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Biomedical subjects

S Dymarkowski

Publications and source records attributed to S Dymarkowski.

At least 19 recordsLinked to original sources
PubMed2006

Ovarian torsion in a premenarcheal girl: MRI findings.

Adnexal torsion is an uncommon cause of severe lower abdominal pain in women and is often difficult to distinguish from other acute abdominal conditions. However, adnexal torsion should be considered in premenarcheal girls admitted with acute abdominal pain and evidence of an ovarian mass. Accurate and early radiological diagnosis is mandatory immediately after onset of clinical symptoms in order to preserve the viability of the ovary. Ultrasound (US) is usually the first line examination performed in an emergency setting, but computed tomography (CT) and magnetic resonance imaging (MRI) can be useful in case of ambiguous US findings, especially in patients with sub-acute symptoms and a suspected adnexal mass. This case report describes the additional value of MRI in a premenarcheal girl with sub-acute right fossa pain.

Abdomen, Acute↗
PubMed2006

First trimester diagnosis of sirenomelia.

We present a case of sirenomelia diagnosed on a first trimester ultrasound at 10 weeks' gestation and confirmed on 3D-ultrasound and MRI. The pregnancy was terminated at 15 gestational weeks and the post-mortem examination, including RX and microscopy, is presented. The sirenomelia sequence is a rare and lethal anomaly characterized by fusion, rotation, hypotrophy or atrophy of the lower limbs and severe urogenital abnormalities leading to oligohydramnios in the second half of pregnancy. Our case illustrates that the diagnosis of sirenomelia can be reliably made in the first trimester.

Abortion, Eugenic↗
PubMed2004

Quantifying myocardial deformation throughout the cardiac cycle: a comparison of ultrasound strain rate, grey-scale M-mode and magnetic resonance imaging.

Strain rate imaging (SRI) is a new ultrasound (US) approach to the quantification of regional myocardial deformation. It previously has been validated in vitro and in vivo against other imaging techniques. However, in all such studies, only peak strain values were compared, and the temporal evolution of the strain curve was not studied. Yet, it is the temporal evolution of the strain curves that contains the more important clinical information (e.g., asynchrony, viability, etc). Thus, the aim of this study was to compare the evolution of strain during the complete cardiac cycle as measured by US SRI, US grey-scale M-mode and magnetic resonance imaging (MRI). In 10 healthy volunteers and 20 patients with chronic ischaemic heart disease, radial deformation of the inferolateral segment of the left ventricle was measured by US SRI, US M-mode and MRI. The correspondence of the temporal characteristics of these strain curves were compared by defining an intraclass correlation coefficient (ICC). In healthy volunteers, an overall good agreement (mean ICC: 0.75 and 0.63 for systole and diastole) was found between the different methods. However, in patients with abnormal segmental deformation and low peak strain values, the agreement was less (mean ICC: 0.42 and 0.32), but remained within acceptable limits for clinical decision making. Myocardial deformation measurements using SRI correlated well with MRI and US M-mode measurements throughout the complete cardiac cycle.

Coronary Stenosis↗
PubMed2003

The value of fast MR imaging as an adjunct to ultrasound in prenatal diagnosis.

The aim of this study was to evaluate the role of MR imaging of the fetus to improve sonographic prenatal diagnosis of congenital anomalies. In 40 fetuses (not consecutive cases) with an abnormality diagnosed with ultrasound, additional MR imaging was performed. The basic sequence was a T2-weighted single-shot half Fourier (HASTE) technique. Head, neck, spinal, thoracic, urogenital, and abdominal fetal pathologies were found. This retrospective, observational study compared MR imaging findings with ultrasonographic findings regarding detection, topography, and etiology of the pathology. The MR findings were evaluated as superior, equal to, or inferior compared with US, in consent with the referring gynecologists. The role of these findings in relation to pregnancy management was studied and compared with postnatal follow-up in 30 of 40 babies. Fetal MRI technique was successful in 36 of 39 examinations and provided additional information in 21 of 40 fetuses (one twin pregnancy with two members to evaluate). More precise anatomy and location of fetal pathology (20 of 40 cases) and additional etiologic information (8 of 40 cases) were substantial advantages in cerebrospinal abnormalities [ventriculomegaly, encephalocele, vein of Galen malformation, callosal malformations, meningo(myelo)cele], in retroperitoneal abnormalities (lymphangioma, renal agenesis, multicystic renal dysplasia), and in neck/thoracic pathology [cervical cystic teratoma, congenital hernia diaphragmatica, congenital cystic adenomatoid lung malformation (CCAM)]. This improved parental counseling and pregnancy management in 15 pregnancies. In 3 cases, prenatal MRI findings did not correlate with prenatal ultrasonographic findings or neonatal diagnosis. The MRI provided a more detailed description and insight into fetal anatomy, pathology, and etiology in the vast majority of these selected cases. This improved prenatal parental counseling and postnatal therapeutic planning.

Adult↗
PubMed2003

Assessment of myocardial viability in a porcine model of chronic coronary artery stenosis with dual dose dobutamine magnetic resonance imaging.

In a non-surgical porcine coronary stenosis model resulting in chronic left ventricle dysfunction, we aimed in this study to evaluate the potential of magnetic resonance imaging (MRI) to distinguish dysfunctional but viable from necrotic myocardium by using multiple levels of dobutamine inotropic stimulation during a cine MRI protocol (F.P. van Rugge et al. Circulation 1994; 90: 127-138). We compared our results with histopathology. We were able to demonstrate a biphasic effect at increasing doses of dobutamine in a subgroup of animals with a high-grade coronary stenosis, while in another subgroup the coronary stenosis produced a chronic myocardial infarction, in which no functional recovery could be obtained. In this experimental protocol, dual dose dobutamine MRI proved to be an accurate and reproducible technique to perform viability studies in chronic obstructive coronary artery disease. It permits distinguishing chronic ischemic, but viable myocardium from infarcted tissue. The detection of chronically underperfused but potentially salvageable myocardium is of significant clinical importance since it may aid in determining which patients are eligible for revascularization.

Animals↗
PubMed2002

Patient acceptance for CT colonography: what is the real issue?

The aim of this study was to evaluate the discomfort associated with CT colonography compared with colonoscopy and bowel purgation cleansing, and to evaluate patient preference between CT colonography and colonoscopy. In a total of 124 patients, scheduled for multidetector virtual CT colonography and diagnostic colonoscopy, patient acceptance and future preference were assessed during the different steps of the procedure (colon preparation, CT examination, and conventional colonoscopy). Patients who described contradictory findings between the degree of discomfort and their preference regarding follow-up examinations were retrospectively reinterviewed regarding the reason for this discrepancy. Colonoscopy was graded slightly more uncomfortable than virtual CT colonography, but the preparation was clearly the most uncomfortable part of the procedure. Concerning their preference regarding follow-up examinations, 71% of the patients preferred virtual CT colonography, 24% preferred colonoscopy, and 5% had no preference. Twenty-eight percent of the patients preferred virtual CT colonography despite that they thought it was equally or even more uncomfortable than colonoscopy. This was mainly due to the faster procedure (17 patients), the lower physical challenge (14 patients), and the lack of sedation (12 patients) of virtual CT colonography. Factors other than the discomfort related to the examinations play an important role in the patient's preference for virtual CT colonography, namely the faster procedure, the lower physical challenge, and the lack of sedation. Since the preparation plays a major decisive factor in the patient acceptance of virtual CT colonography, more attention should be given to fecal tagging.

Adult↗
PubMed2001

Oral creatine supplementation facilitates the rehabilitation of disuse atrophy and alters the expression of muscle myogenic factors in humans.

1. We investigated the effect of oral creatine supplementation during leg immobilization and rehabilitation on muscle volume and function, and on myogenic transcription factor expression in human subjects. 2. A double-blind trial was performed in young healthy volunteers (n = 22). A cast was used to immobilize the right leg for 2 weeks. Thereafter the subjects participated in a knee-extension rehabilitation programme (3 sessions x week(-1), 10 weeks). Half of the subjects received creatine monohydrate (CR; from 20 g down to 5 g daily), whilst the others ingested placebo (P; maltodextrin). 3. Before and after immobilization, and after 3 and 10 weeks of rehabilitation training, the cross-sectional area (CSA) of the quadriceps muscle was assessed by NMR imaging. In addition, an isokinetic dynamometer was used to measure maximal knee-extension power (Wmax), and needle biopsy samples taken from the vastus lateralis muscle were examined to asses expression of the myogenic transcription factors MyoD, myogenin, Myf5, and MRF4, and muscle fibre diameters. 4. Immobilization decreased quadriceps muscle CSA (approximately 10 %) and Wmax (approximately 25 %) by the same magnitude in both groups. During rehabilitation, CSA and Wmax recovered at a faster rate in CR than in P (P < 0.05 for both parameters). Immobilization changed myogenic factor protein expression in neither P nor CR. However, after rehabilitation myogenin protein expression was increased in P but not in CR (P < 0.05), whilst MRF4 protein expression was increased in CR but not in P (P < 0.05). In addition, the change in MRF4 expression was correlated with the change in mean muscle fibre diameter (r = 0.73, P < 0.05). 5. It is concluded that oral creatine supplementation stimulates muscle hypertrophy during rehabilitative strength training. This effect may be mediated by a creatine-induced change in MRF4 and myogenin expression.

Adenosine Triphosphate↗
PubMed2001

Radiofrequency ablation for eradication of pulmonary tumor in rabbits.

BACKGROUND: Radiofrequency ablation (RFA) has emerged as an alternative for surgery in clinical oncology. This animal experiment was conducted to evaluate the feasibility of RFA in the treatment of pulmonary tumor. METHODS: Eighteen rabbits with pulmonary implantation of VX2 tumors were divided into two groups. Group A (n = 12) was treated with RFA by using a cooled-tip electrode technique. Group B (n = 6) received sham operation. The therapeutic efficacy was evaluated by survival rate, magnetic resonance imaging (MRI), postmortem microangiography, and histology. RESULTS: All animals in group B died within 3 months after tumor implantation. Tumor eradication was achieved in 9 of 12 rabbits (75.0%) in group A, of which 4 rabbits survived longer than 3 months free of disease and another 5 rabbits were found free of viable tumor when sacrificed. One rabbit was subjected to incomplete tumor ablation and two rabbits suffered from local tumor relapse and/or lung metastasis. The 3-month survival rate of RFA-treated rabbits was significantly higher (P < 0.01) than that of control rabbits. The typical MRI appearances of the acute RFA lesion consisted of five characteristic concentric zones, which corresponded to central needle track (zone A), tumor coagulation (zone B), pulmonary parenchyma coagulation (zone C), peripheral hemorrhage (zone D), and inflammatory layer (zone E) on histology. CONCLUSIONS: Eradication of pulmonary tumor could be achieved with current RFA technique in rabbits. MRI is a useful modality for assessment of lung tumor ablation.

Angiography↗
PubMed2001

Intracoronary delivery of Gd-DTPA and Gadophrin-2 for determination of myocardial viability with MR imaging.

The aim of this study was to compare intracoronary (i.c.) administration of Gadophrin-2, a necrosis-avid contrast agent (NACA), and nonspecific agent Gd-DTPA for determination of myocardial viability (MV) in acute myocardial infarction (AMI) with MRI. Reperfused AMI was induced in 12 dogs by transcatheter balloon occlusion of coronary artery. In 6 dogs each, Gd-DTPA at 0.1 mmol/kg or Gadophrin-2 at 0.005 mmol/kg was administered into coronary artery by fast bolus (n = 3) or slow infusion (n = 3). Serial ECG-triggered cardiac MRI of T1-weighted segmented turbo fast low-angle shot (FLASH) sequence was conducted and compared with triphenyltetrazolium chloride (TTC) histochemical staining. The contrast ratio and infarct size were quantified and analysed statistically. No cardiovascular side effects were found with local delivery of both agents. After i.c. administration, Gadophrin-2 induced a strong (CR > or = 1.78) and persistent (> or = 10 h) contrast enhancement of infarcted region. The infarct size defined with Gadophrin-2 was almost identical to that with TTC staining throughout the postcontrast period. With a dose 20 times higher, Gd-DTPA also strongly enhanced infarct-to-normal contrast; however, the enhancement diminished with time, i.e. from early strong to later faint enhancement and eventual loss of contrast. The delineated infarct size was also unstable, i.e. from early overestimation to later underestimation and eventual disappearance of the enhanced infarct. In combination with PTCA procedure, i.c. administration of MRI contrast agents may prove useful for post-procedure verification of diagnosis. The NACA-enhanced MRI may serve as an in vivo surrogate of postmortem histochemical staining for determination of MV. Although applicable in clinical setting, cardiac MRI with nonspecific Gd-DTPA is less reliable and should be performed within less than 1 h after contrast.

Animals↗
PubMed2001

Radiofrequency ablation for eradication of renal tumor in a rabbit model by using a cooled-tip electrode technique.

BACKGROUND: Radiofrequency ablation (RFA) has emerged as a potential alternative for surgery in clinical oncology. This animal experiment was conducted to evaluate the feasibility of RFA in the treatment of renal tumor. METHODS: Eighteen rabbits with renal implantation of VX2 tumors were divided into two groups. Group A (n = 12) was treated with RFA by using a cooled-tip RF system at 30 W for 80 to 180 seconds. Group B (n = 6) received a sham operation. The therapeutic efficacy was evaluated by survival rate, magnetic resonance imaging (MRI), and histology. RESULTS: All animals in group B died within 3 months after tumor implantation. Total tumor eradication was achieved in 10 of 12 rabbits (83.3%) in group A, of which 5 rabbits survived longer than 6 months (absolute eradication) and another 5 rabbits were found free of viable tumor when killed (relative eradication). Two rabbits experienced local tumor relapse, lung metastasis, or both. Six-month survival rate of RFA-treated rabbits was significantly higher (P < .01) than that of control rabbits. The typical MRI appearances of the acute RFA lesion consisted of five characteristic concentric zones, which corresponded to central needle track (zone A), tumor coagulation (zone B), renal tissue coagulation (zone C), peripheral hemorrhage (zone D), and inflammatory layer (zone E) on histology. CONCLUSIONS: RFA may become a promising therapy for the treatment of renal tumor. MRI is a useful modality for assessment of renal tumor ablation.

Animals↗
PubMed2001

Basic principles of MRA.

Two types of MR angiography techniques are used in the radiological practice for neurovascular applications: flow based techniques and ultrafast contrast enhanced acquisitions. Both techniques have their specific advantages and limitations. Whereas flow based techniques can be run on most MR scanners, high quality contrast enhanced studies require a state-of-the-art system with high slew rates and dedicated tools to match bolus passage and MR scanning. In this text, we focus on the physical acquisition principles and we illustrate the different phenomena in clinical examples. Numerous studies have proven the clinical applications for the 2 acquisition strategies. So far, an understanding of the basic physics remains necessary to explain occasional artefacts: MR angiography techniques are not yet fully robust. Further optimizations of the current approaches can be expected as there is still a need to improve image quality.

Humans↗
PubMed2001

Graft dilation after redo surgery for aneurysm formation following patch angioplasty for aortic coarctation.

OBJECTIVES: Aneurysm formation after patch angioplasty for aortic coarctation is a frequent and potentially lethal complication, necessitating surgical reintervention. Although several mechanisms have been postulated, flow disturbance in a concomitant hypoplastic transverse aortic arch most likely contributes to the aneurysm formation. The outcome of the grafts after redo surgery, however, is unknown. The purpose of this study was to evaluate the outcome of the inserted graft in patients with surgery for aneurysm formation following patch angioplasty for coarctation of the aorta. METHODS: In 16 patients redo surgery was performed for aneurysm formation (diameter: 47.1+/-11.9 cm) (mean+/-SD), 12.7+/-2.1 years after the initial patch angioplasty. All patients had a concomitant arch hypoplasia. They were treated by insertion of a Dacron Gelseal graft (16-30 mm), but the associated hypoplastic arch segment was left untouched. To evaluate the evolution of the new graft, patients were followed by means of magnetic resonance (MR) imaging. RESULTS: The immediate postoperative outcome was uneventful in 12 patients. Four patients, however, suffered from a recurrent nerve paralysis and one of them of a spinal cord transection. The mean follow-up time was 54.1+/-17.9 months during which 59 magnetic resonance studies were performed. The number of MR studies per patient ranged from two to seven. The graft diameter increased significantly with 56+/-18%, range 20-82 (P<0.0001). This widening was most pronounced within the first year after surgery (43+/-16%, range 5-67) (P<0.0001). CONCLUSIONS: Flow acceleration caused by an even mild hypoplastic transverse arch can put excessive strain on the distal part of the aortic arch. This can lead not only to aneurysm formation after patch angioplasty but also to excessive dilation of the Dacron Gelseal graft. At intermediate long-term follow-up, however, a stabilization of the graft dilation is observed.

Adolescent↗
PubMed2000

Role of magnetic resonance in the diagnosis of subclavian steal syndrome.

Subclavian steal syndrome (SSS) is a condition secondary to an occlusion in the proximal subclavian artery, in which the blood supply to the arm is sustained by reversal of flow in the ipsilateral vertebral artery. We describe two similar cases of SSS due to a right aortic arch with isolated left subclavian artery. Diagnosis was made with magnetic resonance imaging (MRI) and angiography (MRA), which was confirmed by Doppler ultrasound and X-ray angiography. The exact anatomic relationships of the vascular structures were well demonstrated on contrast-enhanced MRA, while flow reversal was documented on flow-encoded MRI datasets. We conclude that the combination of different MRI modalities forms an accurate and reliable alternative in the diagnostic workup of patients with suspected SSS.

Adolescent↗
PubMed2000

Follow-up of patients with previous treatment for coarctation of the thoracic aorta: comparison between contrast-enhanced MR angiography and fast spin-echo MR imaging.

Regular follow-up is required in patients with previous intervention for coarctation of the aorta to detect recoarctation or aneurysm formation. In this study we describe the findings encountered on routine follow-up exams and we compare the use of contrast-enhanced 3D MR angiography (CE MRA) with fast spin-echo MRI (FSE) to study the thoracic aorta after previous intervention. In 51 consecutive patients previously treated for aortic coarctation, 74 MR studies of the thoracic aorta were performed during a 2-year period using CE MRA and FSE MRI. The thoracic aorta was evaluated for abnormalities of course, caliber, shape, and pathology of side branches. The CE MRA and FSE MRI studies were evaluated side by side by consensus of two reviewers evaluating which MR technique depicted the abnormalities of the thoracic aorta the best. Of 74 exams, six clinically important abnormalities were found: four aneurysms and two restenoses. Two small pseudoaneurysms were missed on the FSE studies. Contrast-enhanced MRA was judged to visualize aortic abnormalities better than FSE (47 of 74 MR studies) especially for the transverse aortic arch, coarctation site, left subclavian artery, and aortic arch configuration. For the ascending aorta and distal descending aorta, CE MRA and FSE performed equally well. Aortic diameters measured at four levels in the first 18 MRI studies showed no significant differences in diameter when measured by FSE or CE MRA (p = not significant). Clinically important abnormalities, such as aneurysm formation and restenosis, can be present years after treatment for aortic coarctation. In the regular follow-up of these patients, CE MRA may provide additional diagnostic information compared with FSE and should be included as part of the routine exam.

Adolescent↗