Magnetic resonance imaging of the pelvis: Prostate and urinary bladder

Magnetic resonance imaging has opened up a new horizon in the evaluation of the male pelvis. Its direct multiplanar imaging and display of the unique tissue contrast allows for the demonstration of prostate anatomy. Prostatic disease, even when confined to the gland, is easily depicted. However, one cannot distinguish benign from malignant processes. In a patient with a known prostatic neoplasm, magnetic resonance is useful as a staging modality. Accuracy in the staging of prostatic malignancies by MRI surpasses that of ultrasound or CT. In the evaluation of the urinary bladder, the greatest advantage of magnetic resonance is its ability to differentiate between a normal bladder, and other pathologic conditions affecting the bladder, including inflammatory, congestive and neoplastic processes. In the evaluation of bladder carcinoma, magnetic resonance is useful as a staging modality. Clinical application of magnetic resonance is just beginning and therefore, the full potential of the modality has yet to be explored.     

Early clinical experience with high-field 1.5 Tesla magnetic resonance imaging

Despite early concerns regarding potential tissue attenuation of signal and lack of inherent contrast, magnetic resonance imaging at 1.5 Tesla has proved to be a valuable extension of magnetic resonance imaging. In this report, we review our initial experience in imaging of the central nervous system, abdomen, chest and pelvis. In the central nervous system, exquisite morphologic detail has been demonstrated. This has added both in terms of sensitivity and specificity to neuroradiologic diagnosis. In the chest and abdomen, despite problems with respiratory and cardiac motion, good morphologic detail can be obtained. In the thorax, our work has demonstrated the ability of magnetic resonance imaging to clearly define the relationship of masses to the hilum and mediastinum. Imaging of the great vessels with magnetic resonance imaging has also proved useful. In the abdomen, magnetic resonance imaging has been useful in looking at the extent of masses identified, in characterizing focal liver masses, and in staging a variety of neoplasms. The high contrast resolution and the ability to image in a variety of planes is particularly helpful in the pelvis. In the male pelvis our work has primarily dealt with staging extracapsular prostatic carcinoma. In the female pelvis, ascertaining the nature of adnexal masses and defining staging primary carcinomas and their response to therapy has been the major thrust of our efforts. Surface coils and other technical improvements will undoubtedly extend the range of application at high field.     

Role and limitations of magnetic resonance imaging in the diagnostic work-up of patients with liver cancer

The main objectives of liver imaging are detection and characterization of focal liver lesions. There is a wide range of imaging modalities available for the work-up of patients with liver cancer. In the current environment of cost containment, the most appropriate modality should be chosen to answer the clinical question. Contrast-enhanced computed tomography is currently the modality of choice for liver imaging for routine applications. Until recently magnetic resonance imaging was used only as a problem solving technique for lesions that were equivocal after contrast-enhanced computed tomography. However magnetic resonance with the use of tissue specific contrast agents, has already challenged the role of computed tomography portography in preoperative staging of liver cancer, and may soon completely replace this technique. It is also the primary modality for screening patients with cirrhosis for hepatocellular carcinoma. This review describes the role of magnetic resonance imaging, in the evaluation of patients with liver cancer, and outlines a rational approach for the diagnostic work-up of these patients.     

Role of magnetic resonance imaging as an adjunct to clinical staging in cervical carcinoma

Magnetic resonance imaging depicts the morphological details of the female pelvis and is useful for evaluating both benign and malignant cervical masses. Clinical assessment of the extent of cervical cancer is crucial in determining the optimal treatment strategy, but clinical staging by itself has limitations. Clinical staging, as defined by FIGO (International Federation of Gynecologic Oncology), is based on the findings of physical examination, lesion biopsies, chest radiography, cystoscopy, and renal sonography and can be erroneous, depending on the stage of the disease, by 16% to 65%. The prognosis of cervical cancer is determined not only by stage, but also by nodal status, tumor volume, and depth of invasion, none of which are included in the FIGO guidelines. Magnetic resonance imaging has been described as the most accurate, noninvasive imaging modality in staging cervical carcinoma. This review outlines the magnetic resonance features of normal cervix, primary disease (by stage), and recurrent disease and discusses the role of magnetic resonance imaging in staging and clinical decision making.     

Imaging axillary lymph nodes in patients with newly diagnosed breast cancer

The presence of axillary lymph node metastasis in patients newly diagnosed with breast cancer carries significant prognostic and management implications. As a result, there is increasing interest to stage accurately the axilla with preoperative imaging to facilitate treatment planning. Currently, the most widespread imaging techniques for the evaluation of the axilla include ultrasound and magnetic resonance imaging. In many settings, the ability to detect axillary lymph nodes containing metastases with imaging and image-guided biopsy can allow surgeons to bypass sentinel lymph node dissection and proceed with full axillary lymph node dissection. However, no imaging modality currently has sufficient negative-predictive value to obviate surgical staging of the axilla if no abnormal lymph nodes are detected. Promising advanced imaging technologies, such as diffusion-weighted imaging and magnetic resonance lymphangiography, hold the potential to improve the accuracy of axillary staging and thereby transform management of the axilla in patients newly diagnosed with breast cancer.     

Carcinoma of the uterus: use of gadopentetate dimeglumine in MR imaging

This prospective study assessed the role of gadopentetate dimeglumine-enhanced magnetic resonance imaging in the detection and staging of carcinomas of the endometrium and cervix. Surgical-pathologic findings were used as the standard of reference. In the evaluation of endometrial carcinoma, contrast-enhanced imaging improved tumor detection and differentiation between viable tumor and retained debris. Use of contrast material significantly improved the staging accuracy. The ability to assess the depth of myometrial invasion was also improved. In the evaluation of cervical carcinoma, assessment of tumor location and size did not improve following contrast enhancement. Use of gadopentetate dimeglumine resulted in overestimation of stromal, parametrial, vaginal, and/or bladder wall invasion in eight patients. However, evaluation of intratumoral architecture and large lesions was easier with contrast-enhanced imaging. When only stage II and higher disease was analyzed, use of contrast material improved the evaluation of disease extent. The authors conclude that gadolinium enhancement adds to the accuracy of evaluation of endometrial carcinoma but is useful in only advanced cases of cervical carcinoma.     

Evaluation of prostate size: a comparison of ultrasound and magnetic resonance imaging

To determine the relative accuracy of ultrasonography (US) and magnetic resonance imaging (MRI) in the evaluation of prostate volume, we compared US and MR images with surgical findings in 15 patients. Transabdominal US was excellent for determining prostate size in patients with small to moderate enlargement. When compared with surgical specimens, the difference between the weight of the gland as predicted by US and the actual weight was 14% (SD +/- 12). With the transabdominal approach, the length was often inaccurately imaged, but the addition of transrectal scans in the sagittal projection improved results: with combined transabdominal and transrectal US, the average difference in weight was 8% (SD +/- 7). The MRI more accurately predicted prostatic volume (average difference, 6% (SD +/- 6), but the difference between the latter 2 is not significant. In 5 additional patients who had undergone transurethral resection of the prostate, residual prostatic tissue was evaluated by MRI and US. In addition to demonstrating prostate size, transrectal sagittal US showed the relationship among the bladder neck, prostatic urethra, and remaining prostatic tissue. Real-time US also allowed evaluation of dynamic sphincteric contractions, which is a finding not available today with MRI. Tissue differentiation was attempted with both MRI and US. Neither imaging modality could differentiate benign from malignant disease.     

Breast magnetic resonance imaging: state of the art and clinical applications

Breast magnetic resonance imaging is a modality that is being progressively integrated into the breast radiologist's daily clinical practice. There is consensus on the minimal technical requirements that a breast MR exam should have in order to attain diagnostic quality. Diagnostic criteria are mainly based on the American College of Radiology's BI-RADS magnetic resonance imaging categories. Breast cancer staging is a main clinical application, but it is not universally accepted. Other applications are: response evaluation in patients treated with chemotherapy, screening in high-risk patients, cancer of unknown origin, assessment of a possible relapse and breast implant evaluation.     

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.     

State-of-the-art cross-sectional imaging in bladder cancer

Advances in cross-sectional imaging have given radiology an increasingly significant role in the diagnosis, staging, and restaging of patients with bladder cancer. The primary role of computed tomography (CT) in bladder cancer is for tumor staging and screening for distant metastases. Multidetector-row CT may improve the evaluation of bladder tumors by overcoming the difficulties of previous generations of CT in detecting invasion of contiguous organs and nodal staging. Magnetic resonance imaging (MRI) however is still considered superior to CT for primary staging of bladder carcinoma. The multiplanar capability of MRI with its superior soft-tissue resolution offers improved evaluation of local staging of bladder tumors. Positron emission tomography/CT is emerging as a novel-imaging tool for the detection of distant metastases. In this review, we emphasize the value of current cross-sectional imaging and discuss the potential applications of novel imaging techniques in the management of patients with bladder cancer, predominantly transitional cell carcinoma.     

Characterization of pancreatic adenocarcinoma by magnetic resonance imaging

In the past, magnetic resonance imaging (MRI) of the pancreas has suffered from many technical obstacles that have precluded success, particularly in the evaluation of adenocarcinoma. However, with the improved quality of pancreatic MRI and the use of intravenous gadolinium as a contrast agent, MRI is now proving useful in the evaluation of pancreatic adenocarcinoma. MRI's main role is in accurate preoperative staging when computed tomography and ultrasonography provide equivocal results.     

Diagnostic imaging of carcinomas of the gallbladder and the bile ducts

Early diagnosis and accurate staging of carcinomas of the gallbladder and the bile ducts are helpful in improving the prognosis. Ultrasonography (US), a useful initial modality when exploring the background of jaundice or non-specific gastrointestinal complaints, sensitively reveals bile duct obstruction in particular. In unclear cases, or if US suggests a resectable biliary malignancy, computed tomography (CT), magnetic resonance imaging (MRI) with magnetic resonance cholangiography (MRC) and / or traditional cholangiography often provide additional information, and imaging-guided fine-needle biopsy or an endoscopic brush sample may verify the malignant nature of the tumor. Complementary modalities are usually needed for accurate staging, and traditional cholangiography is often performed for therapeutic purposes as well. Comparative studies of MRI with MRC and multidetector CT in biliary cancers would be welcome.     

Prostatic carcinoma: staging by clinical assessment, CT, and MR imaging

The sensitivity, specificity, accuracy, and positive and negative predictive values of clinical assessment, computed tomography (CT), and magnetic resonance (MR) imaging were compared in the differentiation of stage B from stage C prostatic carcinoma. Forty-six patients who had undergone radical prostatectomy were included in the study. Surgical-pathologic staging was considered the "truth measure." Clinical staging had an accuracy of 61%, and CT, 65%. Accuracy for MR imaging depended on the instrument parameters and plane of section used. When only transverse T1-weighted images were analyzed, MR accuracy was 61%. However, when transverse T1- and T2-weighted images supplemented by additional T2-weighted coronal or sagittal images were studied, accuracy increased to 83%. At present, MR imaging is the most accurate diagnostic modality for the local staging of carcinoma of the prostate, but for optimal results, multiple sequences and two orthogonal planes of imaging are needed.     

Pictorial review: magnetic resonance imaging of colonic diverticulitis

Magnetic resonance imaging (MRI) is rapidly emerging as a useful imaging modality for the evaluation of the gastrointestinal tract. Increasingly rapid sequences and improving hardware have significantly improved the visualisation of diseases of the colon. MRI has a major advantage over CT in that there is no ionising radiation. In our institution, MRI has increasingly been used as a complimentary imaging modality to CT in the diagnosis and evaluation of diverticulitis and its complications. In this review article, we illustrate the emerging role of MRI in the diagnosis and evaluation of colonic diverticulitis.     

List of Exhibitors

Technical advances in magnetic resonance imaging (MRI), notably in high-resolution MRI, have opened up new diagnostic applications in male pelvic pathology. A major indication is the preoperative staging of prostate cancer, where MRI is more reliable than other imaging modalities in differentiating between localized and advanced disease. In monitoring local recurrence after radical prostatectomy MRI is also valuable in differentiating scar tissue from new growth. In benign prostate disease, MRI effectively displays the congenital cysts that may be associated with infertility. Other disease, however – notably benign prostatic hyperplasia – is generally an incidental finding. Ultrasound remains the imaging modality of choice for evaluation of pathologies of the penis, testis and scrotum, e. g. in differentiating malignant from benign scrotal masses or in diagnosing acute scrotum due to testicular torsion or rupture. In isolated cases, MRI is also a valuable diagnostic aid in conditions of these organs, e. g. in the preoperative localization of ectopic testes in cryptorchidism or if US findings are equivocal. Received 28 May 1998; Revision received 13 July 1998; Accepted 17 July 1998     

MR imaging of the male and female urethra.

Conventional radiographic contrast material-enhanced studies (eg, retrograde urethrography [RUG], voiding cystourethrography [VCUG], double-balloon catheter urethrography) and ultrasonography are useful in evaluating the anatomy of the urethra but are limited in demonstrating anatomic derangement of adjacent structures. Since the anatomic details of both the urethra and periurethral tissues can be evaluated noninvasively with magnetic resonance (MR) imaging, this modality can be used as an adjunctive tool for evaluation of urethral abnormalities. In patients with congenital anomalies, MR imaging is reserved for cases of intersex anomalies or complex genitourinary anomalies, in which evaluation of internal organs is essential. MR imaging may demonstrate diverticula that are not seen on radiographic contrast-enhanced studies, including VCUG, RUG, or double-balloon catheter study. In cases of inflammation, MR imaging can demonstrate not only inflammatory infiltration around the urethra but also the presence of a periurethral abscess or sinus tract. In cases of trauma, MR imaging is helpful in assessing the presence and extent of anterior or posterior urethral injury and predicting the occurrence of complications. At MR imaging, a fistula can be seen as a direct communicating channel with an adjacent organ. In patients with urethral tumors, the major role of MR imaging is in local staging.     

Fluorine-18-deoxyglucose-positron emission tomography imaging with magnetic resonance and computed tomographic correlation in the evaluation of bone and soft-tissue sarcomas: a pictorial essay

Positron emission tomography (PET) imaging has a growing role as an imaging modality to be used in conjunction with magnetic resonance and computed tomographic imaging in the detection, staging, and management of many sarcomas and carcinomas. Since PET is a relatively new modality and the incidence of sarcomas is low, it has not yet been approved for use in all bone and soft-tissue sarcomas. The purpose of this article is to pictorially evaluate soft-tissue and bone sarcomas, including malignant peripheral nerve sheath tumor, synovial sarcoma, osteosarcoma, liposarcoma, rhabdomyosarcoma, malignant fibrous histiocytoma, fibrosarcoma, and myxofibrosarcoma. This pictorial essay illustrates and describes these tumors in various stages of disease progression vis-à-vis fluorine-18-deoxyglucose-PET imaging with computed tomographic and magnetic resonance correlation. Various stages of disease progression will be discussed including initial diagnosis, treatment response, and metastatic involvement.     

A systematic approach to magnetic resonance imaging interpretation of sports medicine injuries of the shoulder

Magnetic resonance imaging has developed as a useful imaging modality in the evaluation of the athlete with shoulder pain. The multiplanar capabilities of magnetic resonance imaging make it ideal for detecting the anatomical variations of the osseous outlet that may contribute to the clinical syndrome of impingement. Its superb soft tissue contrast and spatial resolution allow for accurate differentiation between tendinopathy, partial-thickness tear, and full-thickness tear of the rotator cuff and also allow for detection of the subtle lesions of the capsule and labrum that are associated with shoulder instability. However, to accurately interpret the numerous images and pulse sequences obtained in a standard magnetic resonance examination of the shoulder, it is helpful to have a systematic approach to ensure that each of the pertinent anatomical structures are evaluated. This article will provide a systematic approach to the interpretation of a magnetic resonance examination of the shoulder. The normal imaging appearance of each anatomical structure will be described, and the most useful pulse sequences and imaging planes for the evaluation of each structure will be discussed. Finally, the signs of injury will be described and illustrated.     

Magnetic resonance imaging, computed tomography and endosonography in the local staging of carcinoma of the cervix

Thirty-seven patients with carcinoma of the cervix were prospectively staged by examination under anaesthesia (EUA), transvaginal and transrectal ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI). Pathological correlation was available for 20 patients. In the pathologically staged patients, EUA agreed with the staging in 17, understaging three patients. Endosonography agreed with the staging in 19, CT in 16 and MRI in 18 patients. For the remaining 17 patients, endosonography agreed with the EUA findings in 13, CT in 12 and MRI in 12. This study has shown that endosonography and MRI are more accurate than CT in the local staging of carcinoma of the cervix. Computed tomography was least accurate in staging early tumours and differentiating between Stage Ib and IIb disease. Lymph node involvement was detected with equal frequency by both CT and MRI. Magnetic resonance imaging was useful in identifying vaginal and bladder wall involvement and in one patient showed features due to an unsuspected early pregnancy.     

Zervixkarzinom

The treatment of uterine cervical carcinoma is largely dependent on the tumor stage. Despite significant inaccuracies in the clinical examination, uterine cervical cancer remains the only gynecological form of cancer still largely staged according to clinical findings. Although imaging is still not included in the staging the recently published revised FIGO (Fédération International de Gynécologie et d'Obstétrique) system encourages the use of modern cross-sectional imaging (magnetic resonance imaging MRI and computed tomography CT). Due to its high soft tissue contrast MRI allows excellent non-invasive assessment of the cervix with direct tumor delineation as well as assessment of the prognosis based on morphological factors. Studies in the literature report an accuracy of 93% for MRI in the preoperative assessment of tumor size and in the differentiation of operable from advanced cervical cancer. Therefore MRI is considered to be the optimal modality for diagnostic evaluation starting from FIGO stage IB1, for radiation therapy planning, and for exclusion of recurrence in follow-up. In this paper we give an overview of the role of magnetic resonance imaging in preoperative staging of uterine cervical cancer.