MR-safety in clinical practice at 7T: Evaluation of a multistep screening process in 1819 subjects.

INTRODUCTION: MR facilities must implement and maintain adequate screening and safety procedures to ensure safety during MR examinations. The aim of this study was to evaluate a multi-step MR safety screening process used at a 7T facility regarding incidence of different types of safety risks detected during the safety procedure. METHODS: Subjects scheduled for an MR examination and having entered the 7T facility during 2016-2019 underwent a pre-defined multi-step MR safety screening process. Screening documentation of 1819 included subjects was reviewed, and risks identified during the different screening steps were compiled. These data were also related to documented decisions made by a 7T MR safety committee and reported MR safety incidents. RESULTS: Passive or active implants (n = 315) were identified in a screening form and/or an additional documented interview in 305 subjects. Additional information not previously self-reported by the subject, regarding implants necessitating safety decisions performed by the staff was revealed in the documented interview in 102 subjects (106 items). In total, the 7T MR safety committee documented a decision in 36 (2%) of the included subjects. All of these subjects were finally cleared for scanning. CONCLUSION: A multi-step screening process allows a thorough MR screening of subjects, avoiding safety incidents. Different steps in the process allow awareness to rise and items to be detected that were missed in earlier steps. IMPLICATIONS FOR PRACTICE: Safety questions posed at a single timepoint during an MR screening process might not reveal all safety risks. Repetition and rephrasing of screening questions leads to increased detection of safety risks. This could be effectively mitigated by a multi-step screening process. A multi-disciplinary safety committee is efficient at short notice responding to unexpected safety issues.

Aneurysm clip MR artifacts. Titanium versus stainless steel and influence of imaging parameters.

PURPOSE: The aim of this study was to evaluate the extent to which titanium aneurysm clips could improve the quality of MR imaging compared with stainless steel clips, and to determine whether the clip artifacts could be reduced by controlling certain MR imaging parameters in frequently used pulse sequences. MATERIAL AND METHODS: The metal artifacts induced by 3 aneurysm clips were compared in 3 pulse sequences. The clips were: a Yasargil titanium aneurysm clip FT 752 T; a Yasargil standard aneurysm clip FE 752 K; and, for comparison, a ferromagnetic Scoville aneurysm clip En-58J. The pulse sequences were: spin echo (SE); gradient echo (GE); and fast SE. An evaluation was made of 3 imaging parameters with regard to their influence on the size of the metal artifacts. The parameters were: bandwidth; echo time (TE); and echo-train length. RESULTS: The titanium clip showed artifacts that were about 60% smaller than those from the stainless steel clip. The only parameter that influenced artifact size to any major degree was bandwidth in the SE sequences but not in the GE sequences. GE sequences induced larger artifacts than SE sequences and showed larger artifacts with longer TE. CONCLUSION: Titanium aneurysm clips reduced MR artifacts by approximately 60% compared to stainless steel clips. Artifacts were further reduced by using SE-based sequences with a high bandwidth or, if necessary, GE sequences with a low TE.

Embolization of the liver in the management of metastatic carcinoid tumors.

Eight patients with metastatic carcinoid tumors and the carcinoid syndrome were treated with gelatin foam embolization of the hepatic arterial tree. The aims were to reduce the tumor mass in the liver and to eliminate the carcinoid syndrome. The effects of the treatment were judged from arteriograms, CT scans, and the levels of serotonin in blood and 5-HIAA in urine, as well as from the clinical symptoms. The mean follow-up time was 12.5 months. In all patients the liver tumor mass was reduced after embolization, and this reduction persisted for at least 6 months in seven patients. After treatment, reduced serotonin levels in blood were measured in four patients and reduced 5-HIAA levels in urine in seven patients. In five patients the carcinoid syndrome disappeared after embolization, but after 6 months two of these five patients had regained symptoms. Adverse reactions were minor consisting of a slight fever, reversibly increased serum levels of liver enzymes, and abdominal pain. In our experience, the hepatic embolization is a simple and safe method of giving relief from the carcinoid syndrome.

[Dilatation of esophageal strictures using a balloon catheter]. / Dilatation der Oesophagusstrikturen mit einem Ballonkatheter.

The technique of balloon catheter dilatation of benign esophageal strictures is presented. A general anesthetic is unnecessary which is an advantage in older patients. Moreover, the encouraging results and the absence of complications support the opinion that balloon catheter dilatation is an excellent alternative in the treatment of esophageal strictures.

Pharmacologic manipulation of lower esophageal sphincter pressure. A possible means of treatment of variceal bleeding.

Ten patients with portal hypertension and esophageal varices had percutaneous transheptic portography with selective catheterization of the short gastric or left gastric vein. The effect was studied on variceal blood flow after injection of various drugs (vasopressin IV, pentagastrin IV, somatostatin IV, domperidone IV, and methylcholine SC). Vasopressin had no effect on variceal flow; pentagastrin gave a total occlusion of flow in five of nine patients; somatostatin interrupted the flow in one of four patients; domperidone obstructed flow completely in one patient, while another receiving the same dose was unaffected; methylcholine did not affect the flow in three patients examined.

Preoperative diagnosis and evaluation of hepatic tumor resectability.

In the interpretation of patients with primary and secondary tumors of the liver, different radiologic procedures play an important role. We discuss ultrasound, computerized tomography, and angiography; the advantages and drawbacks of these modalities; and how they should be used when surgery or infusion chemotherapy is planned.

Radiological diagnosis in proven intraabdominal abscess formation: a comparison between plain films of the abdomen, ultrasonography and computerized tomography.

Plain films of the abdomen, ultrasonography, and computed tomography were performed on 180 patients to rule out an intraabdominal abscess. The efficacy of the different modalities was reviewed in retrospect. Thirty-six of these 180 patients had a definite abscess formation. This was demonstrated in 65% of the plain film examinations, in 44% by ultrasonography, and in 94% by computerized tomography. Computed tomography seems efficient in ruling out abdominal abscess.

Pharmacologic influence on esophageal varices: a preliminary report.

Selective catheterization of the left gastric vein was performed after percutaneous transhepatic portography (PTP) in patients with portal hypertension and esophageal varices. Following the hypothesis that drugs increasing the lower esophageal sphincter (LES) pressure may obstruct the variceal blood flow through the lower esophagus, the effect of different drugs (i.e., intravenous injection of vasopressin, pentagastrin, domperidone and somatostatin and subcutaneous injection of metacholine) on the variceal blood flow was examined. Vasopressin did not change the variceal blood flow; pentagastrin, with its known effect of increasing the LES pressure produced a total interruption of the flow in four of eight patients; domperidone, also known to increase the LES pressure obstructed the variceal blood flow in the only patient examined with this drug; somatostatin has no reported action on the LES but blocked the flow in one of two patients; and metacholine, reported to increase the LES pressure did not produce any change in the flow in the three patients examined. LES pressure was recorded before and during vasopressin infusion in seven patients with portal hypertension and esophageal varices. No reaction on the pressure was found. The patient number in the study is small and the results are nonuniform but still they suggest that drugs increasing the LES tonus might be useful to control variceal blood flow.

Evaluation of splenic embolization in patients with portal hypertension and hypersplenism.

Twenty-five patients with hypersplenism caused by portal hypertension were treated by repeated partial splenic embolization. Fourteen surviving patients were followed for up to six years showing a good response on peripheral blood count and bleeding tendency. Three patients died in connection with the treatment and another eight died within half a year because of the underlying liver disease. The discomfort and complications of fever, pain, pleural effusion, and abscess formation and the possibility to avoid these by repeated partial embolization under antibiotic cover are discussed. The results are compared with reports in the reviewed actual literature and the splenic embolization is given a place among the means of a successful selective symptomatic treatment of partial hypertension.

Angiographic and computed tomographic appearance of secondary carcinoid of the liver.

Liver angiograms of 27 patients with hepatic carcinoid metastases were analyzed for distribution, size, degree of vascularity, and patterns of tumor staining. Computed tomography (CT) scans were evaluated before and after bolus contrast administration in 13 of the cases. The diagnostic capability of the two procedures was compared. Angiography detected metastases, some less than 1 cm in size in all 13 patients; in 5 of 13 cases (38.5%) CT did not detect any hepatic metastases. In the eight patients in whom CT demonstrated metastases, the patterns of lesions and usefulness of contrast varied. Angiography is essential for evaluation of patients with suspected carcinoid metastases to the liver.

Patient radiation doses in upper GI examinations: a comparison between conventional and double-contrast techniques.

A total of 60 patients, divided into 3 groups with 20 patients in each, were examined with 3 different techniques: group 1 -- conventional technique, exposure at 120 kV; group 2 -- double-contrast technique (hypotonic gastrography, HG), exposure at 80 kW; group 3 -- HG, exposure at 120 kV. All examinations were performed in the same examination room and by the same radiologist. Absorbed doses to skin, thyroid, breasts, and gonads as well as energy imparted were measured. The only significant dose enhancements found when using double-contrast instead of conventional technique were in the female breasts and then only if the voltage was in the lower range. With exposure at 120 kV there was little difference in absorbed dose, but a significant advantage with respect to energy was imparted when using a double-contrast technique instead of a conventional technique. The testes doses were very low in all 3 types of examinations, and it seems that use of a testes shield is hardly motivated. With regard to both diagnostic accuracy and patient radiation dose, there can be no reason to use a conventional technique for upper GI examinations.

Comparison of the excretion of sodium and meglumine diatrizoate at urography with simulated compression: an experimental study in the rat.

In the experimental model in the rabbit the excretion of sodium and meglumine diatrizoate, respectively, have been compared. Urographic density which was estimated through renal pelvic volume as calculated according to previous experiments (Owman 1978; Owman & Olin 1980) and urinary iodine concentration, is suggested to be more accurate than mere determination of urine iodine concentration and diuresis when evaluating and comparing urographic contrast media experimentally. More reliable dose optima are probably found when calculating density rather than determining urine concentrations. Of the examined media in this investigation, the sodium salt of diatrizoate was not superior to the meglumine salt in dose ranges up to 320 mg I/kg body weight, while at higher doses sodium diatrizoate gave higher urinary iodine concentrations and higher estimated density.

Regional, portal hypertension in chronic pancreatitis.

Because of a close anatomical relationship to the splenic vein chronic pancreatitis can cause obstruction to the splenic outflow. Regional portal hypertension develops and collateral flow sometimes gives rise to gastric and oesophageal varices which can cause life-threatening bleeding. Three cases with regional portal hypertension secondary to chronic pancreatitis are presented. Two of them were treated with surgical splenectomy and the third had an embolization of the splenic artery. Regional portal hypertension should be suspected in a patient with a history of chronic pancreatitis who is bleeding from gastric of oesophageal varices. The treatment of choice is surgical splenectomy. In high risk patients embolization of the splenic artery can be tried.

[Experience with the percutaneous transhepatic insertion of a bile duct endoprosthesis (author's transl)]. / Erfahrungen mit einer percutan-transhepatisch eingesetzten Gallengangs-Endoprothese.

In thirty patients with extrahepatic cholestasis because of a malignant tumor a permanent bile endoprosthesis was inserted nonsurgically. As prosthesis a teflon tube (OD/ID4.0/3.0mm) was used without side holes (13 cases) or with side holes (17 cases). The bile was drained through the endoprosthesis during a period of 1-32 weeks. The drainage function of the endoprosthesis without side holes was classified as partially effective in seven cases and as insufficient in six cases. The drainage function of the endoprosthesis with side holes was judged as optimal in four cases, partially effective in ten and insufficient in three cases. The dysfunction of the endoprosthesis in nine of thirty cases was caused by lack of side holes, spontaneous occlusion or spontaneous dislocation of the prosthesis. Eight patients developed symptoms of cholangitis. In four cases sepsis occurred after insertion of the prosthesis. One patient died from the sequelae of an intrahepatic pseudoaneurysm, which had developed from a damaged segmental artery following the transhepatic bile drainage.