features of tophaceous gout of the spine. MATERIALS AND METHODS: We present the MR imaging examinations of 4 patients with spinal tophaceous gout. Spin-echo T1-weighted and fast spin-echo T2-weighted images were obtained for all patients, and 2 patients had gadolinium-enhanced MR imaging studies. Corresponding computed tomography (CT) was performed in one patient. All images were evaluated for the characteristics of the gouty tophi. RESULTS: The gouty tophi were located at the lower thoracic (n=1) and lumbar (n=3) levels. All tophi yielded homogeneous intermediate to low signal on T1-weighted images and variable signal intensity on T2-weighted images, comprising small foci of very low signal intensity on all sequences. Gadolinium-enhanced MR imaging studies revealed homogeneous enhancement or heterogeneous peripheral enhancement. Diffuse stippled calcifications were found in the tophi on CT images. Periarticular tophi with juxtaarticular bony erosions around facet joints occurred in 3 patients. CONCLUSION: Spinal tophaceous gout should be considered in the differential diagnosis when periarticular deposits contain very low signal foci on all MR imaging sequences.     

Clinical and in vitro magnetic resonance imaging of prostatic carcinoma

Magnetic resonance imaging (MRI) of the prostate was accomplished in 10 patients who subsequently had surgical exploration for histologic confirmation and tumor staging. Eight patients were found to have carcinoma of the prostate. Two patients had malignancies of the urinary bladder and were treated with radical resection of the bladder and prostate. The prostatic glands in the latter two patients were free of tumor. One gland was entirely normal; the other had extensive acute and chronic prostatitis. Two resected prostates with carcinoma and one normal prostate were available for in vitro MRI in a clinical magnetic resonance unit. The MRI finding of prostatic carcinoma was heterogeneous signal patterns, seen best on T2-weighted studies. A similar pattern was identified in the gland with acute and chronic prostatitis. There was a homogeneous MRI signal pattern of the normal prostate gland examined in vitro. In two instances, the MRI studies were accurate for the identification of tumor spread to the seminal vesicles, not diagnosed at the time of surgical resection. Microscopic metastatic disease of the lymph nodes in four patients was not identified by MRI.     

MR signal of the solid portion of pilocytic astrocytoma on T2-weighted images:is it useful for differentiation from medulloblastoma?

Background and purpose: Although imaging features of cerebellar pilocytic astrocytoma and medulloblastoma have been described in many texts, original comparisons of magnetic resonance intensity between these two tumours are limited. In the present study the results of magnetic resonance imaging (MRI) were reviewed, focusing especially on the signal intensity of the solid portion of these neoplasms. Methods: MR images of ten cerebellar pilocytic astrocytomas and ten medulloblastomas were reviewed. The signal intensities of the solid components were graded on a scale of 1 to 5, with higher scores indicating a signal intensity closer to that of water. The degree of enhancement, tumour cysts and peripheral oedema were evaluated on MR images. When the solid portion was heterogeneous (i.e. mixed signal intensity or degree of enhancement), the dominant area was selected for evaluation. Results: On T2-weighted images, the signal intensity of the solid portion was equal to that of cerebrospinal fluid (CSF) in 50% of pilocytic astrocytomas. No medulloblastomas showed such hyperintensity. Most medulloblastomas (80%) were isointense to grey matter. On T1-weighted images, the signal intensity varied widely in pilocytic astrocytomas; however, all medulloblastomas were iso- or hypointense to grey matter. The MR enhancement pattern, cystic component and peripheral oedema all varied in both tumour types and no specific features were identified. Conclusion: A signal intensity of the solid portion isointense to CSF on T2-weighted images was characteristic of cerebellar pilocytic astrocytomas; this was not observed in medulloblastomas. Attention to T2-weighted imaging of the solid portions of a tumour is easy and helpful in differentiating between cerebellar pilocytic astrocytoma and medulloblastoma.     

Prostatic carcinoma and benign prostatic hyperplasia: MR imaging with histopathologic correlation

Twenty-eight patients with prostatic carcinoma who underwent magnetic resonance (MR) imaging and subsequent radical prostatectomy were studied. The resected prostates were sectioned axially, and the whole-mount prostatic specimen was compared with the corresponding MR images. The carcinoma could be identified in 20 cases (71%), but the tumor volume was underestimated in 12 patients (43%). In 19 of 20 visualized cases (95%), the carcinoma was seen as an area of low signal intensity within the peripheral zone on T2-weighted images. However, in one case the signal intensity of the carcinoma was higher than that of the remainder of the peripheral zone. All carcinomas were located within the peripheral zone. The accuracy of MR imaging in the prediction of extraglandular tumor spread was 82%, with a sensitivity of 37.5% and a specificity of 100%. Nineteen patients (67%) exhibited histologically benign hyperplasia, which could be identified on MR images in 10 cases (53%). The signal intensities of the nodules varied. All areas of benign hyperplasia were located within the central zone. The location of the pathologic changes must therefore be considered in differential diagnosis.     

MRI of extradural spinal tumours at 0.3 T

Ninety-one patients with extradural spinal tumours were examined by magnetic resonance imaging. There were 76 metastases (6 from unknown primary tumours). Seven patients had primary spinal tumours and 8 had multiple myeloma. Sixteen had bulging, diseased vertebral bodies compressing the subarachnoid space and 67 had extradural tumour compressing the spinal cord. Sixty patients had paravertebral involvement. Intraspinal involvement did not correlate with the extent of spinal lesions. All patients had vertebral destruction, with hypointense or combined hypo- and isointense signal relative to bone marrow on T1-weighted images. In most of the 22 patients with T2-weighted images the tumours were isointense or slightly hyperintense. It was usually impossible to differentiate the various tumours on the basis of signal intensity and morphology. However, metastases from carcinoma of the prostate were often more hypointense than other tumours on T1- and T2-weighted images. An inhomogeneous pattern in which diffusely low signal is combined with focal lower signal on T1-weighted images may suggest myeloma. In the 22 patients examined with both T1- and T2-weighted images, T1-weighted images gave the best information in 18; in 3 they were equivalent and in 1 inferior to T2-weighted images; they are therefore recommended for routine imaging of epidural spinal tumours.     

Prosthetic testicle: appearance at MR imaging

The appearance of testicular prostheses on magnetic resonance (MR) images was studied in six patients with seven silicone implants: two with a fluid consistency and five that were solid. On T1-weighted images, both types of prosthesis demonstrated homogeneous low signal intensity; on T2-weighted images, the fluid implants had a uniformly low signal intensity, and the solid implants had a uniformly high signal intensity. Both prostheses created a chemical shift artifact on all imaging sequences owing to the difference in chemical composition of the prostheses and the surrounding tissue.     

Magnetic resonance imaging of myositis ossificans: analysis of seven cases

Myositis ossificans typically presents as soft tissue swelling with progressive ossification on radiographs. Since magnetic resonance imaging (MRI) is commonly used to evaluate soft tissue masses, we analyzed eight MR examinations in seven patients with myositis ossificans to determine if typical patterns were present. One acute lesion had homogeneous intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Two subacute lesions had low signal intensity margins with slightly increased signal intensity centers on T1-weighted images and very high signal intensity on T2-weighted images. Five chronic lesions had two different patterns. All five were well-defined with low signal intensity borders. Three had signal intensity patterns characteristic of fat on T1-weighted and T2-weighted images. The other two lesions had intermediate signal intensity on T1-weighted images and slightly increased signal intensity on T2-weighted images.We conclude that typical MR appearances of myositis ossificans do exist. A low signal intensity rim is a common finding. However, these patterns are not unique to myositis ossificans and resemble those that have been reported in other lesions. It is important to be aware of the spectrum of MR findings of myositis ossificans when considering the differential diagnosis of a soft tissue mass.     

Transient osteoporosis of the hip: MR imaging

Three patients with transient osteoporosis of the hip underwent magnetic resonance (MR) imaging. MR images showed decreased signal intensity of bone marrow in the femur on T1-weighted images and increased signal intensity relative to the intensity of normal bone marrow on T2-weighted images. Joint effusions were seen on MR images of all patients on T2-weighted images. The findings on MR images concurred with histologic findings, such as increased bone turnover and mild inflammatory reaction, in one patient. The clinical symptoms and abnormalities on MR images regressed completely within 6-10 months. Familiarity with the distinct features of transient osteoporosis on MR images may be important in the differential diagnosis of adults with hip pain.     

MR imaging of tuberculous arthritis: Clinical and experimental studies

Signal-intensity characteristics of magnetic resonance (MR) images were assessed in five patients and in 10 rabbits with tuberculous arthritis. MR imaging findings were compared with histologic findings in the animal study. In both of clinical and experimental cases, tuberculous lesions showed both intermediate and high signal intensity on T2-weighted images, while they showed heterogeneously intermediate signal intensity on T1-weighted images. As T2-weighted images were compared with pathologic specimens, intermediate signal intensity corresponded to caseous necrosis, whereas high signal intensity related to granulomas or effusion. Postcontrast T1-weighted images showed enhancement at the peripheries rather than the centers of tuberculous lesions. These results indicate that tuberculous arthritis should be included in the differential diagnosis when intra-articular lesions with low or intermediate signal intensity are found on T2-weighted images.