Lars Bååth

European quadricentric evaluation of a breast MR biopsy and localization device: technical improvements based on phase-I evaluation

Abstract. Our purpose was to report about technical success, problems and solutions, as experienced in a first multicentre study on MR-guided localisation or vacuum biopsy of breast lesions. The study was carried out at four European sites using a dedicated prototype breast biopsy device. Experiences with 49 scheduled localisation procedures and 188 vacuum biopsies are reported. Apart from 35 dropped indications, one localisation procedure and 9 vacuum biopsies were not possible (3 times space problems due to obesity, 2 times too strong compression, 3 times impaired access from medially, 2 times impaired access due to a metal bar). Problems due to too strong compression were recognised by repeat MR without compression. During the procedure problems leading to an uncertain result occurred in eight vacuum biopsies, two related to the procedure: one limited access, and one strong post-biopsy enhancement. Improvements after phase-I study concerned removal of the metal bar, development of an improved medial access, of a profile imitating the biopsy gun, optimisation of compression plates and improved software support. The partners agreed that the improvements answered all important technical problems.

Internal fixation of 410 cervical hip fractures: A randomized comparison of a single nail versus two hook-pins

Totally, 410 patients with a cervical hip fracture were randomized between two methods of osteosynthesis: a single nail (Rydell) and two hook-pins (LIH). Seventy-five percent of the patients were women. Sixty-nine percent were alive after 2 years. The patients were followed up with clinical and radiographic examinations for 2 years postoperatively. No difference between the two groups were found regarding quality of reduction, early displacement within 3 months, extraction after healing, nonunion, late segmental collapse, or reoperation with a total hip arthroplasty. Nor did we find any differences between the two groups when selecting those alive after 2 years or when dividing the fractures in displaced and nondisplaced fractures.

Vasoconstriction of Isolated Arteries Induced by Angiographic Contrast Media A Comparison of Ionic and Non-Ionic Contrast Media Iso-Osmolar with Plasma

Angiographic contrast media (CM) may cause both vasodilatation and vasoconstriction, effects that can only be partly be explained by the medias hyperosmolality. The present study describes a CM-induced vasoconstriction of isolated rabbit coronary arteries that depends on chemotoxicity and ion content of the CM. Rings of arteries were mounted in tissue baths and the constrictions induced by different CM were measured. Iotrolan and iodixanol (nonionic dimers) caused the most powerful constrictions followed by iohexol (non-ionic monomer) and mannitol. Ioxaglate (ionic dimer) and diatrizoate (ionic monomer) caused no or weak constrictions. By comparing these findings with previous studies, it is concluded that non-ionic media cause vasoconstriction due to depolarization of the smooth muscle cells, an effect that for iohexol can be counteracted by addition of 30 mM NaCl. The ionic media seem to cause hyperpolarization of the cells. This difference between non-ionic and ionic CM might be one of the reasons for the lower tendency of non-ionic CM to cause vasodilatation clinically.

Reducing the Risk of Ventricular Fibrillation by Adding Sodium to Ionic and Non-Ionic Contrast Media with Low Iodine Concentration Coronary Perfusion of the Isolated Rabbit Heart with Meglumine Diatrizoate or Iopentol at 140 mg I/ml and 0–154 mmol Na+/l

To compare the fibrillatory propensity of low concentrations of contrast media (140 mg I/ml) the ionic, ratio 1.5, contrast medium meglumine diatrizoate, the non-ionic, ratio 3, medium iopentol and equimolar glucose (0.37 mol/l) were perfused into 35 isolated rabbit hearts. The three substances were compared at three levels of sodium concentration (0, 77 and 154 mmol Na+/l). Meglumine diatrizoate without sodium caused the highest frequency of ventricular fibrillation (91 %). Iopentol without sodium caused a significantly lower frequency of ventricular fibrillation (17%). Glucose without sodium caused no fibrillation. The addition of 77 or 154 mmol Na+/l significantly decreased the frequency of ventricular fibrillation of both meglumine diatrizoate (3 % and 6%) and iopentol (0%). Meglumine diatrizoate with sodium added caused a lower frequency of ventricular fibrillation than iopentol without sodium. At equal sodium concentrations (0, 77 and 154 mmol Na+/l) glucose caused smaller reduction in contractile force and heart rate than iopentol, and iopentol caused smaller reduction in contractile force and heart rate than diatrizoate. It is concluded that addition of sodium to ionic or non-ionic contrast media without sodium decreases the risk of ventricular fibrillation.

Sodium-calcium balance in nonionic contrast media. Effects on the risk of ventricular fibrillation in the isolated rabbit heart

RATIONALE AND OBJECTIVESDuring coronary arteriography the blood is replaced for a short period of time with a contrast medium (CM) solution. The CM may cause a risk of arrhythmias and ventricular fibrillation (VF). Previous investigations have shown that the addition of small amounts of sodium (10–30 mmol/L) to nonionic CM may decrease the risk of VF from these media. Calcium addition to nonionic CM may reduce a negative inotropic effect. In the current investigation, the changed risk of VF from nonionic CM with 19 to 30 mmol/L NaCl was studied when the media also contained calcium or calcium and magnesium. METHODSAn isolated rabbit heart model was used. The risk of arrhythmias and VF from the nonionic monomer iohexol and the nonionic dimer iodixanol containing 19 to 30 mmol/L NaCl with 0 to 2.5 mmol/L calcium as CaCl2 was studied. In the series with iodixanol, 0 to 0.95 mmol/L MgCl2 also was added to the solutions with sodium and calcium, but the role of magnesium was not especially evaluated in the investigation. RESULTSNonionic CM with small amounts of NaCl (19–30 mmol/L), without calcium or with calcium at the level of 0.05 to 0.3 mmol/L, caused the lowest risk of VF. When relatively higher additions of calcium reached the physiologic concentration of 2.5 mmol/L, the CM caused a greater risk of arrhythmias and VF. CONCLUSIONSWhen calcium is added to a nonionic CM, the concentration of calcium must be balanced against the NaCl concentration to minimize the risk of VF. Excessive calcium concentration will increase the risk of VF.

CNS-Effects from Subarachnoid Injections of Iohexol and the Non-Ionic Dimers Iodixanol and Iotrolan in the Rabbit

The neural tolerance of the new non-ionic dimer iodixanol was compared with that of the clinically used monomer iohexol and the dimer iotrolan. Behaviour of non-anaesthetised rabbits was monitored for 3 hours after intracisternal injection, at a dose-volume of 1 ml/kg of iodixanol 150 mg I/ml, iodixanol 320 mg I/ml, iohexol 350 mg I/ml, or iotrolan 300 mg I/ml (10 rabbits in each group). Iotrolan induced generalised seizures in 5 rabbits, iodixanol 320 mg I/ml in 2 rabbits, and iodixanol 150 mg I/ml in one rabbit. No excitative changes were observed in rabbits injected with iohexol, but compared with the dimeric contrast media the difference was not significant. Iohexol produced significantly more severe depressive changes than iodixanol 150 mg I/ml (p<0.01), iodixanol 320 mg I/ml (p<0.05), and iotrolan 300 mg I/ml (p<0.05). The results indicate that the excitative neurotoxic potential of the dimer iodixanol is likely to be lower than that of the clinically used dimer iotrolan, but slightly higher than that of iohexol. It may be expected that both dimers will produce a lower frequency of minor neurological adverse reactions than iohexol.

Contrast Medium-Induced Vasoconstrictions: An investigation of the vasoconstrictive action of iohexol in isolated rabbit coronary arteries

Angiographic contrast media (CM) may cause both vasodilatation and vasoconstriction. This study evaluates a contrast medium-induced vasoconstriction that occurs when isolated arteries are exposed directly to a CM. Segments of rabbit coronary arteries were mounted in tissue baths containing buffer solution. During the experiments the buffer solution was exchanged with iohexol iso-osmolar with plasma, which caused a temporary vasoconstriction of the vessel segments. The constriction did not depend on the degree of oxygenation of iohexol. The endothelium was not involved in the vasoconstriction. Prazosin slightly decreased the vasoconstriction and a small part of the constriction might thus depend on liberation of norepinephrine by iohexol. The constriction was totally inhibited by the calcium antagonist nifedipine, while it was augmented by addition of low concentrations of KCl to ihoexol. It is concluded that the otherwise safe CM iohexol causes vasoconstriction in vitro by depolarizing the smooth muscle cells and the nerve terminals in the vessel wall.

Effect of Sodium Addition to Non-Ionic Contrast Media on Cardiac Contractile Force Perfusion of the Isolated Rabbit Heart with Iohexol and Iopentol Containing 0 to 154 Mmol Na+/l added as NaCl

Cardiac contractile force after adding NaCl to the non-ionic contrast media iohexol and iopentol was investigated in the isolated rabbit heart. Iodine concentrations of 150, 300 and 350 mg I/ml were used with sodium concentrations ranging from 0 to 154 mmol/l. From physiologic experiences of nutrient solutions it should follow that a sodium-free solution of a non-ionic contrast medium, which also has the lowest hypertonicity, should cause the smallest decrease in contractile force. However, a small amount of sodium added to the contrast medium solutions, in the range of 19.25 to 38.5 mmol/l, caused the least decrease in contractile force. The decrease in contractile force was significantly more pronounced when no sodium was added or when larger amounts of sodium were added. A small amount of sodium also decreases the risk of ventricular fibrillation. Thus there is a possibility that addition of sodium could reduce the adverse effects of cardioangiography.

Image quality and safety after iodixanol in intravenous urography; a comparison with iohexol.

A double-blind, randomized phase III study compared intravenous urography in 100 adult patients receiving iodixanol 320 mgI ml-1 (Visipaque) with 99 patients receiving iohexol 350 mgI ml-1 (Omnipaque). The aim of the study was to investigate differences in image quality between a non-ionic dimeric contrast medium (CM) and a non-ionic monomer at 40 ml per patient and 60-100 ml per patient volume levels. There were no statistically significant differences between iodixanol and iohexol with respect to overall diagnostic information, which was found to be optimal in 86% and 79%, respectively. Immediately after the injection, the renal border was better delineated with iohexol than with iodixanol (p = 0.0001). Marked papillary blush occurred more often in the iodixanol group (16%) than in the iohexol group (0%), as did visualization of the collecting ducts (24% vs 5%) (p = 0.001). The incidence of adverse events was similar and low for both contrast media. In patients who received the higher doses of CM (60-100 ml), the frequency of discomfort was significantly lower after iodixanol than after iohexol (p = 0.006). We conclude that, in intravenous urography, iodixanol provides at least as good image quality as does iohexol. Iodixanol may cause less discomfort than iohexol, in particular when larger volumes of CM are injected.

Adding Sodium and Calcium Ions to the Contrast Medium Iodixanol Reduced the Risk of Ventricular Fibrillation During Perfusion of the Left Coronary Artery in Pigs: Effects of Electrolytes, Viscosity, and Chemotoxicity of an Isotonic Perfusate 1

RATIONAL AND OBJECTIVES The effects of electrolytes, viscosity, and chemotoxicity of a plasma-isotonic iodine contrast medium iodixanol were compared with regard to its propensity to cause ventricular fibrillation (VF). MATERIALS AND METHODS The left coronary artery of pigs was perfused with five isotonic solutions: iodixanol 320 mg I/mL with 19 mmol/L NaCl + 0.3 mmol/L CaCl2, Iod 320+Mann (iodixanol 320 mg I/mL + 50 mmol/L mannitol), Mann+Na/Ca (240 mmol/L mannitol with 19 mmol/L NaCl + 0.3 mmol/L CaCl2), Mann (275 mmol/L mannitol) and Ringer. The first two solutions have at 37 degrees C a viscosity of approximately 13 mPa x s while the others have a viscosity < 1 mPa x s. In eight pigs, each test solution was injected twice into the left coronary artery in random order for 10 seconds (injection volume, 20 mL). In 15 pigs, each of the solutions was injected in random order for 11-40 seconds through the end-hole of a wedged 5F balloon catheter in left coronary artery. Injection rate was 0.5 mL/sec until VF occurred. If VF occurred, injection was stopped and the heart was defibrillated. If VF did not occur, the perfusion period was 40 seconds. RESULTS The 10-second perfusions caused no VF. The 40-second perfusions with iodixanol 320 mg I/mL with 19 mmol/L NaCl + 0.3 mmol/L CaCl2 or Ringer caused no VF (0%). Iod 320+Mann caused nine VF (60%) after 35 +/- 4 seconds (SEM). Mann+Na/Ca caused 14 VF (93%) after 30 +/- 2 seconds. Mann caused 15 VF (100%) after 24 +/- 2 seconds. Iodixanol 320 mg I/mL with 19 mmol/L NaCl + 0.3 mmol/L CaCl2 and Ringer caused fewer VF than all other solutions (P < .05-.001). Iod 320+Mann caused fewer VF than Mann (P < .05). Iod 320+Mann caused VF later than Mann+Na/Ca or Mann (P < .02 and P < .01). Mann+Na/Ca caused VF later than Mann (P < .05). CONCLUSION The results fit with a concept that VF starts when the electrolyte composition of the interstitial fluid in the myocardium is sufficiently nonphysiologic. The more physiologic the electrolyte composition of the perfusion fluid, and the higher its viscosity, the slower the composition of the interstitial fluid will be changed, and VF will occur later (or not at all).