Gadopentetate dimeglumine and iodinated contrast media. Hemodynamic side effects after bolus injections in pigs.

RATIONALE AND OBJECTIVES: The use of bolus injections of contrast media containing gadolinium for magnetic resonance imaging and their potential use as x-ray absorbents require the evaluation of possible cardiovascular side effects. The hemodynamic reactions of high doses (0.6 mmol/ kg) of gadopentetate dimeglumine (gadolinium [Gd]-DTPA, Magnevist) were evaluated and compared with the side effects of ionic (diatrizoate: Urografin 76%) and nonionic (iopamidol, Solutrast 370) radiographic contrast media. METHODS: In 18 pigs, pressure and flow of the systemic and pulmonary circulation were monitored after intracardiac bolus injections (2-4 seconds) of dose volumes of 1.2 mL/kg of each contrast agent. RESULTS: All contrast media decreased the aortic pressure transiently (Gd-DTPA and diatrizoate: -25%, iopamidol: -10%; P < 0.01). Pulmonary artery pressure, cardiac output, and stroke volume increased for several minutes. The vascular resistance declined. Diatrizoate induced stronger and longer-lasting side effects (P < 0.01) than Gd-DTPA and iopamidol. CONCLUSIONS: Despite of similar osmolality, Gd-DTPA induced weaker side effects than equivolumetric applications of diatrizoate. Other than osmolality, other factors such as viscosity and chemotoxicity influence the side effects of contrast media.

[Magnetic resonance tomography in the diagnosis of mandibular osteomyelitis]. / Magnetresonanztomographie zur Diagnostik von Unterkieferosteomyelitiden.

PURPOSE: A prospective study of the value of MRI in the diagnosis of osteomyelitis of the mandible with special reference to the suitability of different MR sequences. MATERIAL AND METHODS: In 13 patients, average age 55 years (12-82), with clinical suspicion of osteomyelitis of the mandible, 18 MRI examinations were carried out (STIR, TSE T2, proton and SE T1 weighted scans with and without contrast, slice thickness 3.5 to 6 mm). Image quality of the sequences was evaluated as well as the suitability of the various sequences for showing the lesion, its location and extent. Activity of the osteomyelitis was judged by the degree of contrast uptake and was correlated with 3-phase bone scintigraphy and with histological findings. RESULTS: In 9 of the 14 cases the findings on MRI and of the scintigraphy agreed with the histology. In two patients the activity of the inflammatory process was exaggerated by the MRI. In another follow-up examination it was slightly underestimated. All lesions were shown to be highly active by the histology were recognized as such by MRI. For the localisation and recognition of the extent of the inflammatory processes STIR sequences and T1 weighted non-enhanced SE sequences proved the most suitable. Contrast medium is essential to evaluate the inflammatory activity. CONCLUSION: MRI is a sensitive diagnostic method; it is as good as 3-phase bone scintigraphy in demonstrating osteomyelitis of the mandible and of its activity but is superior for showing the pathological anatomy.

[Magnetic resonance imaging vs. three-dimensional scintigraphy in the diagnosis and monitoring of mandibular osteomyelitis]. / Magnetresonanztomographie (MRT) vs. 3-Phasen-Skelettszintigraphie bei der Diagnostik und Verlaufskontrolle der Unterkieferosteomyelitis.

Bone scintigraphy is routinely used in the diagnosis of lower jaw osteomyelitis; however, the radiation dosage of 3.5 mSv is quite high. Magnetic resonance imaging (MRI) gives information about soft tissue and bone marrow alterations. This study compares the sensitivity of the two imaging modalities in the diagnosis of lower jaw osteomyelitis. Thirteen patients with clinical signs of the disease were examined and followed up using both methods, three-phase bone scintigraphy and MRI. Compared to three-phase bone scintigraphy, MRI has the same diagnostic sensitivity. However in one case of active osteomyelitis bone scintigraphy showed a false-negative result. MRI once indicated a higher activity rate but never failed to provide the diagnosis. In addition, it gives exact information about the location, size and involvement of the soft tissue. A STIR sequence should be performed in addition to the native and contrast-enhanced T1-weighted spin echo sequence. The metal artifacts of the antibiotic chain on the MRI can be eliminated by replacing the wire by nonresorbent suture material. In the diagnosis of lower jaw osteomyelitis, three-phase bone scintigraphy can be replaced by the MRI.