Abdominal vessel enhancement with an ultrasmall, superparamagnetic iron oxide blood pool agent: evaluation of dose and echo time dependence at different field strengths.

RATIONALE AND OBJECTIVES: The purpose of the study was to determine the dose and echo time dependence of abdominal vessel enhancement at magnetic resonance (MR) imaging after injection of a blood pool contrast agent at two field strengths. MATERIALS AND METHODS: Sixteen healthy volunteers received NC100150 Injection at three dose levels (1.0 mg, 2.5 mg, and 4.0 mg of iron per kilogram of body weight). Images of the aorta and inferior vena cava (IVC) were obtained at 0.5 or 1.5 T. Four sequences with varying echo times were used with each subject. Signal intensities were recorded from the aorta, IVC, vessel vicinity, air, and a marker outside the patient. Contrast-to-noise ratios (CNRs) were calculated for the vessels. Aortic delineation was subjectively evaluated. RESULTS: Images with the highest mean vessel signal intensities, subjectively assessed as satisfactory for aortic delineation, were obtained with 2.5-4.0 mg of iron per kilogram of body weight at both field strengths. The highest CNR was found with 4.0 mg of iron per kilogram of body weight at 1.5 T. An increase in echo time caused larger signal intensity loss at larger dose levels. The signal intensity from the IVC was higher than that of the aorta at all dose levels, echo times, and field strengths. CONCLUSION: NC100150 Injection is an efficient T1-reducing agent at both 0.5 and 1.5 T. A positive dose response for CNR of the aorta and IVC was seen at 1.5 T.

CT-guided bone biopsy performed by means of a coaxial biopsy system with an eccentric drill.

Thirty-seven consecutive bone biopsies guided with computed tomography were performed in 32 patients by use of three different techniques to penetrate cortical bone and gain access to the lesion. The following instruments were used: a thin bone biopsy needle (12 biopsies), a conventional drill with an outer cannula (six biopsies), and a coaxial biopsy system that consists of a drill with an eccentric tip and an outer cannula (19 biopsies). This eccentric drill makes a hole in the bone larger than the diameter of the cannula and thereby makes it easy to advance the cannula over the drill until the cannula is anchored in the bone. One can then obtain multiple samples through the cannula. The thin bone biopsy needle could not penetrate thick (8 mm thick) cortical bone. The outer cannula was not anchored in the bone when the conventional drill was used. In 16 biopsies, the new coaxial biopsy system penetrated cortical bone with a thickness of 1-8 mm and was anchored there, and lesion samples were obtained through the anchored cannula.

CT-guided transsternal core biopsy of anterior mediastinal masses.

Computed tomography-guided transsternal biopsy was successful in 10 anterior mediastinal masses in 10 patients, with use of a coaxial length-matched bone biopsy system comprising an outer cannula and an inner eccentric drill bit. No complications occurred in nine of 10 biopsies (eight performed with an automatic cutting needle, two with a fine needle), with less discomfort than was caused by injection of anesthetic.

Automatic biopsy instruments used through a coaxial bone biopsy system with an eccentric drill tip.

Twenty-eight consecutive CT (n = 23) or ultrasonographically (n = 5) guided biopsy procedures were performed on musculoskeletal lytic lesions covered (n = 13) or not covered (n = 15) with intact bone. Specimens were obtained by means of Biopty techniques (n = 27), i.e. Biopty and Monopty instruments, through different cannulas with normal or shortened needle-throws. Four out of 5 bone penetrations were successful with an Ostycut needle, and all 8 bone penetrations by a coaxial bone biopsy system with an eccentric drill. The eccentric drill makes a hole in the cortical bone larger than the diameter of the outer cannula of this system, making it easy to anchor the cannula and then coaxially insert a Biopty-Gun needle for example. The overall histopathological diagnostic accuracy of the Biopty techniques was 25/27 (92.6%).

Early response of breast cancer bone metastases to chemotherapy evaluated with MR imaging.

PURPOSE: To compare T1-weighted spin-echo and fat-suppressed long echo time inversion recovery turbo spin-echo (long TE IR-TSE) MR images in the evaluation of early response of breast cancer bone metastases to chemotherapy. MATERIAL AND METHODS: Eighteen breast cancer patients with known bone metastases were investigated prospectively by MR, using T1-weighted and long TE IR-TSE sequences on the sternum, spine, pelvis and proximal femora, before and after a median of 6 courses of chemotherapy. Therapeutic response evaluation with MR was based on change in tumor size assessed quantitatively by measuring all focal metastases, and change in pattern and signal intensity (SI) of the metastases, assessed visually. Combined response evaluation based on clinical findings, conventional radiography, and scintigraphy was used as reference. RESULTS: Progressive disease (2 patients) and no change (4 patients) were assessed equally well on both MR sequences. Long TE IR-TSE demonstrated partial response with higher accuracy than T1-weighted images, 58% (7/12 patients) vs. 17% (2/12 patients). In patients without progression there was an SI increase in or around the metastases in 6 patients on T1-weighted images and in 7 patients on long TE IR-TSE images. CONCLUSION: The long TE IR-TSE sequence demonstrated early partial response of breast cancer bone metastases to chemotherapy more accurately than the T1-weighted sequence.

MR imaging of primary, secondary, and mixed forms of lymphedema.

PURPOSE: To describe the pathological features and assess the diagnostic information of different MR sequences in patients with primary, secondary, and mixed (phlebo-, lipophlebo-, or lipolymphedema) forms of lymphedema of the lower leg. MATERIAL AND METHODS: In 26 patients with clinical diagnoses of primary (n=10), pure secondary (n=4), mixed (n=9) and combined secondary and mixed forms of lymphedema (n=3), MR imaging was performed with coronal and axial T1 SE, T2 TSE, fat-suppressed (SPIR) T2 sequences and axial T1 SE after i.v. injection of Gd-DTPA. RESULTS: In 24 patients there was a honeycomb pattern in the subcutis with a signal intensity corresponding to fluid (n=11), fibrosis (n=3), or both (n=10). Five patients with primary lymphedema showed subfascial fluid accumulation. Dermal edema was noted in 23 patients. Fat or edema components in the muscles were mostly seen in patients with phlebolymphedema. The honeycomb pattern was best seen on coronal T1 images, and fluid accumulations on axial SPIR-T2 images. Fibrosis was only assessible from the T2 TSE sequence. Gd-DTPA did not improve the diagnostic information. CONCLUSION: For evaluation of lymphedema and its mixed forms, an axial T2-weighted SPIR sequence in conjunction with a coronal T1 SE sequence are sufficient.

Pulmonary MR angiography with ultrasmall superparamagnetic iron oxide particles as a blood pool agent and a navigator echo for respiratory gating: pilot study.

In nine healthy adult volunteers, pulmonary magnetic resonance angiography was performed with the blood pool agent NC100150 injection combined with respiratory gating with a navigator echo. With increasing doses of the contrast agent, higher signal intensities and vessel branch order visualization were achieved. No motion artifacts were seen. The blood pool agent NC100150 injection in combination with respiratory navigator gating permitted acquisition of high-quality MR angiograms of the pulmonary vasculature during continuous breathing.