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Biomedical subjects

J A Jakobsen

Publications and source records attributed to J A Jakobsen.

At least 19 recordsLinked to original sources
PubMed2005

Uterine fibroid embolization can still be improved: observations on post-procedure magnetic resonance imaging.

PURPOSE: To evaluate the efficacy and completeness of uterine fibroid embolization (UFE) measured by changes in volume and signal intensity at magnetic resonance imaging (MRI), and to compare with clinical outcome. MATERIAL AND METHODS: 40 women with symptomatic uterine fibroids underwent bilateral uterine artery embolization. At MRI studies, including post-contrast sequences before and repeatedly after treatment, the uterus and dominant fibroids were evaluated for volume, location, and contrast enhancement. Prior to treatment, all myomas showed significant contrast enhancement. The mean uterine volume was 929 ml. Clinical examinations with emphasis on menorrhagia, pelvic pain, and urinary dysfunction were performed before and 6 and 12 months after treatment. RESULTS: UFE was bilaterally successful in 38 patients. After UFE, MRI showed no enhancement of myomas in 30 patients. In 8 patients, post-procedural MRI revealed partially remaining vascularization of fibroids despite angiographically complete embolization of the uterine arteries. On average, uterine volume decreased by 46.2% at 12 months. There was significant improvement of symptoms in the majority of patients, but slightly less improvement in patients with partially remaining vascularization of myomas. CONCLUSION: UFE causes significant volume reduction of myomas and clinical improvement. MRI can reveal remaining vascularization in myomas despite angiographically complete embolization of uterine arteries.

Adult↗
PubMed2004

Complications following ultrasound-guided thoracocentesis.

PURPOSE: To retrospectively register the number and type of complications following ultrasound-guided thoracocentesis, and to evaluate the need for routine chest X-ray after the procedure. MATERIAL AND METHODS: Complications were retrospectively registered from the radiological and clinical reports of 371 consecutive patients who had undergone thoracocentesis with a total of 711 procedures. RESULTS: The mean volume evacuated was 823ml (range 0-3600ml). Twenty (2.8%) pneumothoraces were found after 711 thoracocenteses, but in no case was chest tube drainage necessary. Hemoptysis occurred in one patient. CONCLUSION: Ultrasound-guided thoracocentesis was found to be a safe procedure. Based on these results, no reason was found to introduce an upper limit of the amount of fluid drained in one session. Routine follow-up chest X-ray is not justified in the absence of clinical symptoms.

Adolescent↗
PubMed2003

Doppler examination of the allografted kidney.

A comprehensive ultrasound examination of the transplanted kidney includes a Doppler examination. Duplex Doppler, color Doppler and power Doppler can all reveal important information. In addition, calculation of the resistance and pulsatility indices to quantify changes in the spectral Doppler waveform can be of great help, particularly in the first weeks and months following a transplantation. The Doppler part of the examination should evaluate the vessels to and from the transplant, as well as the parenchyma with calculations of indices to detect the presence of increased vascular resistance. The conclusions drawn from the Doppler-derived information combined with the results from gray-scale scanning and clinical information will very often be of clinical significance for the handling of the patient.

Humans↗
PubMed2002

Contrast medium extravasation injury: guidelines for prevention and management.

Extravasation of contrast material is a well-recognized complication of contrast-enhanced imaging studies. The management of this complication is contentious; therefore, the Contrast Media Safety Committee of The European Society of Urogenital Radiology decided to review the literature and issue guidelines. A comprehensive literature search was carried out. The resulting report was discussed at the 8th European Symposium on Urogenital Radiology in Genoa, Italy. Automated power injection may result in extravasation of large volumes and may or can lead to severe tissue damage. Infants, young children and unconscious and debilitated patients are particularly at risk of extravasation during contrast media injection. Fortunately, most extravasations result in minimal swelling or erythema, with no long-term sequelae; however, severe skin necrosis and ulceration may occur. Large volumes of high osmolar contrast media are known to induce significant tissue damage. Compartment syndrome may be seen associated with extravasation of large volumes. Conservative management is often adequate, but in serious cases the advice of a plastic surgeon is recommended. Based on the review simple guidelines for prophylaxis and management of contrast medium extravasation injuries are proposed.

Adult↗
PubMed2001

Ultrasound contrast agents and their use in urogenital radiology: status and prospects.

Ultrasound contrast agents (USCAs) for intravenous use are usually microbubbles with a mean diameter less than that of a red blood corpuscle and filled with gas. The USCAs may improve information about tissue characteristics and physiology by enhancing B-mode imaging, all Doppler modalities and by means of contrast-specific imaging, e.g. harmonic and stimulated acoustic imaging. Results from preclinical experiments have been promising, and several of these have been reproduced in clinical studies. This includes improved evaluation of renal vasculature and parenchyma, assessment of vesicoureteral reflux in children, assessment of tubal patency in women, and evaluation of prostate diseases and erectile dysfunction in men. Some of the physical limits of the ultrasound technology, as well as the operator-dependent factors, can probably never be overcome by the use of USCAs; however, the development of USCAs is now about to provide uroradiologists with potentially efficacious products for the benefit of the patient.

Animals↗
PubMed2001

Ultrasound contrast agents: clinical applications.

Ultrasound contrast agents (USCA) for intravenous injections are usually gas-filled microbubbles with a mean diameter less than that of a red blood corpuscle. There are only a few products on the market at the time of this writing, but several companies have various agents under development. This paper covers both established USCA on the market, and some new agents under clinical evaluation. The potential of improving ultrasound imaging using USCA depends on several factors. These factors include the pharmacokinetic and pharmacodynamic properties of the products, which determine the effects they have on various ultrasound imaging techniques. Furthermore, the proper clinical application of the agents requires a combination of technical and medical knowledge by the examiner, dedicated equipment, a disease that can be diagnosed or characterised by ultrasound and USCA, and a cooperative patient. Taking into account these factors, USCA can be used for improving the detection, characterisation and follow-up of diseases of several vascular beds and parenchymal organs from head to foot.

Blood Vessels↗
PubMed2001

Contrast-enhanced ultrasound Doppler examination of the retrobulbar arteries.

PURPOSE: To evaluate the diagnostic usefulness of an ultrasound contrast agent in examination of the retrobulbar arteries. MATERIAL AND METHODS: Ten healthy volunteers received a galactose-based echo-contrast medium (Levovist) by i.v. infusion. The ophthalmic, central retinal, the nasal and the temporal posterior ciliary arteries and the short ciliary arteries were studied in 19 eyes by color and spectral Doppler ultrasonography before and after contrast administration. Peak systolic and end diastolic velocities and spectral Doppler indices (pulsatility and resistive) were assessed. The quality of the spectral and color Doppler imaging of the arteries were visually graded on a 5-point scale. RESULTS: There were significant differences in pre- and post-contrast peak systolic velocities in the ophthalmic arteries (p<0.05), but not in the other retrobulbar arteries, or in any of the spectral Doppler indices. After contrast administration the mean spectral Doppler score for vessels poorly visualized before contrast increased from 2.2 (+/-0.4) to 3.1 (+/-0.9). The number of short ciliary arteries with sufficient spectral Doppler quality increased from 7 prior to contrast to 14 following contrast. Prior to the infusion of Levovist, 62 (73%) out of 85 retrobulbar arteries could be evaluated with a sufficient spectral Doppler quality. Following the administration of contrast 66 (78%) arteries had sufficient spectral Doppler quality. However, by combining the results of the pre- and post-contrast examinations, sufficient spectral Doppler quality was obtained in 77 (91%) of the 85 retrobulbar arteries. CONCLUSION: Contrast enhancement increased the number of detectable retrobulbar vessels. However, in the case of good quality pre-contrast imaging of the retrobulbar vessels, the use of Levovist did not add any substantial diagnostic information. The optimal spectral Doppler results were obtained when both pre- and post-contrast examinations were performed.

Adult↗
PubMed1997

Iopentol (Imagopaque 350) compared with diatrizoate (Urografin 370) in cerebral CT. A clinical trial assessing immediate and late (7 days) adverse events and diagnostic information (visualization quality and Hounsfield unit measurements).

The non-ionic contrast medium iopentol (Imagopaque, Nycomed Imaging AS, Oslo, Norway) 350 mg I/ml was compared for safety and efficacy with the ionic contrast medium diatrizoate (Urografin, Schering AG, Berlin, Germany) 370 mg I/ml in a randomized, double-blind, parallel-group clinical trial in cerebral computed tomography (CT). The numbers of participating patients was 79; forty in the iopentol group and 39 in the diatrizoate group. Safety was evaluated by assessing the numbers of patients reporting immediate adverse events (up to 30 min after injection) and delayed adverse events (within 7 days after the examination). Efficacy was expressed as the quality of visualization of the cerebral lesions after injection of the contrast medium. In addition, Hounsfield units were measured pre- and post-contrast. No patient in either group experienced any serious adverse event. The frequency of patients with immediate adverse events was statistically significantly lower in the iopentol group (23%) than in the diatrizoate group (64%), p = 0.0003. Delayed adverse events were also significantly less frequent in the iopentol group (43%) than in the diatrizoate group (69%), p = 0.047. Patients in the iopentol group reported significantly less discomfort (53%), especially sensation of warmth, than patients in the diatrizoate group (92%), p = 0.0001. The intensity of adverse events and injection-associated discomfort seemed, in general, to be lower for patients in the iopentol group. No difference was found between the two contrast media regarding efficacy.

Brain↗
PubMed1997

Delayed CT of the kidneys after iopentol (Imagopaque 350) injection in patients with normal renal function. An assessment of the gradual decrease in opacification over 32 h after injection.

The elimination of the non-ionic contrast medium iopentol (Imagopaque, Nycomed Imaging AS, Oslo, Norway) from the kidneys was investigated in adult patients with normal renal function referred for cerebral computed tomography (CT). Twenty-four patients were included in the study. Each patient was given one intravenous injection of 50 ml iopentol 350 mg I/ml. CT scans of the kidneys were taken before, immediately after, 8 h after and 32 h after the injection of contrast medium. To assess the rate of iopentol disappearance, calculations were made for the cortex, medulla and aorta, based on changes from the baseline (pre-contrast) measurements, in Hounsfield units (HU). The median estimated time for disappearance was 28 h from the cortex, 32 h from the medulla and 8 h from the aorta. Thus, a small retention of contrast medium can usually be seen after normalization of aortic HU values.

Brain↗
PubMed1997

Effect of ultrasound contrast medium in color Doppler and power Doppler visualization of blood flow in canine kidneys.

PURPOSE: To examine the effect of an ultrasound contrast medium (UCM) in the visualization of parenchymal blood flow by means of color Doppler and power Doppler sonography. MATERIAL AND METHODS: Nonenhanced and UCM-enhanced Doppler images of canine kidneys were obtained in a transversal plane during various states of flow reduction in the anterior branch of the renal artery. The UCM consisted of air-filled shell-stabilized microballoons (half-life approximately 2 min). The images were evaluated blindly by 4 observers who rated the amount of flow signal in the cortex and medulla, and categorized the flow state (normal, reduced or no flow) in the anterior part of the kidney. RESULTS: The UCM increased the area of Doppler signals in the cortex and outer medulla during normal or reduced blood flow. The border between nonperfused and normally perfused parenchyma was more distinct with the UCM. The categorization of the regional flow state was more correct with the UCM. Improvement with the UCM was greatest when the nonenhanced Doppler images had suboptimal intensity, but positive effects with the UCM were also seen in recordings with adequate precontrast intensity. Color blooming artifacts sometimes occurred on the side of the kidney facing away from the transducer. CONCLUSION: The UCM improved the color Doppler and power Doppler visualization of the parenchymal blood flow in the canine kidney, and allowed a more correct categorization to be made of the regional blood flow state.

Air↗
PubMed1996

Determination of glomerular filtration rate with Visipaque in patients with severely reduced renal function.

Iodixanol (Visipaque, Nycomed Imaging AS, Oslo, Norway), and isotonic, dimeric and non-ionic contrast medium (CM), and iohexol (Omnipaque, Nycomed Imaging AS, Oslo, Norway), a low-osmolar, monomeric and non-ionic contrast medium, were used as glomerular filtration rate (GFR) markers in patients with severely impaired renal function. Different methods for determining GFR were compared. A total of 16 patients with s-creatinine > 400 mumol/l were enrolled in the study; 8 in each CM group. Serum-iodine was measured, and plasma CM clearance was determined using the Bröchner-Mortensen method, the single-sample method and conventional method. The ratios between the results obtained from the conventional method and each of the two other methods were calculated. These data were plotted against the mean of the pairs compared, and the upper and lower limits of agreement were calculated as the mean ratio +/- 2SD. The comparison showed a high degree of agreement between methods, and the two simpler methods seem to be good alternatives to the conventional method, which gave good estimates of GFR (vs that determined by means of renal 125I-iothalamate clearance) when 24-h blood samples were included. However, slight overestimations of GFR, due to extrarenal excretion of the CM, were observed. In summary, serum clearance of iodixanol, as determined by the Bröchner-Mortensen method or single-sample method seems to be a simple and accurate marker for GFR in patients with severely reduced renal function. The findings obtained with iodixanol were similar to those obtained with iohexol.

Adult↗
PubMed1996

Renal experience with Visipaque.

The renal effects of the new dimeric non-ionic contrast medium Visipaque were investigated in healthy volunteers and in patients with severe renal failure. Visipaque caused no changes in GFR after i.v. injections to healthy volunteers and less changes in tubular function than monomeric CM. Small and transient changes in GFR were observed in predialytic patients both with Visipaque and with the monomeric Omnipaque. A delayed excretion of both CM was observed in these patients and no differences were observed between the two CM as far as tubular enzymes excretion and glomerular functional parameters are concerned. More iodine was retained in the kidney after Visipaque than after monomers, but this was not correlated with changes in tubular parameters and in GFR. Thus, Visipaque was well tolerated in subjects with normal renal function and in patients with severe renal failure.

Contrast Media↗
PubMed1996

Angiography with nonionic X-ray contrast media in severe chronic renal failure: renal function and contrast retention.

The effects of contrast media on renal function and the cortical retention of contrast media after abdominal angiography were investigated. Sixteen nondiabetic patients with predialytic chronic renal failure received either the nonionic dimeric contrast medium iodixanol or the monomeric contrast medium iohexol in a double-blind randomized study. All patients were well hydrated before, during and after angiography. Mean 99mTc-DTPA clearance was 14.0 ml/min/1.73 m2 in the iodixanol group, and 9.3 ml/min/1.73 m2 in the iohexol group at baseline. No statistically significant changes were seen after angiography. Serum creatinine increased significantly 48 and 72 h after angiography in both groups, and then normalized. Creatinine clearance was reduced only in the iohexol group, at 72-96 h. The urinary excretion of renal enzymes and of total protein did not change significantly. No patients developed oliguria or required dialysis during the 7-day observation period. Increased attenuation in the renal cortex, measured by computed tomography and probably reflecting intracellular retention of contrast medium, peaked at 24 h, and was observed in both groups during the follow-up period. Thus, although transient and minor changes in glomerular filtration rate were noted, both iodixanol and iohexol were safe for use in angiography in nondiabetic patients with severe chronic failure when the patients were well hydrated.

Adult↗
PubMed1995

Renal effects of iodixanol in healthy volunteers and patients with severe renal failure.

Contrast medium- (CM) induced nephropathy may be evident from symptoms ranging from acute renal failure to minor changes in tubular function tests. While the incidence is usually low, it increases with the presence of risk factors and when arterial injections are made. The pathogenesis is not fully understood. No specific therapy exists, but in most cases it can be prevented by ensuring that the patient is well hydrated prior to injection of CM. The extended phase 1 study with iodixanol (Visipaque) included detailed investigations on its renal effects. No changes in glomerular filtration rate (GFR) were found. Even though enzymuria was less pronounced after injection of iodixanol than after various monomeric CM, a somewhat higher degree on intrarenal retention of CM was observed on CT examination of the kidneys after iodixanol. In nondiabetic patients suffering from severe renal failure, angiography with either iodixanol or iohexol caused no changes in GFR, or in urinary excretion of protein and enzymes. However, a higher degree of contrast retention than that seen in healthy volunteers was found.

Acute Kidney Injury↗