Maria Lönnemark

Effect of Superparamagnetic Particles as Oral Contrast Medium at Magnetic Resonance Imaging a Phase I Clinical Study

Non-biodegradable superparamagnetic particles were used as an oral contrast medium in different concentrations, and evaluated in 25 human volunteers. The aim of the study was to determine the most appropriate concentration of the contrast medium, and to evaluate the effect, distribution, safety and tolerance. With the concentration of 1.0 g/l a substantial reduction of the signal intensity in the bowel was achieved in both T1 and T2 weighted images. The intraabdominal structures were well differentiated from the bowels containing contrast medium. ‘Metal’ artifacts and blurring of adjacent structures, probably due to an increased local concentration, were observed at higher dosages. The distribution of the preparation in the gastrointestinal tract varied between individuals. As a rule a good contrast effect was achieved in the small bowel with the exception of the duodenum. The contrast medium was well accepted and did not cause any side effects of clinical importance. The results suggest that the preparation is well tolerated by humans and may be a useful contrast medium for abdominal MR imaging.

Superparamagnetic Particles as Oral Contrast Medium in MR imaging of Malignant Lymphoma

Non-biodegradable superparamagnetic particles, in plain and viscous aqueous suspensions, were used as an oral contrast medium in 34 patients with known or suspected malignant lymphoma. The contrast effect, the occurrence of artifacts, and the distribution were evaluated in the plain and the viscous aqueous suspensions, and the diagnostic information received from abdominal MR examinations performed without bowel contrast medium was compared with that of post-contrast examinations. Magnetic particles in the concentration of 0.5 g/l displayed a good contrast effect at 0.5 T, and helped in differentiating the intestine from adjacent tissues, resulting in increased diagnostic information in abdominal MR imaging. In the patients given the viscous aqueous suspension the occurrence of artifacts caused by the magnetic particles decreased considerably, and the distribution was homogeneous and improved compared with that in patients given the plain aqueous suspension.

Staging of bladder carcinoma by computer tomography-guided transmural core biopsy

In an attempt to improve staging of bladder cancer, computed tomography-guided transmural core biopsy was performed in 17 patients. In the first four patients a 0.9 mm cutting needle was used. This small needle yielded easily fragmented cores and consequently the remaining biopsies were taken with a 1.2 mm needle with an improved result. In all but one case sufficient histological material to allow a diagnosis was obtained by the core biopsy technique. Transmural tumor infiltration, as verified in corresponding cystectomy specimens, could be identified more often with the core biopsy than in biopsies obtained by transurethral resection. False negative diagnosis occurred when the tumor was not clearly visible on the computed tomography scan. No short-term side effects of clinical importance were found with the procedure.

Oral Contrast Media in CT of the Abdomen A Double-Blind Randomized Study Comparing an Aqueous Solution of Amidotrizoate, an Aqueous Solution of Iohexol and a Viscous Solution of Iohexol

In a double-blind randomized study 3 different preparations of oral contrast media for bowel opacification at CT of the abdomen have been compared. Plain aqueous solutions of amidotrizoate (9 mg I/ml) and iohexol (9 mg I/ml) were used as well as a preparation of iohexol (9 mg I/ml) to which a viscosity-increasing agent had been added. The distribution of the contrast media in the intestine, transit time and patient tolerance were evaluated. No significant differences were found regarding the distribution between the 3 preparations of contrast media, while there was a tendency for the transit time to be increased when the viscous preparation of iohexol was used. The aqueous solution of iohexol had the best taste, while the viscous preparation was markedly more difficult to drink. Aqueous solutions of iohexol and amidotrizoate were equal for bowel opacification and the addition of the viscosity-increasing agent did not improve the distribution of the contrast medium in the intestine.

Contrast enhancement in bladder tumors examined with CT urography using traditional scan phases.

Background Bladder assessment in an early contrast-enhancing computed tomography urography (CTU) phase requires that bladder tumors be enhanced using contrast material. Purpose To investigate the enhancement pattern in bladder tumors using a CTU protocol where the scan is enhancement triggered. Material and Methods Fifty patients diagnosed with bladder cancer were examined during the unenhanced (UP), corticomedullary (CMP), and excretory phases (EP). Twenty-one patients, all aged 50 years or older, were also examined during the nephrographic phase (NP). A ROI placed in the aorta was used to start the scan during the CMP when the attenuation reached 200 Hounsfield units (HU). The NP and EP were started with a 40 s and 300 s delay, respectively, after the CMP was finished. Attenuation and size measurements were made in the axial plane. Results Mean contrast enhancement of bladder tumors was 37, 25, and 17 HU in the CMP, NP, and EP, respectively. The differences in contrast enhancement were significant across all three phases. Eighty-eight percent of patients showed the highest contrast enhancement in the CMP. In 96% of the cases, contrast enhancement >20 HU was seen. The mean value of the shortest dimension of the bladder tumors was 22 ± 12 mm. Conclusion The contrast enhancement is significantly higher in the CMP than in the NP and EP, suggesting that the CMP is preferable when assessing the bladder in the early contrast enhancing phase.

Oral contrast media in CT of the abdomen. Iohexol of different concentrations as a gastrointestinal contrast medium.

In a double blind randomised study 3 different concentrations of iohexol for bowel opacification at CT of the abdomen were compared. Iohexol in a concentration of 4.5 mg I/ml, 6.75 mg I/ml and 9 mg I/ml was used. No significant differences between the 3 preparations of contrast media were found regarding the contrast effect, the distribution or patient tolerance. When using iohexol as a bowel contrast medium at CT the concentration of 4.5 mg I/ml is sufficient for bowel opacification.

Effect of superparamagnetic particles in agarose gels : a magnetic resonance imaging study

The effect of different preparations of superparamagnetic particles, designed as potential MR contrast media for the gastrointestinal tract (oral magnetic particles, OMP, diameter of 3.5 μm, iron content 20% by weight) and for the reticuloendothelial system (intravenous magnetic particles, IMP, mean diameter of 0.3 μm, iron content 30% by weight), were evaluated in agarose gels in vitro, using a 0.5 T whole body MR system. The iron content ranged from 2.1 × 10−4 to 2.1 × 10−1 mg Fe/ml in both preparations. Both preparations reduced the signal intensities substantially over a range of concentrations in spin echo sequences. Generally, the signal intensity decreased monotonously with concentration, except for IMP at low concentrations, at which a minor signal intensity increase was observed on T1 and proton density weighted images. The reduction of the signal intensity was stronger in gradient echo and phase contrast sequences, as compared to corresponding spin echo sequences with similar timing. Both IMP and OMP had a pronounced T2 effect, the effect of IMP being stronger than that of OMP. IMP had a relatively smaller T1 effect, whereas T1 was almost unaffected by OMP. Susceptibility artifacts occurred at higher concentrations of both OMP and IMP, in all sequences used. Thus, OMP reduced the signal intensity, without causing significant artifacts, on both T1 and T2 weighted images over a relatively wide range of concentrations.

Predictive factors for complete renal tumor ablation using RFA

Background Radiofrequency ablation (RFA) can be used to treat renal masses in patients where surgery is preferably avoided. As tumor size and location can affect ablation results, procedural planning needs to identify these factors to limit treatment to a single session and increase ablation success. Purpose To identify factors that may affect the primary efficacy of complete renal tumor ablation with radiofrequency after a single session. Material and Methods Percutaneous RFA (using an impedance based system) was performed using computed tomography (CT) guidance. Fifty-two renal tumors (in 44 patients) were retrospectively studied (median follow-up, 7 months). Data collection included patient demographics, tumor data (modified Renal Nephrometry Score, histopathological diagnosis), RFA treatment data (electrode placement), and follow-up results (tumor relapse). Data were analyzed through generalized estimating equations. Results Primary efficacy rate was 83%. Predictors for complete ablation were optimal electrode placement (P = 0.002, OR = 16.67) and increasing distance to the collecting system (P = 0.02, OR = 1.18). Tumor size was not a predictor for complete ablation (median size, 24 mm; P = 0.069, OR = 0.47), but all tumors ≤2 cm were completely ablated. All papillary tumors and oncocytomas were completely ablated in a single session; the most common incompletely ablated tumor type was clear cell carcinoma (6 of 9). Conclusion Optimal electrode placement and a long distance from the collecting system are associated with an increased primary efficacy of renal tumor RFA. These variables need to be considered to increase primary ablation success. Further studies are needed to evaluate the effect of RFA on histopathologically different renal tumors.

Periprocedural outcome after laparoscopic partial nephrectomy versus radiofrequency ablation for T1 renal tumors: a modified R.E.N.A.L nephrometry score adjusted comparison:

Background Comparable oncological outcomes have been seen after surgical nephrectomy and thermal ablation of renal tumors recently. However, periprocedural outcome needs to be assessed for aiding treatment decision. Purpose To compare efficacy rates and periprocedural outcome (technical success, session time, hospitalization time, and complications) after renal tumor treatment with laparoscopic partial nephrectomy (LPN) or radiofrequency ablation (RFA). Material and Methods The initial experience with 49 (treated with LPN) and 84 (treated with RFA) consecutive patients for a single renal tumor (diameter ≤ 5 cm, limited to the kidney) during 2007–2014 was evaluated. Patient and tumor characteristics, efficacy rates, and periprocedural outcome were collected retrospectively. The stratified Mantel Haenzel and Van Elteren tests, adjusted for tumor complexity (with the modified R.E.N.A.L nephrometry score [m-RNS]), were used to assess differences in treatment outcomes. Results Primary efficacy rate was 98% for LPN and 85.7% for RFA; secondary efficacy rate was 93.9% for LPN and 95.2% for RFA; and technical success rate was 87.8% for LPN and 100% for RFA. Median session (m-RNS adjusted P < 0.001; LPN 215 min, RFA 137 min) and median hospitalization time were longer after LPN (m-RNS adjusted P < 0.001; LPN 5 days, RFA 2 days). Side effects were uncommon (LPN 2%, RFA 4.8%). Complications were more frequent after LPN (m-RNS adjusted P < 0.001; LPN 42.9%, RFA 10.7%). Conclusion Both methods achieved equivalent secondary efficacy rates. RFA included several treatment sessions, but session and hospitalization times were shorter, and complications were less frequent than for LPN. The differences remained after adjustment for renal tumor complexity.

Long-term survival in unfavourable-risk mRCC patients after intratumoral administration of a cell-based allogeneic vaccine

Meeting abstracts Initial data from a Phase I/II study in patients with recently diagnosed metastatic RCC ([NCT01525017][1]) demonstrated that intratumoral administration of a cell based allogeneic vaccine adjuvant before nephrectomy was associated with a prominent intratumoral infiltration of CD8