Integration of breast MRI in clinical trials

Clinical trials are the mechanism for implementing new treatment methods into clinical practice. A number of organizations have been developed to facilitate the initiation, implementation, and data analysis for clinical trials. Imaging is important for patient selection and establishment of endpoints, yet imaging expertise has been underrepresented in most clinical trial groups. The integration of breast MRI in clinical trials is an important step toward the establishment of this method of imaging in routine practice. In addition, these data will be important in justifying the expense of MRI to payer organizations. The potential roles of breast MRI in clinical trials are reviewed. These breast MRI applications are linked with some of the studies that are under development. It is important for the MRI community to be aware of the importance of clinical trials in the future clinical establishment of breast MRI. J. Magn. Reson. Imaging 2001;13:830-836.

MR-guided minimally invasive procedures

This article outlines the integration of breast MR imaging minimally invasive therapy for breast tumors. Technical obstacles discussed include accurate determination of margins, DCIS, and localization methods. Treatment methods such as cryotherapy, interstitial hyperthermia, and focused ultrasound are discussed. Other subjects include the amount of minimally-invasive therapy performed to date and the ethical dilemma of clinical trials.

Efficacy and safety of mangafodipir trisodium (MnDPDP) injection for hepatic MRI in adults: results of the U.S. Multicenter phase III clinical trials. Efficacy of early imaging

The efficacy of contrast-enhanced magnetic resonance imaging (MRI) for detecting and characterizing, or excluding, hepatic masses was assessed in 404 patients, following the intravenous administration of mangafodipir trisodium (MnDPDP) injection, a hepatic MRI contrast agent. An initial contrast-enhanced computed tomography (CT) examination was followed by unenhanced MRI, injection of MnDPDP (5 micromol/kg IV), and enhanced MRI at 15 minutes post injection. Agreement of the radiologic diagnoses with the patients' final diagnoses was higher for enhanced MRI and for the combined unenhanced and enhanced MRI evaluations than for unenhanced MRI alone or enhanced CT using the clinical diagnosis as the gold standard. Mangafodipir-enhanced MRI uniquely provided additional diagnostic information in 48% of the patients, and patient management was consequently altered in 6% of the patients. MnDPDP-enhanced MRI was comparable or superior to unenhanced MRI and enhanced CT for the detection, classification, and diagnosis of focal liver lesions in patients with known or suspected focal liver disease.

Safety and efficacy of mangafodipir trisodium (MnDPDP) injection for hepatic MRI in adults: results of the U.S. multicenter phase III clinical trials (safety)

The short-term safety of mangafodipir trisodium (MnDPDP) injection was studied in 546 adults with known or suspected focal liver lesions. An initial contrast-enhanced computed tomography examination was followed by unenhanced magnetic resonance imaging (MRI), injection of MnDPDP (5 micromol/kg), and enhanced MRI. Adverse events were reported for 23% of the patients; most were mild to moderate in intensity, did not require treatment, and were not drug related. The most commonly reported adverse events were nausea (7%) and headache (4%). The incidence of serious adverse events was low (nine events in six patients) and not drug related. Injection-associated discomfort was reported for 69% of the patients, and the most commonly reported discomforts included heat (49%) and flushing (33%). Changes in laboratory values and vital signs were generally transient, were not clinically significant, and did not require treatment. There were no clinically significant short-term risks from exposure to MnDPDP.

Role of breast magnetic resonance imaging in determining breast as a source of unknown metastatic lymphadenopathy

BACKGROUND

Occult primary breast cancer (OPBC) represents less than 1% of breast cancer. In only a third of cases, mammography identifies a primary tumor. We hypothesized that rotating delivery of excitation off-resonance breast magnetic resonance imaging (MRI) would identify or exclude the breast as a primary site in patients with OPBC.

METHODS

In a retrospective review, 10 patients were identified with OPBC in which MRI was performed. Malignant appearing lesions were correlated with histopathologic findings at biopsy or surgery.

RESULTS

MRI identified the primary site in 8 of 10 cases as breast (80%), and excluded it in 2 cases. The extent of disease and location was accurately predicted when compared with histopathologic specimen.

CONCLUSIONS

As we continue to focus on a cure of early breast cancer, it is imperative that diagnostic images become more sensitive and specific. MRI accurately predicted OPBC in this subset of patients.

Integration of breast magnetic resonance imaging with breast cancer treatment

High-contrast, high-resolution breast magnetic resonance imaging (MRI) is a highly accurate method for determining the extent of breast cancer. This information can be used to improve therapy by better defining the extent of surgery needed, coordinating additional surgery if the initial surgery results in positive pathological margins, and determining the effectiveness and extent of residual disease following nonsurgical therapy. The use of stereotaxic biopsy and localization is an essential component for extending the use of breast MRI in therapeutic applications. The clinical value of therapeutic management with breast MRI information is expected to result in commercially available tools in the near future.

Breast magnetic resonance imaging

Breast MRI is becoming an important tool for the improved management of breast cancer. The technical attributes of high contrast, high-resolution breast MRI acquisitions are summarized. The fundamentals of image interpretation are outlined, including lesion enhancement, morphological features, and extent categories. The indications for breast MRI include compromised mammography, staging of disease within the breast and adjacent structures, difficult histology, and other special diagnostic situations. Patients with compromised mammography include previous surgery, radiographically dense breasts, and silicone augmentation. The improved determination of disease extent aids in the management of breast conservation treatment. Certain lesions, particularly lobular carcinoma and ductal carcinoma in situ, can be better managed with the information available with breast MRI. Other potential indications are also discussed, including patients presenting with positive axillary nodes and no known primary, women with a high risk of malignancy, and recently postoperative breasts with positive margins. The need for MRI stereotaxis is reviewed, with indications and potential solutions. The potential future roles for MRI-directed interstitial hyperthermia are outlined.

A physics-based coordinate transformation for 3-D image matching

Many image matching schemes are based on mapping coordinate locations, such as the locations of landmarks, in one image to corresponding locations in a second image. A new approach to this mapping (coordinate transformation), called the elastic body spline (EBS), is described. The spline is based on a physical model of a homogeneous, isotropic three-dimensional (3-D) elastic body. The model can approximate the way that some physical objects deform. The EBS as well as the affine transformation, the thin plate spline [1], [2] and the volume spline [3] are used to match 3-D magnetic resonance images (MRI's) of the breast that are used in the diagnosis and evaluation of breast cancer. These coordinate transformations are evaluated with different types of deformations and different numbers of corresponding (paired) coordinate locations. In all but one of the cases considered, using the EBS yields more similar images than the other methods.

Detection with MR imaging of residual tumor in the breast soon after surgery

OBJECTIVE

Difficulties in the preoperative assessment of tumor size and extent result in a positive pathologic margin in up to 70% of patients undergoing breast conservation surgery. Although positive margins usually require reexcision, the location and extent of surgery required are often difficult to establish by current imaging techniques. We investigated the accuracy of three-dimensional rotating delivery of excitation off resonance (3D RODEO) MR imaging of the breast in revealing the presence and extent of residual tumor within the breast soon after surgery.

MATERIALS AND METHODS

Nineteen patients who had undergone lumpectomy or excisional biopsy were evaluated with contrast-enhanced 3D RODEO MR imaging of the breast within 10 months after surgery. The MR imaging results were correlated with serial-sectioned mastectomy or partial mastectomy specimens from 18 patients and with a clinical and mammographic follow-up examination in one patient.

RESULTS

We found that 3D RODEO MR imaging accurately revealed the presence or absence and the location and extent of recurrent tumor in 15 of the 18 patients who had pathologic confirmation. Of the three MR imaging-pathology mismatches, two had irregular or nodular enhancement that corresponded to microabscesses. The third mismatch showed multicentric disease on MR imaging but only single-quadrant lobular carcinoma at pathologic examination. Our 19th patient showed no evidence of recurrent tumor on MR imaging or at 2-year follow-up clinical and mammographic examinations.

CONCLUSION

MR imaging with 3D RODEO technique correctly revealed the presence or absence, the location, and the extent of recurrent tumor in 84% of patients who had recently undergone breast surgery.

MR imaging in the management before surgery of lobular carcinoma of the breast: correlation with pathology

OBJECTIVE

Our objective was to investigate the use of MR imaging in preoperative staging and characterization of lobular carcinoma.

MATERIALS AND METHODS

MR imaging studies and mammographic studies in 20 patients with infiltrating lobular carcinoma were evaluated and correlated with pathology findings on serially sectioned tissue. The MR images and mammograms were reviewed retrospectively by three independent examiners unaware of the clinical, imaging, and pathology findings.

RESULTS

The extent of disease found pathologically correlated with that predicted by MR imaging studies in 85% of patients, compared with a 32% correlation (p < .0001) with mammographic studies. Interobserver agreement on lesion morphology and extent of disease was higher for MR imaging (91% and 100%, respectively) than for mammography (64% and 91%, respectively). The retrospective MR readings did not differ from the prospective reports. No false-positive lymphadenopathy was interpreted on MR imaging. Lymph nodes having metastatic lobular carcinoma on the pathology examination were missed on MR imaging in four patients.

CONCLUSION

MR imaging is significantly more accurate than mammography in determining the extent of disease and characterizing the morphology of infiltrating lobular carcinoma. MR imaging may play a role in preoperative planning, especially when breast conservation is being considered.

MRI in breast cancer diagnosis and treatment

Breast cancer diagnosis and treatment are important health care issues in the Industrialized World. About 180,000 new breast cancers are discovered annually in the United States. Because this cancer often occurs in premenopausal women, breast cancer is a leading cause of potential life years lost. Breast magnetic resonance imaging (MRI) is capable of producing detailed information concerning the extent and character of breast lesions. The technique and alternatives for generating high-resolution breast MR images are reviewed. Characteristic features of a pulse sequence for breast imaging includes heavy T1 weighting and magnetization transfer weighting for more effective gadolinium contrast, fat suppression, and rapid acquisition time. MRI is best employed for breast cancer diagnosis as a supplement to conventional breast imaging. Diagnostic groups particularly well suited to breast MRI include women with radiographically dense breasts, silicone augmentation, and postoperative scar. The capacity of breast MRI to show disease extent is employed to plan and localize for breast-conservation therapy. Tumor size and multiple tumors can be characterized for more-effective surgical management. Ductal carcinoma in situ can be imaged and staged for tailored therapy. MRI-directed biopsy and localization can be used to optimize lumpectomy surgery and reduce the potential for histologically positive margins. MRI can define the effectiveness of radiation therapy and chemotherapy to provide improved information on nonsurgical treatment of breast cancer. The clinical implementation of breast MRI in the future depends on the careful coordination of quality MRI images and interpretations with skillful therapeutic management.

Three-dimensional RODEO breast MR imaging of lesions containing ductal carcinoma in situ

PURPOSE

To assess whether rotating delivery of excitation off resonance (RODEO) breast magnetic resonance (MR) imaging can help detect ductal carcinoma in situ (DCIS) lesions, determine tumor extent, and differentiate pure DCIS from DCIS with an invasive component.

MATERIALS AND METHODS

Twenty-two patients with DCIS lesions were evaluated with three-dimensional RODEO MR imaging. Nineteen patients had available mammograms for review.

RESULTS

MR imaging enabled detection of all 22 cases of DCIS, DCIS with microinvasion, or invasive ductal carcinoma with extensive intraductal component. A clumped enhancement pattern was seen on MR images in all cases of pure DCIS. Spiculated enhancement was seen in four of six (67%) patients who had DCIS with microinvasion and in nine of 11 (82%) who had invasive ductal carcinoma with extensive intraductal component. RODEO MR imaging enabled accurate determination of tumor extent in 21 of 22 (95%) patients. Mammography depicted 18 of 19 DCIS lesions. No mammographic feature helped differentiate pure DCIS from DCIS with microinvasion. Mammography enabled accurate determination of tumor extent in 14 of 19 (74%) patients.

CONCLUSION

Three-dimensional RODEO MR imaging can be an adjunct to mammography because of its ability to enable better determination of tumor extent and differentiation of pure DCIS from DCIS with an invasive component.

Evaluation of neoadjuvant chemotherapeutic response of locally advanced breast cancer by magnetic resonance imaging

BACKGROUND

The implementation of new treatment protocols for locally advanced breast cancer is currently limited by inaccurate evaluation of response to neoadjuvant chemotherapy. A recently developed dedicated breast magnetic resonance imaging (MRI) method (RODEO MRI) was evaluated as a tool for determining tumor response and extent of residual disease after neoadjuvant chemotherapy.

METHODS

Thirty-nine patients with Stage II, III, or IV breast carcinoma were prospectively evaluated prior to and following neoadjuvant chemotherapy by MRI, physical examination, and mammography. Assessment of response determined by the three methods was compared. In addition, detailed pathologic correlation of residual disease was determined by serial sectioning of 31 mastectomy specimens from 30 patients. Nine patients had breast conservation, and were included in the response evaluation only. Estimates of tumor response were made by both surgical and medical oncologists. Independent interpretations of MRI studies without knowledge of clinical response were made by three radiologists.

RESULTS

The surgical oncologists assessed complete response (CR), partial response (PR), and no response (NR) in 11, 22, and 7 cases, respectively. The medical oncologists assessed CR, PR, and NR in 12, 21, and 7 cases, respectively. The surgical and medical oncologists' clinical assessment of response agreed with the results of MRI in 52% and 55% of cases, respectively, and with each other in 30 of 40 cases (75%). Mammography correlated with MRI response in only 52% of cases. However, MRI accurately predicted the pathologic determination of residual disease in 30 of 31 cases (97%). There was no disagreement in the assessments of residual disease or response among the three radiologists.

CONCLUSIONS

RODEO breast MRI accurately estimates residual disease after induction chemotherapy. It assesses response to neoadjuvant chemotherapy better than traditional methods of physical examination or mammography. The information obtained from this MRI technique may be used as an objective tool during clinical trials, and to select patients better for breast conservation after neoadjuvant chemotherapy for locally advanced disease.

MRI efficacy and effectiveness research: who needs it and who pays for it?

Health care reform has made quality efficacy research in MRI important to an increasing number of audiences. Historically, the deficit of quality outcomes research in MRI was due to difficulties in study design, lack of funding, disincentives for researches and funding sources, and poor coordination. These issues would be best addressed by the formation of an MRI implementation group that would coordinate funding, planning, and dissemination of the outcomes research efforts.

Hepatic MR imaging with ferumoxides: a multicenter clinical trial of the safety and efficacy in the detection of focal hepatic lesions

PURPOSE

To assess the safety and diagnostic efficacy of intravenous ferumoxides, a superparamagnetic iron oxide, for depiction of focal hepatic lesions on magnetic resonance (MR) images.

MATERIALS AND METHODS

This open-label study included 208 patients with known or suspected focal hepatic lesions. MR images were obtained before and 45 minutes to 4 hours after intravenous infusion of ferumoxides (10 mumol/kg). The effect of ferumoxides on signal intensity of the liver was assessed with quantitative analysis. Safety was evaluated with patient monitoring and laboratory measurements.

RESULTS

Mean lesion-to-liver contrast-to-noise ratio on T2-weighted images was 9.1 on unenhanced images and 12.7 on enhanced images. Signal intensity of normal liver on enhanced images decreased to 37% of that on unenhanced images. In blinded image evaluations, additional lesions were identified on 27% of enhanced images. No serious adverse events occurred.

CONCLUSION

Ferumoxides is a safe and efficacious contrast agent for the detection of focal liver lesions on T2-weighted images.

Silicone-suppressed 3D MRI of the breast using rotating delivery of off-resonance excitation

OBJECTIVE

A new silicone-suppressed MR technique was developed, and its efficacy in identifying free silicone and differentiating it from other breast tissues was investigated.

MATERIALS AND METHODS

Silicone-suppressed MRI was performed using the RODEO (rotating delivery of excitation off-resonance) pulse sequence, which selectively eliminated signal from the narrow range of (CH3)4Si resonance. Ninety breasts in 61 patients were evaluated with both a fat-suppressed 3D MR sequence and a silicone-suppressed 3D MR sequence.

RESULTS

Extracapsular free silicone and silicone injections demonstrated a unique appearance compared with normal breast tissue in all cases. Magnetic resonance identified free silicone in 26 breasts, 10 of which were confirmed pathologically or from a history of previous silicone injections. No free silicone was present on MR in 64 breasts; 8 of these were confirmed by biopsy or mastectomy as showing no evidence of free silicone. This technique was useful in evaluation of prosthesis integrity, free silicone, focal palpable or mammographic lesions, and the breast with silicone injections.

CONCLUSION

Silicone-suppressed RODEO MRI of the breast can accurately identify free and intracapsular silicone and can distinguish silicone from other tissues. This provides unique information about the breast in a number of specific applications.

MR imaging of the breast: current status and future potential

Current and potential roles for MR imaging in the management of breast disorders are reviewed along with the specific technical requirements for each application. Major topics include (1) evaluating breasts before biopsy to reduce the number of surgical biopsies for benign lesions, (2) staging of breast carcinoma in breast conservation candidates, (3) evaluating breasts with inconclusive conventional imaging, (4) coordination of minimally invasive surgery, and (5) evaluating silicone implant integrity.

Staging of breast cancer with MR imaging

The vastly improved sensitivity of new MR methods can be used to define disease within the breast that cannot be seen with conventional breast imaging methods. Breast MR imaging is expected to have a significant role for the staging of breast cancer in breast conservation candidates. Ultimately, breast MR will be integrated with interstitial laser photocoagulation as a treatment method for breast cancer.

Phase III multicenter trial of high-dose gadoteridol in MR evaluation of brain metastases

PURPOSE

To assess the efficacy and safety profile of high-dose (0.3 mmol/kg cumulative dose) gadoteridol in patients with suspected central nervous system metastatic disease.

METHODS

We studied 67 patients using an incremental-dose technique. Patient monitoring included a medical history, physical examination, vital signs, and extensive laboratory tests within 24 hours before and after the MR examination. Precontrast T1- and T2-weighted spin-echo studies were performed, followed by intravenous injection of 0.1 mmol/kg of gadoteridol. T1-weighted images were acquired immediately after and at 10 and 20 minutes after injection. At 30 minutes an additional 0.2 mmol/kg of gadoteridol was administered (0.3-mmol/kg cumulative dose), and T1-weighted images were acquired. Cases demonstrating abnormal MR findings were assessed for efficacy by unblinded and blinded reviewers and were analyzed quantitatively.

RESULTS

Three adverse effects in two patients were considered to be related to gadoteridol administration. No adverse effects were serious; all self-resolved. Forty-nine cases showed abnormal MR findings and were included in the efficacy analysis. A significantly greater number of lesions was seen on the high-dose as opposed to the standard-dose images. Blinded and unblinded readers identified 5 and 8 patients, respectively, with solitary lesions on standard-dose examination and multiple lesions on high-dose examination. Two patients who had normal standard-dose findings had lesions identified on high-dose studies. Quantitative analysis of 133 lesions in 45 patients demonstrated significant increases in lesion signal intensity on high-dose studies when compared with standard-dose studies.

CONCLUSION

Gadoteridol can be safely administered up to a cumulative dose of 0.3 mmol/kg. High-dose contrast studies provide improved lesion detectability and additional diagnostic information over studies performed in the same patients with a 0.1-mmol/kg dose and aid in patient diagnosis and treatment. High-dose gadoteridol study may facilitate the care of patients with suspected central nervous system metastasis.

New horizons in the diagnosis and treatment of breast cancer using magnetic resonance imaging

A new nuclear magnetic resonance imaging (MRI) technique, Rotating Delivery of Excitation Off-resonance (RODEO), has been developed to assist surgeons in the diagnosis and treatment of breast cancer. A nonrandomized, prospective study of 100 patients with a high suspicion of breast cancer was conducted; these patients were examined by RODEO and conventional breast imaging, including mammography. Forty-one breasts were removed by mastectomy; each pathologic specimen was examined by sectional analysis. This study was undertaken to determine the extent that RODEO can aid in detecting breast tumors (including multicentric disease) and in evaluating candidates for conservative breast surgery. RODEO detected 85 pathologically confirmed lesions, 64 of which proved to be malignant. RODEO had a sensitivity of 95%, compared with a sensitivity of 58% for conventional imaging. More study is needed to determine distinguishing MRI characteristics that are suspicious for malignancy. RODEO may be used clinically to assess multicentricity and response to chemotherapy.

MR imaging of the breast with rotating delivery of excitation off resonance: clinical experience with pathologic correlation

An investigative study was undertaken to determine the potential for a new magnetic resonance (MR) imaging technique, RODEO (rotating delivery of excitation off resonance), for use as a diagnostic imaging tool for the breast. The RODEO technique provides fat suppression with T1 weighting and is ideal for gadolinium-enhanced breast imaging. It is a short repetition time, steady-state sequence for high-resolution three-dimensional acquisitions and provides a clinically efficient imaging time of approximately 5 minutes for 128 sections. Imaging findings were correlated with serially sectioned pathologic specimens in 30 breasts with 47 malignant and 27 benign lesions. MR imaging had a sensitivity of 94% and a specificity of 37%. MR imaging depicted additional cancers not seen at mammography in 11 of the 30 patients (37%). The lesions not seen at mammography varied in size from 3 mm to 12 cm. RODEO MR imaging may be used to improve diagnosis of breast cancer in patients with mammographically dense breasts or silicone implants/injections and to stage disease in patients who are candidates for lumpectomy.

Fat-suppressed three-dimensional MR imaging of the breast

Rotating delivery of excitation off-resonance (RODEO) is a new magnetic resonance (MR) imaging pulse sequence that uses a jump return sine excitation on fat resonance to produce fat-suppressed, T1-weighted images. New three-dimensional MR imaging techniques were used to examine 57 women with abnormalities suspicious for breast cancer. MR imaging findings were compared with those of mammography in all cases and with those of other imaging techniques when appropriate. Thirty-five specimens obtained at mastectomy were analyzed with rigorous pathologic examination that included imaging of the entire breast at 5-mm incremental sections. Histologic confirmation was obtained in 76 lesions in 47 patients. MR imaging helped detect 100% of malignant lesions, whereas mammography produced 33% false-negative findings. The use of RODEO in breast imaging is in the early investigational phases, but it has potential for supplementing mammography in the diagnosis of breast cancer.

MR imaging of the breast

The current strategy for breast cancer treatment involves early detection of the neoplasm before it has metastasized outside the breast, and surgical treatment of the lesion that minimizes deformity. Conventional methods of diagnostic imaging of the breast, including mammography, sonography, and galactography, do not adequately address clinical needs with regard to lesion characterization and staging. Magnetic resonance (MR) imaging has been proposed as a modality that may address these needs. The potential clinical uses of MR imaging are defined in terms of clinical needs and technologic requirements. Applications of MR imaging in detection of breast lesions can be divided into two major approaches based on the clinical questions to be answered: (a) improved specificity and (b) improved sensitivity. These approaches are defined by specific sets of clinical needs and have substantially different technologic requirements. The specificity approach is used to reduce the number of biopsies performed to confirm false-positive mammographic findings. The MR imaging device that is used to improve specificity must visualize only the lesions that are seen mammographically. The sensitivity approach requires the visualization of lesions not identified at mammography, so that breast disease can be more effectively staged for treatment. The technologic requirements for the sensitivity approach are considerably more rigorous because all lesions must be identified. The advantages and disadvantages of each of these approaches and the potential clinical ramifications are described.

Multicenter trial of gadoteridol, a nonionic gadolinium chelate, in patients with suspected head and neck pathology

PURPOSE

To evaluate the safety and efficacy of gadoteridol as an MR contrast agent in patients with suspected head and neck pathology.

METHODS

One hundred thirty-three adult patients were studied with MR at 12 clinical trial sites before and after the intravenous administration of 0.10 mmol/kg gadoteridol. After enrollment, patients underwent a complete physical examination. Patient monitoring included vital signs, laboratory tests, and recording of the incidence and duration of adverse events. To evaluate efficacy, postcontrast T1-weighted images were compared with precontrast T1- and T2-weighted images. Investigators having clinical information evaluated 129 studies for efficacy; two readers blinded to clinical information subsequently evaluated 122 studies using the same criteria as the investigators.

RESULTS

Eight patients (6.0%) experienced mild adverse events possibly or probably related to contrast administration, all of which resolved without treatment. Two clinically significant laboratory abnormalities considered related or possibly related to the administration of gadoteridol were reported in two patients. Enhancement of pathology was seen in 82.9% of cases evaluated by investigators at the study site and in 78.7% of cases subsequently evaluated by the blinded readers. Postcontrast images were judged by investigators to provide additional diagnostic information over precontrast images in 68.9% of studies. The additional diagnostic information available on postcontrast studies most often consisted of improved visualization of pathology and better definition of lesion borders. The use of this information might have contributed to a change in patient diagnosis in 18.6% of the cases evaluated by the investigators and in 16.4% of the cases reviewed by the blinded readers.

CONCLUSIONS

Preliminary results show gadoteridol to be a safe and efficacious contrast agent for enhanced MR study of extracranial and extraspinal head and neck pathology.

Magnetic resonance angiography. Application to the peripheral circulation

Magnetic resonance angiography (MRA) for application in the musculoskeletal system is progressing at a rapid pace. The clinical role of this new technique is still being developed, although a number of uses have already become well recognized, and MRA is diffusing into clinical practice. This article describes the basic fundamentals of MRA as it applies to the peripheral circulation and to the evaluation of potential clinical procedures.

Magnetic resonance imaging of the breast

The diagnosis and treatment of breast cancer is dependent upon accurate depiction of the disease by diagnostic imaging. In a number of clinical situations, conventional breast imaging does not adequately address these diagnostic needs. New magnetic resonance imaging (MRI) methods developed specifically for breast diagnosis may provide the additional capability needed to fill the gap between clinical needs and the information obtained by conventional breast imaging methods. Fat-suppressed 3D MRI has demonstrated improved sensitivity over routine breast imaging methods. MRI can also be used to differentiate between certain benign but mammographically suspicious lesions and cancer. The potential clinical roles of MRI are reviewed with clinical examples. Pitfalls in the use of MRI are defined. The problems encountered with the implementation of MRI in a clinical setting are outlined and future advances predicted.

Magnetization transfer contrast in fat-suppressed steady-state three-dimensional MR images

We demonstrate that magnetization transfer contrast can be used to improve the diagnostic utility of fat-suppressed steady-state three-dimensional gradient-recalled images. Fat suppression is achieved using a "jump-return" pair of contiguous shaped pulses. No time interval exists between the pulses, and no RF echo is generated. The sequence normally produces images with "density" weighting. Preparation of the spin magnetization with off-resonance frequency-selective excitation creates magnetization transfer contrast which attenuates signal intensity in proportion to the exchange rate of magnetization from free water with magnetization from water bound to macromolecules or protons that have restricted mobility. The resulting images have excellent fat suppression with low sensitivity to motion since no subtraction is used. In addition, the mechanism of signal attenuation is independent of paramagnetic effects, and addition of Gd-DTPA produces signal enhancement from vascularized regions of tissue. Examples are presented for the knee and breast, where the observation of pathology with signal enhancement from Gd-DTPA is improved over conventional 3D fat-suppressed images.

Changes in signs and symptoms following temporomandibular joint disc repositioning surgery

Fifty-one subjects with documented intra-articular pathology refractory to non-surgical therapy underwent temporomandibular joint (TMJ) disc repositioning surgery. Following surgery, subjects were evaluated for 6 months to 6 years by clinical examinations and questionnaires at designated times, and by postsurgical joint imaging. Significant decreases were noted in pain (headache, TMJ pain, ear pain, and neck/shoulder pain), the incidence of joint sounds and locking, and the presence of dietary restrictions. However, 35% of the subjects continued to have residual TMJ pain, and a similar percentage continued to need periodic nonsteroidal anti-inflammatory drugs for analgesia. Some degree of dietary restriction remained in approximately 50% of the subjects, and joint sounds persisted in a similar percentage following surgery. Mean mouth opening was improved by 8 mm, although lateral movements were increased by less than 0.5 mm. Surgery did not decrease the occurrence of jaw deviation, and disc position was unchanged in 86% of the joints imaged at an average of 2 years following surgery. Although TMJ disc repositioning surgery significantly improved pain and dysfunction in TMJ surgery patients, the improvement in disc position was not maintained in most subjects following surgery.

Clinical safety and efficacy of gadoteridol: a study in 411 patients with suspected intracranial and spinal disease

In this phase III study, 411 adult patients with suspected intracranial or spinal disease underwent magnetic resonance (MR) imaging before and after intravenous injection of 0.1 mmol/kg gadoteridol (gadolinium 1,4,7-tris [carboxymethyl]-10-[2'-hydroxypropyl]-1,4,7,10-tetraazacyclododecane+ ++). MR images were evaluated by a single unblinded reader at each of 27 sites; the diagnosis was confirmed with one of nine imaging or surgical procedures within 8 weeks before or after MR imaging. After injection, no clinically significant changes were noted in laboratory values, physical examination, or vital signs. Adverse clinical events possibly or probably associated with injection of gadoteridol were seen in 18 of 411 patients (4.4%); the most common were dysgeusia and mild nausea, and all abated without residual effects. MR images enhanced with gadoteridol in patients with confirmed disease provided more diagnostic information than unenhanced images in 128 of 175 brain examinations (73.1%) and 93 of 137 spinal examinations (67.9%). A change in diagnosis because of additional information from contrast-enhanced images was considered likely in 63 of 214 cranial and 54 of 161 spinal studies.

Three-dimensional gadolinium-enhanced MR imaging of the breast: pulse sequence with fat suppression and magnetization transfer contrast. Work in progress

A pulse sequence with magnetization transfer contrast and fat suppression was used in three-dimensional magnetic resonance imaging of the breast. Two healthy volunteers, one person with silicone implants, and 12 patients with clinical and/or mammographic findings suspicious for malignancy were evaluated prior to and following infusion of gadopentetate dimeglumine. Imaging time was approximately 7 minutes for each set of data (128 sections). Final voxel dimensions ranged from 1.4 x 0.8 x 0.8 mm to 1.6 x 0.9 x 0.9 mm. All carcinomas, including ductal and lobular types, were enhanced before and after infusion of contrast medium. Multifocal carcinoma and inflammatory carcinoma could be clearly visualized. Enhancement was not evident in patients with fat necrosis (n = 1) or scar (n = 1). Fibrocystic changes in one patient were visible as areas of increased signal intensity on preinfusion images. Resolution and contrast of MR images obtained with this pulse sequence appeared to be improved over that achieved with conventional breast MR imaging techniques. This method has the potential to supplement conventional diagnostic methods in the evaluation of breast disease.

Success of temporomandibular joint arthroscopy in disk displacement with and without reduction

Forty-three subjects with disk displacement without reduction (DNR) or disk displacement with reduction (DWR) underwent arthroscopic lysis and lavage of the temporomandibular joints. Both groups of subjects were assessed by clinical examination, a questionnaire, and joint imaging, to determine the impact of internal derangement type (DWR vs DNR) on postsurgical outcome. There were no significant differences in postsurgical outcomes between the two groups of meniscal disorders with respect to clinical and questionnaire data. However, the DNR group generally exhibited a smoother, less erratic recovery. After surgery dramatic improvements were in range of motion, pain, and function in both groups, although some level of residual pain and dietary limitation remained in approximately half the subjects. The incidence of joint sounds and deviation were not improved by surgery. Significant differences were found between the two groups with respect to imaging results. Arthroscopy had little effect on the disk positions of DNR subjects: 84% were unchanged after surgery, and the remaining 16% were improved. The disk position of DWR subjects appeared more labile, with 31% unchanged, 38% worsened, and 31% improved.

New method for fast MR imaging of the knee

Thirty-five patients with suspected internal derangements of the knee were examined with conventional two-dimensional (2D) spin-echo magnetic resonance (MR) imaging techniques and a new rapid three-dimensional (3D) method called 3D FASTER (field echo acquisition with a short repetition time and echo reduction). A 9-minute 3D FASTER data acquisition achieves nearly isotropic voxels for the calculation of any desired image plane without a significant loss in image quality. Image contrast is optimized for visualization of knee anatomy in a single sequence. An image-processing workstation is used to speed the multiplanar image calculation and display for more efficient analysis of the complex 3D data set. The 3D FASTER images were superior or equal to 2D images (which took three times longer to acquire) in demonstrating meniscal tears, ligament tears, bone marrow disease, and osteochondral defects. The combined advantages of improved imaging capability and efficiency could make 3D FASTER imaging a routine MR method for knee imaging.

Arthroscopic TMJ surgery: effects on signs, symptoms, and disc position

Nineteen subjects with documented intra-articular pathology refractory to nonsurgical therapies underwent temporomandibular joint (TMJ) arthroscopy involving lysis and lavage in the superior joint space. Following surgery, subjects were evaluated for 6 to 12 months by clinical examinations and questionnaires at designated time periods and by postsurgical joint imaging. Significant improvement was noted in pain, mandibular movement, and diet. No improvement was noted in the incidence of joint sounds, and disc position was unchanged in 80% of the joints. The findings suggest that disc repositioning may not be needed to achieve clinical success.

MR imaging of pseudoaneurysms in aortocoronary bypass graft

Aneurysm formation may complicate aortocoronary saphenous vein bypass grafts. Because of multiplanar imaging capabilities and the potential for flow evaluation, magnetic resonance (MR) is useful as a noninvasive diagnostic technique. Two cases of pseudoaneurysm formation were evaluated by MR and demonstrate the clinical value of this modality.

MR evaluation of giant cell tumors of the tendon sheath

Giant cell tumor of the tendon sheath (GCTTS) is a benign condition that involves the synovium of the tendon sheaths. Histologically, GCTTS is similar to pigmented villonodular synovitis. The MRI findings in two cases of GCTTS are reported. In both cases, predominantly low signal is seen on T1-weighted, proton density weighted, and T2-weighted images. This information may be useful in distinguishing GCTTS from other mass lesions involving the tendon sheaths.