Gadolinium-DTPA enhancement of soft tissue tumors in magnetic resonance imaging--preliminary clinical experience in five patients

Gadolinium-Dtpa Enhancement of Soft Tissue Tumors in Magnetic Resonance Imaging

In a clinical study of 13 patients, gadolinium-DTPA (Gd-DTPA) was used for enhancement of soft tissue tumors at magnetic resonance imaging. Gd-enhanced T1 sequences were found to give additional information concerning tumor vascularity in 11 cases, tumor necrosis in 2 cases and tumor delineation in one case, compared with conventional T1 and T2 weighted spin echo sequences. If Gd-enhanced sequences were to be used as the only source of information, accurate assessment of tissue composition of the tumor would not have been possible. Furthermore, valuable information regarding tumor delineation towards surrounding fat may be lost.

Static, Dynamic and First-Pass MR Imaging of Musculoskeletal Lesions Using Gadodiamide Injection

Forty-five patients with known or suspected musculoskeletal tumors were examined with static and dynamic MR imaging to evaluate the safety, tolerability and diagnostic utility of gadodiamide injection and to assess the diagnostic value of dynamic MR imaging and parametric “first-pass” (FP) images. The proportion of patients presenting more diagnostic information on the contrast-enhanced compared to the precontrast spin-echo examinations was determined. The dynamic enhancement characteristics were evaluated with time-intensity curves and parametric images of the FP enhancement rate. The tolerance of gadodiamide injection was good. Contrast enhancement was useful for delineating tumor from muscle, and differentiating viable from necrotic tissue and cystic from solid lesions. Malignant tumors showed a significantly higher slope value, earlier onset of enhancement, and higher maximum enhancement than benign lesions. However, slope values could not be used to predict the malignant potential of a lesion, due to overlap between highly vascular benign and low vascular malignant lesions. By displaying highly vascular areas, parametric FP images provided useful information on the most active part in a tumor before biopsy and for assessing the incorporation of bone-chip allografts. Static, dynamic and FP MR imaging using gadodiamide injection appears safe and provides useful information for diagnosis, biopsy and follow-up of musculoskeletal lesions.

Magnetic resonance imaging (MRI) contrast agents for tumor diagnosis

This review focuses on MRI contrast agents for tumor diagnosis. Several types of low molecular weight Gd3+-based complexes and dextran-coated superparamagnetic iron oxide (SPIO) nanoparticles have been used for clinical tumor diagnosis as longitudinal relaxation time (T1) and transverse relaxation time (T2) MRI contrast agents, respectively. To further improve the sensitivity of MRI, new types of chelates for T1 MRI contrast agents and combination of low molecular weight T1 MRI contrast agents with different types of carriers have been investigated. Different types of materials for forming secure coating layers of SPIO and novel superparamagnetic particles with higher relaxivity values have been explored. Various types of ligands were applied to improve the capability to target tumor for both T1 and T2 contrast agents. Furthermore, MRI contrast agents for detection of tumor metabolism were also pursued.

Soft-Tissue Tumors: Value of Static and Dynamic Gadopentetate Dimeglumine–enhanced MR Imaging in Prediction of Malignancy

PURPOSE

To prospectively evaluate static and dynamic gadopentetate dimeglumine-enhanced magnetic resonance (MR) imaging relative to nonenhanced MR imaging in differentiation of benign from malignant soft-tissue lesions and to evaluate which MR imaging parameters are most predictive of malignancy, with associated interobserver variability.

MATERIALS AND METHODS

One hundred forty consecutive patients (78 male patients [median age, 51 years], 62 female patients [median age, 53 years]) with a soft-tissue mass underwent nonenhanced static and dynamic contrast material-enhanced MR imaging. Diagnosis was based on histologic findings in surgical specimens (86 of 140), findings at core-needle biopsy (43 of 140), or results of all imaging procedures with clinical follow-up (11 of 140). Multivariate logistic regression analysis was used to identify the best combination of MR imaging parameters that might be predictive of malignancy. Subjective overall performance of two observers was evaluated with receiver operating characteristic analysis.

RESULTS

For subjective overall diagnosis, area under the receiver operating characteristic curve, a measure for diagnostic accuracy, was significantly larger for combined nonenhanced and contrast-enhanced MR imaging than it was for nonenhanced MR imaging alone, with no significant difference between observers. Multivariate analysis of all lesions revealed that combined nonenhanced static and dynamic contrast-enhanced MR imaging parameters were significantly superior to nonenhanced MR imaging parameters alone and to nonenhanced MR imaging parameters combined with static contrast-enhanced MR imaging parameters in prediction of malignancy. The most discriminating parameters were presence of liquefaction, start of dynamic enhancement (time interval between start of arterial and tumor enhancement), and lesion size (diameter). Results for extremity lesions were the same, with one exception: With dynamic contrast-enhanced MR imaging parameters, diagnostic performance of one observer did not improve.

CONCLUSION

Static and dynamic contrast-enhanced MR imaging, when added to nonenhanced MR imaging, improved differentiation between benign and malignant soft-tissue lesions.

Iliacus hematoma and femoral nerve palsy after revision hip arthroplasty: a case report

Femoral nerve palsy occurred in a 65-year-old man after he had undergone a revision total hip arthroplasty using cementless components. The magnetic resonance imaging scan showed a mass in the iliacus muscle. The mass showed increased signal intensity on T1-weighted and T2-weighted spin-echo images and contained linear septa and a nodule. The gadolinium-enhanced T1-weighted image showed a rim of significant enhancement in the nodule. The findings of magnetic resonance images were suggestive of iliacus hematoma and of liposarcoma. The patient underwent surgery, and the mass was identified as an iliacus hematoma. The femoral nerve was stretched by the hematoma. After removal of the hematoma, the nerve palsy was improved completely. Iliacus hematoma may occur after total hip arthroplasty, even without anticoagulant therapy. The hematoma might appear to be a liposarcoma on magnetic resonance imaging scans.

Iliopsoas bursa of the rheumatoid hip joint. A case report and review of the literature

Presented is the case of a 63-year-old woman, with a 30-year history of rheumatoid arthritis, whose hip was completely destroyed and accompanied with enlargement of the iliopsoas bursa. Preoperative diagnosis was confirmed by computed tomography, magnetic resonance (MR) imaging and arthrography. She was treated by resection of the iliopsoas bursa and total prosthetic replacement of the hip joint. The pathogenesis is uncertain. In the literature, enlargement of the iliopsoas bursa with rheumatoid arthritis, osteoarthritis, pigmented villonodular synovitis, and synovial chondromatosis had been reported. Nevertheless, a correct preoperative diagnosis of the enlargement of the iliopsoas bursa is very difficult. MR imaging with enhanced Gadolinium-DTPA (Gd-DTPA) is proposed as the most useful examination for preoperative diagnosis.

Magnetic resonance imaging of musculoskeletal tumors

In summary, MRI is the preferred modality for the evaluation of a soft-tissue mass following radiography. The radiologic appearance of certain soft-tissue tumors or tumor-like processes such as benign fatty tumors, intramuscular hemangiomas, pigmented villonodular synovitis, and certain hematomas may be sufficiently unique to allow a strong presumptive radiologic diagnosis. It must be emphasized that MRI cannot reliably distinguish between benign and malignant lesions and, when radiologic evaluation is nonspecific, one is ill advised to suggest a lesion is benign or malignant solely on its MR appearance. The role of MRI in the evaluation of bone tumors is predominantly one of staging. MRI is superb to evaluate the extent of intraosseous and soft-tissue involvement as well as the relationship of the lesion to the neurovascular bundle. Unfortunately, MRI remains nonspecific and is unable to predict lesion histology. Finally, the value of Gd-DTPA enhanced imaging is still to be determined.

MR imaging of soft-tissue masses: role of gadopentetate dimeglumine

To assess the effectiveness of gadopentetate dimeglumine in the magnetic resonance (MR) imaging evaluation of soft-tissue masses without osseous involvement, 30 patients underwent MR imaging before and after administration of contrast material (0.1 mmol/kg). Of the 30 lesions, 22 were benign and eight were malignant; histologic confirmation was available in all lesions except one benign lesion. Overall, enhancement was detected in 26 (87%) of 30 lesions: 18 (82%) of the 22 benign lesions and eight (100%) of eight malignant lesions. Enhancement was characterized as homogeneous (two [11%] benign lesions, two [25%] malignant lesions), inhomogeneous (11 [61%] benign lesions, six [75%] malignant lesions), or peripheral (five [28%] benign lesions, no malignant lesions). Of the 19 lesions assessed for a change in enhancement over time, seven (37%) showed an increase and two (11%) showed a decrease in signal intensity. The authors conclude that benign and malignant soft-tissue lesions could not be differentiated solely on the basis of enhancement (pattern, degree, or time course).

MRI of malignant "triton" tumor in a child

We report a case of malignant "Triton" tumor of the right foot in a 5-year-old Caucasian boy with neurofibromatosis. The characteristics and the extent of the tumor were well demonstrated on magnetic resonance imaging.

Diagnostic value of gadopentetate dimeglumine for 1.5-T MR imaging of musculoskeletal masses: comparison with unenhanced T1- and T2-weighted imaging

Three magnetic resonance (MR) imaging techniques (T1-weighted, T2-weighted, and T1-weighted gadopentetate dimeglumine--enhanced) were compared in 32 consecutive MR imaging studies of 26 patients with suspected musculoskeletal masses. T2-weighted images were superior to T1-weighted enhanced images with respect to detection and definition of lesions in 12% of cases (n = 4) and were equal in 88% of cases (n = 28). T2-weighted images were also superior to T1-weighted images in 38% of cases (n = 12). In no cases were T1-weighted enhanced images superior to T2-weighted images. In two cases, T1-weighted images were superior to both T1-weighted enhanced and T2-weighted images. The authors conclude that gadopentetate dimeglumine did not provide much value in lesion detection above that obtained with T2-weighted images. They also conclude that T1-weighted images were occasionally superior to T1-weighted enhanced images and T2-weighted images because of loss of definition between fat and lesion on the latter.

Magnetic resonance imaging of musculoaponeurotic fibromatosis

Musculoaponeurotic fibromatosis can be mistaken for soft-tissue sarcoma both clinically and on X-ray computed tomography. Magnetic resonance imaging (MRI) in three patients with this condition enabled the correct diagnosis to be made prospectively in two. The appearance on MRI of a heterogeneous mass with well-defined, predominantly peripheral areas of very low signal intensity due to dense fibrous tissue and areas of medium to high signal intensity corresponding to a more cellular stroma should raise the the suspicion of musculoaponeurotic fibromatosis. Cellular areas within the tumour showed moderate enhancement after gadolinium diethylene triamine pentaacetic acid administration.