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To present magnetic resonance (MR) imaging findings from 511 follow-up examinations of aggressive soft-tissue tumors.One hundred eighty-two patients with aggressive soft-tissue tumours underwent postoperative T1- and T2-weighted imaging; 41 also underwent 51 gadolinium-enhanced T1-weighted examinations, and five underwent dynamic gadolinium-enhanced subtraction imaging.Twenty-four of 25 patients (101 of 102 examinations) without high signal intensity (HSI) at T2-weighted imaging had no recurrence. Among 79 patients (321 examinations) who demonstrated HSI without a mass, only two tumors recurred within 1 year. An HSI mass was found in 88 studies of 78 patients and represented recurrence (n = 60), hygroma (n = 24), or a radiation-induced pseudomass (n = 4). Hygromas did not enhance, while recurrences enhanced at 1-3 minutes and postirradiation change enhanced at 4-7 minutes.T2-weighted imaging can be used to identify possible recurrence of aggressive soft-tissue tumors, while gadolinium-enhanced imaging can be used to differentiate recurrences from hygromas and inflammatory change.

Recently, MR angiograms of the carotid and intracranial arteries have shown excellent depiction of these vessels [1, 2J. The angiograms are typically derived by acquiring a threedimensional Fourier transform (3DFT) volumetric data set and then projecting the sections to calculate an angiogramlike image from a given viewing angle. Projections are easier to interpret than are the original multiple sections because tortuous vessels can be traced more readily. In addition, the projection is similar in appearance to that of conventional angiography. When forming projection images, the maximumintensity-projection (MIP) algorithm [3] is used most often, rather than a simple summation of the sections (Fig. 1). The MIP provides superior contrast between high-intensity blood and surrounding low-intensity stationary tissue because it does not sum up the background across the entire projected volume, but rather picks out the maximum intensity voxel encountered in the projected ray. Despite the advantages of MIPs, our preliminary experience with MR angiography is that vascular anatomy is systematically distorted by the unusual contrast behavior of MIPs when many sections are projected. The purpose of this essay is to illustrate these artifacts.

More than 50% of malignant soft tissue tumors recur locally [2, 6]. There are several reasons for these disastrous results. Since benign tumors are 100-fold more frequent than malignant ones [6], the latter are frequently not suspected until after initial surgery, resulting in inadequate margins and microscopic residual nodules. The general surgeon who operates on many benign soft tissue masses takes tremendous precautions to preclude functional sequelae in patients. Most often he attempts to enucleate the lesion, particularly as most malignant tumors look macroscopically well limited, with a pseudocapsule, giving the erroneous impression of being benign. In fact, however, multiple, sometimes small, nonpalpable satellite nodules, often at the periphery of the main mass are discovered only at histologic examination after the operation is over, and these tiny lesions may account for the frequency of local recurrence. The histologic analysis of malignant soft tissue tumors is a formidable task, for more than 50 subgroups have been recognized [6]. In practice, every malignant soft tissue lesion (because of size or location criteria) should be sent to a reference center for evaluation and biopsy.

The excellent soft-tissue contrast and multiplanar imaging capabilities of MR imaging have led to its emergence as the most significant advance in the imaging of musculoskeletal tumors. MR imaging is the modality of choice for local staging, evaluating response to preoperative chemotherapy, and long-term follow-up in bone tumors. MR imaging is the most effective modality for both primary staging of soft-tissue malignancy and detecting recurrences. This article reviews the role of conventional spin echo techniques versus newer techniques, and then discusses the indications in the diagnosis, staging, evaluation of preoperative chemotherapy, and detection of recurrences in bone and soft-tissue tumors.

A new magnetic resonance (MR) technique, gadolinium-enhanced subtraction MR imaging, was developed to evaluate the response of patients with osteosarcoma to chemotherapy. Ten patients, who had received chemotherapy for osteosarcoma of the lower extremity, underwent MR imaging 3 days before surgery. After routine MR imaging was performed, subtraction MR was performed in the plane in which the tumor was best visualized. With gadopentetate dimeglumine (0.1 mmol per kilogram) on a standard MR console, subtraction images were created by subtracting precontrast images from gadolinium-enhanced T1-weighted images. The time of maximal tumoral vascular uptake was 1 1/2 minutes after injection, and, therefore, the subtracted image obtained at this time was used for evaluation of viable tumor. Independently, radiologists and histopathologists examined their respective studies for viable tumor to differentiate responders from nonresponders. Four of 10 osteosarcomas were classified as good responders because they appeared as nonenhancing masses, with or without enhancing thin lines, or small nodules (< or = 3 mm wide). At histopathologic examination, all were good responders with less than 3% viable tumor. Six of 10 osteosarcomas were classified as nonresponders because they appeared as enhancing high-signal-intensity masses measuring more than 3 mm in width. Five tumors had between 18% and 43% viable tumor cells.

The authors present three cases of histologically proved synovial sarcoma. CT is useful in assessing erosive or destructive changes in bone, and in demonstrating calcifications. MR characteristics are nonspecific; calcifications within these tumors can be missed on MR. MR can help to assess tumor extension, vascular invasion, and hemorrhage within the tumor.

Local recurrences of aggressive soft tissue tumors are frequent and very difficult to detect clinically after surgery and radiation therapy. Ultrasound is limited because the skin is thick. On contrast-enhanced CT, both scars and recurrences increase their signal. MRI is the best technique, and the only one we presently use in the detection of recurrent tumors. We are reporting 511 follow-up examinations in 182 patients after tumor removal. All patients had histologic confirmation or at least 6 months follow-up. There were 164 malignant tumors and 18 cases of aggressive fibromatosis.

PURPOSE: To compare magnetic resonance angiography (MRA) with duplex Doppler ultrasound (US) and x-ray angiography (XRA) in the evaluation of the carotid bifurcation. METHODS: The carotid arteries of 61 patients were studied using MRA, US, or XRA; 31 of the patients underwent all three examinations. MRA included both 2D and 3D time-of-flight sequences. Internal and external carotid artery origins were graded normal, mild, moderate, severe, or critical stenosis, or complete occlusion by each of the three studies. RESULTS: Spearman rank correlations of both internal and external carotid artery grades were 0.85 (MRA and XRA), 0.69 (MRA and US), and 0.73 (XRA and US). For internal carotid artery origins only, the correlations were 0.94 (MRA and XRA), 0.85 (MRA and US), and 0.82 (XRA and US). Of discrepancies in internal carotid artery interpretation greater than one grade, seven resulted from US error, three from MRA error, and one from XRA error. A 2-cm partially thrombosed aneurysm detected by US and MRA was missed by XRA. Of 16 possible ulcers on XRA, 11 were noted by MRA, none by US. CONCLUSIONS: MRA and XRA are similar in assessment of carotid bifurcation stenosis. MRA, like US, permits direct visualization of plaque. This preliminary study suggests that MRA may be used to clarify equivocal findings of US, or replace XRA in presurgical planning.

MR images of seven patients with histologically documented mixed mullerian sarcoma were analyzed retrospectively to determine whether the scans showed findings that could suggest the diagnosis. Spin-echo T1- and T2-weighted sagittal and transverse images from either a 0.35- or a 1.5-T unit were available for each patient. MR image analysis included evaluation of tumor signal intensity on T1 and T2 images; tumor location, size, and extent; depth of myometrial invasion; and presence of pelvic metastases. In all seven patients, MR images showed a large endometrial mass deeply invading the myometrium or beyond. In addition, MR images showed intraperitoneal (two patients) and ovarian (one patient) metastases. Although the massiveness of the tumors on initial presentation may suggest the diagnosis of mixed mullerian sarcoma, the MR imaging findings are nonspecific and mimic invasive endometrial carcinoma.

The potential of magnetic resonance (MR) imaging in the detection of endometrial carcinoma and in the assessment of its extent was evaluated prospectively in 51 patients clinically suspected of having the disease. MR imaging findings were compared with the results of surgical-pathologic staging and lymph node sampling following hysterectomy. Histologic findings showed 45 patients to have endometrial carcinoma, three to have no residual tumor after dilatation and curettage, and three to have adenomatous hyperplasia of the endometrium. MR imaging demonstrated an endometrial abnormality in 43 of the 51 patients (84%). Endometrial carcinoma could not be differentiated from adenomatous hyperplasia or blood clots. Therefore, MR imaging was not specific for tumor detection, and histologic diagnosis remains essential. The overall accuracy of MR imaging in staging endometrial carcinoma was 92%; its overall accuracy in demonstrating the depth of myometrial invasion was 82%. Demonstration of lymphadenopathy and adnexal or peritoneal metastases by MR imaging was suboptimal.

Mycosis fungoides is a malignant lymphoma of the skin that causes intense erythema, plaques, edema, and induration. The primary computed tomographic findings of mycosis fungoides, i.e., skin thickening, tumorous infiltration, edema of the soft tissues, and lymphadenopathy, are presented in two patients.