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Biomedical subjects

T H Falke

Publications and source records attributed to T H Falke.

At least 19 recordsLinked to original sources
PubMed2003

[Retroperitoneal bleeding caused by renal angiomyolipoma].

An 81-year-old woman presented with left-flank pain, anaemia and a fast irregular pulse while using oral anticoagulation. Diagnostic investigation revealed retroperitoneal bleeding caused by a medium-sized renal angiomyolipoma. Angiomyolipoma was also found in the contralateral kidney. No tuberous sclerosis was ascertained. Bleeding stopped after discontinuation of anticoagulant therapy. Renal angiomyolipoma is an uncommon benign tumour which is frequently associated with tuberous sclerosis. Spontaneous retroperitoneal bleeding is a potentially life-threatening complication. This type of tumour is usually found incidentally on radiological examination.

Aged↗
PubMed1996

Computed tomography and granulocyte scintigraphy in active inflammatory bowel disease. Comparison with endoscopy and operative findings.

The accuracy of computed tomography (CT) and [99mTc]HMPAO granulocyte scintigraphy (GS) for detection of bowel localization, inflammatory activity, and complications in acute inflammatory bowel disease (IBD) was prospectively studied in 32 patients. Of each bowel segment, findings on CT and GS were scored by one blinded observer. Findings on operation or endoscopy served as the gold standard. In Crohn's disease (CD, 17 patients), CT detected bowel pathology (sensitivity 71%, specificity 98%), abscesses (sensitivity and specificity 100%), and fistulas (sensitivity 80%, specificity 100%). In CD, GS had a sensitive of 79% and a specificity of 98% for detection of inflammatory activity. The detection of complications with GS was poor. Segmental inflammatory activity correlated with endoscopy-operative findings for CT (r = 0/86, P < 0.0001) and GS (r = 0.86, P < 0.0001). In ulcerative colitis (UC, 15 patients), GS predicted proximal extension of bowel involvement better than CT. In CD, CT is Superior to GS for localization of both active and fibrostenotic bowel disease, and in detection of the abscesses and fistulas. In UC, GS showed proximal extension more accurately than CT.

Acute Disease↗
PubMed1996

Quantification of coronary artery bypass graft flow by magnetic resonance phase velocity mapping.

OBJECTIVES: Determination of the true coronary artery bypass graft function requires quantification of the flow rate within the graft. The purpose of the present study was to assess the feasibility of characterizing and quantifying graft flow by magnetic resonance phase velocity mapping. MATERIALS AND METHODS: Twenty-seven patients with 41 angiographically patent coronary artery bypass grafts underwent electrocardiographically gated magnetic resonance phase velocity mapping. Imaging was performed at 0.6 Tesla using a surface coil. Velocity maps of the bypass grafts were obtained throughout the cardiac cycle with a temporal resolution of 50 ms and a spatial resolution of 1.9 x 1.2 x 5 mm3, allowing calculation of phasic and mean graft flow. RESULTS: Adequate flow measurements were obtained in 84% (41 out of 49) of the grafts. Coronary artery bypass graft flow was characterized by a biphasic pattern with a first peak during systole and a second peak during diastole. Average maximum systolic and diastolic velocities over the cross-section of the grafts were 14 +/- 8 cm/s and 15 +/- 9 cm/s, respectively. Mean coronary artery bypass graft cross-sectional area was 0.28 +/- 0.13 cm2. Mean volume flow was 87 +/- 59 ml/min. CONCLUSION: Flow in coronary artery bypass grafts can be characterized and measured noninvasively by magnetic resonance phase velocity mapping.

Blood Flow Velocity↗
PubMed1996

Oral magnetic particles (ferristene) as a contrast medium in abdominal magnetic resonance imaging.

RATIONALE AND OBJECTIVES: In this phase III study, we evaluated the efficacy and safety of a negative contrast medium, ferristene (oral magnetic particles), among 277 patients undergoing magnetic resonance (MR) imaging of the abdomen. METHODS: Enhanced (800 ml ferristene) MR images were compared with unenhanced MR images in an intraindividual-patient control design. Adverse events were recorded. The examinations were performed on 1.5-T MR systems (T1- and T2-weighted sequences). RESULTS: Ferristene increased the diagnostic information in 50.9% of the patients, particularly in those with abdominal masses, lymphoma, or pancreatic disease. Distribution of ferristene in the stomach, duodenum, jejunum, and ileum was complete or sufficient in 70.5-85% of the studies. In 64% of the patients, we were confident in the MR findings after the use of ferristene, and ferristene disclosed additional findings in 22% of the patients. The incidence of adverse events was 9.0%, but only 3.6% of all patients experienced ferristene-related adverse events (e.g., nausea, vomiting). Most events were mild or moderate in intensity. CONCLUSION: Ferristene was well tolerated, and for 50% of the patients it added useful diagnostic information.

Administration, Oral↗
PubMed1996

Clinical safety and efficacy of iobitridol in urography.

PURPOSE: Evaluation of imaging quality and safety of iobitridol 300 compared to iohexol 300 in urography. MATERIALS AND METHODS: 180 patients were included in an urography multicenter study (3 centers, 60 patients in each). RESULTS: There was no significant difference in either the imaging quality or the clinical safety between the 2 contrast media groups. CONCLUSION: Iobitridol is a safe and efficient contrast agent in urography.

Contrast Media↗
PubMed1995

Magnetic resonance imaging of the pulmonary venous flow pattern in mitral regurgitation. Independence of the investigated vein.

OBJECTIVES: The aim of the present study was two-fold: first, to quantify characteristic parameters of the pulmonary venous flow pattern in patients with mitral regurgitation by using magnetic resonance phase velocity mapping; second, to determine whether this pattern is dependent on the vein being investigated and the direction of the regurgitant jet. BACKGROUND: Echocardiographic findings threw doubt on whether the pulmonary venous flow pattern is independent of the vein being investigated and whether the flow velocities in the pulmonary veins have a linear relationship with the volume flow. SUBJECTS AND METHODS: Flow patterns were assessed in all four pulmonary veins by magnetic resonance velocity mapping in healthy volunteers and in 17 patients with echocardiographically mild and 13 patients with severe regurgitation. RESULTS: No differences were found between the use of velocity or volume flow for characterizing individual curves. The pulmonary venous flow pattern in controls was characterized by six points, a biphasic systolic wave (maximum systolic volume flow: 29 +/- 18 ml.s-1), and end-systolic descent (24 +/- 18 ml.s-1), a biphasic diastolic wave (maximum diastolic volume flow: 69 +/- 22 ml.s-1) and an end-diastolic reversed flow. Reversed end-systolic flow was a characteristic sign of severe regurgitation (-10 +/- 18 ml.s-1). The systolic-to-diastolic flow ratio was lower in severe regurgitation (0.5 +/- 0.6) than in mild regurgitation (1.4 +/- 0.9), P < 0.0001). In severe regurgitation, the normalized time intervals from Q wave to the highest systolic peak and end-systolic descent were of less prolonged duration than in mild regurgitation and controls (P < 0.01). Flow patterns between veins were similar and the median of the correlation coefficients between the curves was the same in patients with or without an eccentric jet, 0.80 and 0.81, respectively. CONCLUSION: Magnetic resonance velocity mapping is helpful in determining and understanding pulmonary venous flow characteristics. It is demonstrated that the pulmonary venous flow pattern is independent of the vein being investigated irrespective of the regurgitant jet direction, and that it is useful in grading mitral regurgitation.

Adult↗
PubMed1995

Computed tomography of the large bowel wall. Choice of slice thickness and intraluminal contrast medium.

RATIONALE AND OBJECTIVES: To determine the relative contribution of slice thickness and intraluminal contrast density to imaging of the large bowel wall. METHODS: The authors used phantom experiments to evaluate the partial volume averaging of 2-, 4-, and 8-mm slices on imaging a single density interface (320/-100 HU) and 5 dual-density interfaces (320/50/-100 HU, 160/50/-100 HU, 0/50/-100 HU, -100/50/100 HU, and -1000/50/100 HU). For the experiments with a dual-density interface, which simulated the bowel wall, the phantom was scanned at an angle 45 degrees to the scan plane. RESULTS: The most accurate display of interfaces was obtained with a slice thickness of 2 mm. When using 8-mm slices, walls can appear to be much thinner or thicker than normal or not even recognizable as a wall depending on the densities in the interface. Adjusting the density of the intraluminal contrast medium to within the range of the mean and window setting will improve the representation of the bowel wall. CONCLUSIONS: Slice thickness has a significant influence on the true representation of the bowel wall using computed tomography. This effect is greater than the effect of the intraluminal contrast medium density.

Contrast Media↗
PubMed1994

Comparative evaluation of diagnostic methods in ovarian carcinoma with emphasis on CT and MRI.

A prospective study was performed in 64 patients suspected of having primary or recurrent ovarian epithelial cancer. Physical examination (PE), ultrasonography (US), computer tomography (CT), and magnetic resonance imaging (MRI) were performed and CA 125 serum levels (CA 125) were determined. This evaluation was followed within 3 weeks by laparotomy, which served with the pathology data as the gold standard. Both CT and MRI were, independently, evaluated by two experienced radiologists. The accuracy in diagnosing ovarian carcinoma of both CT (70 and 91%) and MRI (64 and 88%) in patients suspected of primary and recurrent cancer grouped together differed between the two radiologists, but for each radiologist no difference in overall accuracy between CT and MRI was observed. The accuracy of PE was 64%, of US, 67%, and of CA 125, 72%. At surgery, 132 separate tumor locations were present. With CT, 41 and 69% and with MRI, 44 and 56% of these lesions were recognized by the two radiologists, respectively. This was the case in 27% with PE and 34% with US. We conclude that in our setting MRI had no additional value over CT. The interobserver variability was high for both MRI and CT. MRI and CT are both useful diagnostic methods in the diagnosis of ovarian carcinoma.

Adult↗
PubMed1994

Magnetic resonance imaging or metaiodobenzylguanidine scintigraphy for the demonstration of paragangliomas? Correlations and disparities.

Paragangliomas are tumours arising from paraganglionic tissue dispersed from the base of the skull to the pelvic diaphragm. These tumours produce symptoms by secreting catecholamines (functioning tumours) or by local tumour expansion. They can be part of several hereditary disorders. The introduction of magnetic resonance (MR) imaging and metaiodobenzylguanidine (MIBG) scintigraphy has provided new insights into paragangliomas and has tremendously changed the topographic diagnosis of paragangliomas. Both techniques have proven to be adequate in localising paragangliomas. In this report, the performance of these two noninvasive imaging methods in the examination of paragangliomas is compared and the merits and deficits of the two techniques are discussed. Both techniques produce comparable results in the detection of functioning paragangliomas. MR imaging, however, also demonstrates tumours that do not take up MIBG. MR imaging does not involve the use of ionising radiation and is not hampered by medication. Moreover, MR imaging has a higher spatial resolution. Because of these merits it is concluded that for demonstration of paragangliomas, whole-body MR imaging is the preferred and initial method of investigation. MIBG scintigraphy, on the other hand, continues to be a reliable method for non-invasive detection of functioning paragangliomas. At present it is clearly faster in whole-body imaging than MRI and it is definitely patient-friendly (no claustrophobia). It could be reserved for cases where a strong suspicion of a functioning paraganglioma persists, despite normal MR imaging findings, and for cases where doubt exists about the functional activity of one or more multicentric tumours. MIBG scintigraphy must be used in the evaluation of patients referred for iodine-131 MIBG treatment.

3-Iodobenzylguanidine↗
PubMed1994

Monitoring the effect of chemotherapy in Ewing's sarcoma of bone with MR imaging.

Magnetic resonance (MR) imaging was performed in 26 patients with Ewing's sarcoma of bone preceding and following neoadjuvant chemotherapy, to assess tumour response non-invasively prior to surgery. T1- and T2-weighted spin echo images were obtained. Changes including intra- and extramedullary signal intensities, tumour demarcation, tumour volume and the appearance of residual extramedullary tumour were compared with histopathology of the resected specimens. Reduction of tumour volume was significantly higher in good responders. Other single parameters did not correlate with histologic tumour response. However, when several MR parameters summarized in a classification system were combined, a positive correlation with histopathologic response was found. A limited decrease of tumour volume (< 25%) and/or residual soft tissue mass following chemotherapy correlated with a poor response. An inhomogeneous, well-defined cuff of abnormal tissue encircling the bone and/or radiological disappearance of the soft tissue tumour component following chemotherapy correlated with good response. Twenty-three out of 26 patients were correctly classified by MR as good or poor responders. Minimal residual disease (< 10% of the entire tumour volume), observed histologically, could not be identified with MR imaging. Tumour volume reduction and residual extramedullary tumour, rather than changes of signal intensity, are major features for evaluating the response to chemotherapy in Ewing's sarcoma.

Adolescent↗
PubMed1994

Magnetic resonance imaging of Carney's triad.

Carney's triad, a rare disorder affecting young females, is characterized by the presence of at least two of the three following neoplasms: gastric epithelioid leiomyosarcoma, extra-adrenal paraganglioma, and pulmonary chondroma. Diagnosis and follow-up evaluation of cases of Carney's triad may require an approach that uses a combination of modalities, including magnetic resonance imaging (MRI), metaiodobenzyl-guanidine (MIBG) I 131 scintigraphy, and computed tomography. MRI is as effective as MIBG scintigraphy in detecting functioning paragangliomas. In the evaluation of suspected cases of Carney's triad in which there is clinical and biochemical evidence of a paraganglioma, MRI is the modality of choice for screening and follow-up. We report a case of gastric leiomyosarcoma and extra-adrenal paraganglioma in a young woman whose initial presentation was at 7 years of age. To our knowledge, this is the earliest presentation of this disorder.

Adult↗
PubMed1994

MR diagnosis of paraganglioma of the head and neck: value of contrast enhancement.

OBJECTIVE: Contrast enhancement with gadopentetate dimeglumine has been advocated to increase the efficacy of MR imaging for paragangliomas of the head and neck. However, contrast media are expensive, time-consuming to use, and involve minimal but not negligible risks. The purpose of this study was to determine if the use of contrast material is warranted in patients undergoing MR imaging for the diagnosis of paragangliomas of the head and neck. MATERIALS AND METHODS: Unenhanced MR images were compared with images obtained after administration of gadopentetate dimeglumine in 23 healthy subjects and 37 patients who had a total of 71 tumors. Three combinations of sequences were reviewed independently and in a random order by four observers who had no clinical information. Combination A comprised enhanced and unenhanced T1-weighted sequences, combination B comprised unenhanced T1- and T2-weighted sequences, and combination C was a combination of all sequences. A four-point scale of certainty was used. CT, scintigraphic, angiographic, and surgicopathologic findings were used as the standard of reference. Results were subjected to alternative free-response receiver-operating-characteristic (AFROC) scoring and statistical analysis. RESULTS: The mean areas under the AFROC curve for combinations A, B, and C were 0.761, 0.856, and 0.827, respectively. Mean sensitivity/specificity values after dichotomizing the scoring results were 0.73/0.94, 0.79/0.95, and 0.78/0.94 for combinations A, B, and C, respectively. The performance of combinations B and C did not differ markedly, but both combinations were significantly better than combination A. In a relatively large percentage (36%) of small postoperative tumor residues not detected on unenhanced images, however, gadopentetate dimeglumine allowed detection. CONCLUSION: The results of this study indicate that, in general, the use of gadopentetate dimeglumine is not necessary for the detection of head and neck paragangliomas. The addition of contrast-enhanced imaging does not increase the sensitivity or specificity compared with imaging without enhancement. Only when searching for small postoperative tumor residues is the addition of gadopentetate dimeglumine warranted.

Adult↗
PubMed1993

Gadolinium-DTPA enhanced magnetic resonance imaging of bone cysts in patients with rheumatoid arthritis.

OBJECTIVES: To examine the contents of intraosseous cysts in patients with rheumatoid arthritis (RA) through the signal intensity characteristics on gadolinium-DTPA (Gd-DTPA) enhanced magnetic resonance imaging. METHODS: The hand or foot joints of nine patients with the cystic form of RA (where the initial radiological abnormality consisted of intraosseous cysts without erosions) were imaged before and after intravenous administration of Gd-DTPA. A 0.6 unit, T1 weighted spin echo and T2* weighted gradient echo were used to obtain images in at least two perpendicular planes. RESULTS: Most cysts showed a low signal intensity on the non-enhanced T1 weighted (spin echo) images and a high signal intensity on the T2* weighted (gradient echo) images, consistent with a fluid content. No cyst showed an enhancement of signal intensity on the T1 weighted images after intravenous administration of Gd-DTPA, whereas synovium hyperplasia at the site of bony erosions did show an increased signal intensity after Gd-DTPA. Magnetic resonance imaging detected more cysts (as small as 2 mm) than plain films, and the cysts were located truly intraosseously. In six patients no other joint abnormalities were identified by magnetic resonance imaging; the three other patients also showed, after Gd-DTPA administration, an enhanced synovium at the site of bony erosions. CONCLUSIONS: It is suggested that intraosseous bone cysts in patients with RA do not contain hyperaemic synovial proliferation. The bone cysts in patients with the cystic form of RA may be the only joint abnormality.

Adult↗
PubMed1993

Quantitative assessment of pancreatic function by magnetic resonance in cystic fibrosis.

To determine the value of magnetic resonance imaging in the analysis of pancreatic function in cystic fibrosis, 11 adult cystic fibrosis patients with exocrine pancreatic insufficiency were studied by magnetic resonance and a set of non-invasive tests of exocrine and endocrine pancreatic function. Magnetic resonance imaging, comprising the calculation of intensity ratios (pancreas/liver) of the pancreas on T1 ([SE] TR/TE = 300/20) and T2 weighted ([SE] TR/TE = 2000/50-100)images and the measurement of several dimensions of the pancreas, was compared with the results of the indirect pancreatic function tests. Although magnetic resonance showed the typical morphology of the insufficient pancreas in cystic fibrosis, including atrophy, lobular fatty enlargement and infiltration, it was not related to the quantitative exocrine and endocrine function assessed by indirect pancreatic function tests.

Adult↗
PubMed1992

MRI screening of kindred at risk of developing paragangliomas: support for genomic imprinting in hereditary glomus tumours.

Paragangliomas of the head and neck (glomus tumours) can occur in a hereditary pattern and may be hormonally active as well as being associated with paragangliomas elsewhere. A number of these tumours may be present without symptoms. To detect the presence of subclinical paragangliomas we screened 83 members of a family at risk of developing hereditary paragangliomas using whole body MRI and urinary catecholamine testing. In eight previously diagnosed members, eight known glomus tumours of which one functioning, and two unknown glomus tumours and one unknown pheochromocytoma were present. Six unsuspected members showed ten glomus tumours and one pheochromocytoma. It has been suggested that the manifestation of hereditary glomus tumours is determined by the sex of the transmitting parent. There were no tumours in the descendants of female gene carriers. Comparing the likelihood of inheritance with genomic imprinting versus inheritance without genomic imprinting we found an odds ratio of 23375 in favour of genomic imprinting.

Carotid Body↗