Dynamic Gd-DTPA Research Articles

Dynamic MR tomography in the diagnosis of inflammatory and tumorous space-occupying lesions of the musculoskeletal system

In 216 inflammatory and tumorous lesions of bone and soft tissue, dynamic Gd-DTPA enhanced MR imaging was performed. For that purpose, 12 FLASH sequences (TR = 40 ms/TE = 10 ms/NSA = 2/flip angle = 90 degrees) were acquired within 4 minutes; and Gd-DTPA bolus injection was administered following the first sequence. Slopes from the signal intensity curves were calculated. Estimated slopes allowed an assessment of the malignant potential of a lesion with an accuracy of 88%. Further more, a reliable differentiation between vital and necrotic tissue and between tumour and peritumoral edema was reliably possible. With this technique, response of malignant tumours to preoperative chemotherapy was correctly predicted in 83% of the cases. No differentiation of inflammatory from tumorous lesions was possible.

Response of osteosarcoma and Ewing sarcoma to preoperative chemotherapy: assessment with dynamic and static MR imaging and skeletal scintigraphy.

In 15 osteosarcomas and six Ewing sarcomas, response to preoperative chemotherapy was assessed with magnetic resonance (MR) imaging without and with gadolinium diethylenetriaminepentaacetic acid (DTPA) enhancement and with dynamic Gd-DTPA studies, and the results were compared with the scintigraphic findings. All studies were obtained prior to and following preoperative chemotherapy. Static MR imaging was of little value for assessment of response; reduction in signal intensity within soft-tissue masses on the T2-weighted spin-echo images indicated response with a sufficient degree of accuracy (71%) but low sensitivity, whereas an increase in signal intensity after Gd-DTPA administration indicated zones of viable tissue with low specificity. With three-phase skeletal scintigraphy, the findings in the perfusion and blood-pool phases were of no value, whereas the findings in the osseous phase allowed the prediction of response with an accuracy of 73.7%. Of all techniques employed, dynamic MR imaging had the highest degree of accuracy (85.7%) and was superior to scintigraphy, particularly in patients who were receiving intraarterial chemotherapy.

Nasal Orientation Device to Control Head Movement during CT and MR Studies

Cooperative patients can often keep still during a long examination of the brain provided that they are given cues about their position in space. In a U-shaped head support, the only movements likely are rotation in the sagittal or transverse planes. These can be detected by a nasal orientation device (NOD), simply a ring around the nose, close but not touching. Any unintentional movement is felt on the nose by the patient, who can return to the original (nontouching) position. With this device the patient can keep immobile to within approximately +/- 2 mm during long examinations. We have used the NOD to improve the quality of dynamic Gd-DTPA scanning for the measurement of blood-brain barrier permeability. The NOD can be of value in any neurological imaging procedure that is currently degraded by head movement.

Musculoskeletal neoplasms: static and dynamic Gd-DTPA--enhanced MR imaging.

Static and dynamic magnetic resonance imaging studies were performed in 69 patients with bone and soft-tissue tumors. T1-weighted spin-echo (SE) imaging after intravenous administration of gadolinium diethylenetriaminepentaacetic acid (DTPA) improved the differentiation of necrotic from viable areas; the contrast-to-noise ratio (C/N) between tumor and muscle was an average of 44% lower compared with that in T2-weighted SE imaging. The C/N between tumor and bone marrow or fatty tissue was 43% and 37% lower, respectively, compared with that in nonenhanced T1-weighted SE imaging. Dynamic changes of signal intensity (SI) after Gd-DTPA enhancement were assessed with fast low-angle shot imaging. Of malignant tumors, 84.1% exhibited slopes higher than 30% per minute; 72% of benign tumors showed slopes lower than 30% per minute. The dynamic technique enabled assessment of the malignant potential of a tumor with some overlap (accuracy, 79.7%). Necrotic areas and peritumorous edema showed significantly lower and more gradual increases in SI than adjacent neoplastic tissue.