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Biomedical subjects

R Nyman

Publications and source records attributed to R Nyman.

At least 19 recordsLinked to original sources
PubMed2006

Split renal function in patients with suspected renal artery stenosis: a comparison between gamma camera renography and two methods of measurement with computed tomography.

PURPOSE: To validate a method for calculating split renal function from computed tomography (CT) compared with gamma camera renography, and to test a new method for the measurement based on a volume-rendering technique. MATERIAL AND METHODS: Thirty-eight patients, aged 65.7 +/- 11.6 (range 37.8-82.1) years, who had undergone both CT angiography and gamma camera renography for a suspected renal artery stenosis were included in this study. Split renal function was calculated from the CT examinations by measuring area and mean attenuation in the image slices of the kidneys, and also by measuring volume and mean attenuation from a 3D reconstruction of the kidneys. Gamma camera renography with 99mTc-MAG3 with or without captopril enhancement was used as a reference. RESULTS: The 2D CT method had good correlation with renography (r=0.93). Mean difference was 4.7 +/- 3.6 (0-12) percentage points per kidney. There was also excellent correlation between the two CT methods (r=1.00). CONCLUSION: CT is equivalent to renography in determining split renal function, and the measurement from the CT examination can be made more quickly and equally accurately with a 3D technique.

Adult↗
PubMed2006

A prospective comparison of duplex ultrasonography, captopril renography, MRA, and CTA in assessing renal artery stenosis.

PURPOSE: To prospectively compare the diagnostic accuracy of duplex ultrasonography, captopril renography, computed tomography angiography (CTA), and 3D Gd magnetic resonance angiography (MRA) in diagnosing hemodynamically significant renal artery stenosis (RAS). MATERIAL AND METHODS: The standard of reference was measurement of transstenotic pressure gradient. Fifty-eight hypertensive patients with suspicion of RAS were evaluated, when possible, by all five techniques. Sensitivity and specificity to detect RAS were compared for each technique on both a patient and kidney basis. Discrepancies were evaluated separately and classified as borderline, method dependent, or operator dependent. RESULTS: The prevalence of RAS was 77%. The sensitivity/specificity of ultrasonography, captopril renography, CTA, and MRA in detecting kidneys with RAS was 73/71%, 52/63%, 94/62%, and 93/91%, respectively. Ultrasonography had a significantly lower sensitivity than CTA and MRA (P<0.001) but higher than captopril renography (P = 0.013). Borderline RAS was the main cause for discrepancies. CONCLUSION: MRA and CTA were significantly better than duplex ultrasonography and captopril renography in detecting hemodynamically significant RAS. The ultrasonography criteria for RAS based on the evaluation of renal peak systolic velocity and renal/aortic ratio are questionable. Captopril renography cannot be recommended for assessing RAS.

Adult↗
PubMed2006

Remodeling of the thoracic aorta after stent grafting of type B dissection: a Swedish multicenter study.

AIM: Endovascular repair of complicated type B dissections has evolved as a promising alternative to open repair. Previous studies have indicated that continued false lumen flow is a predictor of continued aortic dilatation and risk of rupture during follow-up. This multicenter study was conducted to analyze the postoperative changes of the false lumen after endografting of complicated type B dissections. METHODS: All patients treated with endovascular stent grafts for thoracic type B dissections at 5 major Vascular Centers in Sweden were identified through local databases. Review of charts and all available pre- and postoperative CT scans were performed to identify demographics, indications for repair as well as postoperative changes of the aorta and false lumen. RESULTS: A total of 129 patients treated for type B dissections between 1994 and December 2005 were identified. Median radiological follow-up was 14 months. Fourteen patients died perioperatively leaving 115 patients available for analysis. Seventy-four of these had CT imaging of sufficient quality for morphological analysis. The vast majority of acute patients were treated for rupture or end-organ ischemia whereas most chronic patients were treated for asymptomatic aneurysms. In 80% of patients, the false lumen thrombosed along the stent graft but it remained perfused distal to the stent graft fixation in 50% of patients. Only 5% of patients presented with aortic enlargement of the stent grafted area when adequate proximal sealing was achieved. The distal, uncovered aorta displayed expansion in 16% of patients. CONCLUSIONS: The stent grafted thoracic aorta after type B dissection appears to be stabilized by covering the primary entry site with a stent graft in the majority of both acute and chronic dissections. The uncovered portion of the aorta distal to the stent graft, however, remains at risk of continuous dilatation. Stent grafting for complicated type B thoracic dissections seems to be a treatment option with reasonable morbidity and mortality even though the incidence of severe complications is still significant.

Adult↗
PubMed2005

Renal artery stenosis evaluated with 3D-Gd-magnetic resonance angiography using transstenotic pressure gradient as the standard of reference. A multireader study.

PURPOSE: To evaluate 3D-Gd-magnetic resonance angiography (MRA) in detecting hemodynamically significant renal artery stenosis (RAS). MATERIAL AND METHODS: Thirty patients evaluated for atherosclerotic RAS by MRA and digital subtraction angiography (DSA) were retrospectively included. Standard of reference for hemodynamically significant RAS was a transstenotic gradient of 15 mmHg. DSA visualized 60 main renal arteries and 9 accessory arteries. Pressure gradient measurement (PGM) was available from 61 arteries. Three radiologists evaluated all examinations independently in a blinded fashion. RESULTS: RAS was present in 26 arteries. On MRA, each reader identified 4 of 9 accessory renal arteries, a detection rate of 44%. The three readers correctly classified 22/25/22 of the 26 vessels with a significant gradient as > or =60% RAS and 31/25/32 of the 35 with no significant gradient as < 60% RAS on MRA. Interobserver agreement was substantial. MRA image quality was adequate for RAS evaluations in all patients. ROC curves indicated that MRA is an adequate method for evaluating RAS. When screening for RAS, a 50% diameter reduction cut-off is better than 60%. RAS with 40-80% diameter reductions accounted for 65% of discrepancies. CONCLUSION: MRA is an adequate method for evaluating RAS limited mainly by poor detection rate for accessory renal arteries.

Aged↗
PubMed2002

Distal percutaneous transluminal angioplasty through infrainguinal bypass grafts.

AIM: to evaluate the results of transluminal angioplasty (PTA) performed through infrainguinal bypass grafts for stenotic or occlusive lesions at the distal anastomosis and/or in the runoff arteries. DESIGN: retrospective clinical study. MATERIAL AND METHODS: forty-one patients underwent 57 procedures at the distal anastomosis (n=13), in the runoff arteries (n=32) or at both locations (n=12) at a median of 9.6 months (range, 2-76 months) after infrainguinal bypass grafting. Nineteen procedures were on the popliteal artery, the rest on the crural arteries. Eleven procedures related to occlusions less than 5 cm in length. RESULTS: technical success was achieved in 91%. Primary and primary assisted graft patency rates at 3 years were 32% and 53%, respectively. There were no significant differences in patency rates with regard to the graft material, the type of lesion, the level of PTA, the status of runoff and the use of thrombolysis before PTA. No patients underwent amputation as a direct consequence of failed PTA or graft occlusion. One patient underwent acute surgical intervention due to graft occlusion at the time of attempted PTA. CONCLUSION: the results of PTA at the distal anastomosis and/or in the runoff arteries in limbs with infrainguinal bypass seemed to be inferior to the results of surgical revisions reported in literature. However, as failed PTA did not jeopardise vein-patch angioplasty or jump grafting, it is a reasonable alternative to surgical intervention in selected cases.

Aged↗
PubMed2002

Endovascular approach to treating secondary arterioureteral fistula.

Two patients with the rare entity of arterio-ureteral fistula are presented. Both highlight the predisposing factors of radiation, major surgery in the region, history of vascular surgery and presence of double-J-stent. Both patients presented with the clinical sign of intermittent gross hematuria. Both patients were successfully treated by endovascular intervention using graft covered stent.

Aged↗
PubMed2001

Influence of bone marrow on membrane-guided bone regeneration of segmental long-bone defects in rabbits.

Defects 10 mm long were created in long bone in the diaphysis of both radii of 18 rabbits (test and control side). On the test side, ingrowth of bone marrow into the defects was hindered or delayed by: plugging the opening of the cut bone ends with gutta-percha points (n = 7); plugging with Gelfoam (n = 6); or by removing the bone marrow by flushing with saline (n = 5). The defects on both test and control side were covered with an expanded polytetrafluoroethylene membrane, shaped as a tube. Healing was followed with radiographs for four to five months, after which the animals were killed and ground sections of the areas of the defects were prepared for histological examination. On the control side, nine of 18 animals had complete osseous bridging of the defect, and a small transverse non-mineralised zone remained in the centre of the healed defect in the other animals. This zone consisted of loose connective and cartilagenous tissue as well as connective tissue obviously derived from the outside of the membrane. By preventing or delaying the ingrowth of bone marrow we retarded the regeneration of mineralised bone, particularly in the gutta-percha and flushed bone marrow groups. The principle of guided tissue regeneration may be used to achieve regeneration of extensive long-bone defects. Any attempts to delay or prevent bone marrow ingrowth into the defects did retard regeneration of segmental long-bone defects.

Animals↗
PubMed2001

Investigation of the excluded stomach after Roux-en-Y gastric bypass.

BACKGROUND: One problem with Roux-en-Y gastric bypass (RYGBP) is that it leaves the bypassed segment not readily available for endoscopic or radiographic examinations. MATERIALS AND METHODS: Three males, 50, 54 and 64 years old, suffered from repeated, gastrointestinal bleeding of unknown origin requiring transfusion 1/2, 1 and 7 years after RYGBP. Access to the stomach was obtained by an ultrasound-guided percutaneous gastrostomy. RESULTS: We could perform endoscopy, barium studies and gastric acid output measurements through the gastrostomy. Histological gastritis, low acid output and absence of H. pylori infection were found. CONCLUSION: We were able to exclude severe gastric disease in our patients.

Acute Disease↗
PubMed1999

Imaging of abdominal neuroblastoma in children.

PURPOSE: The aims of the study were: 1) to assess the efficacy of different imaging methods for use prior to treatment; 2) to compare the surgico-histopathologically-based International Neuroblastoma Staging System (INSS) staging with the imaging results; and 3) to suggest a localisation scheme for abdominal neuroblastoma. MATERIAL AND METHODS: Thirty-one children with an abdominal neuroblastoma (median age 2 years), underwent abdominal US, CT of chest and abdomen, MR imaging of abdomen and spine, chest radiography, skeletal survey, radionuclide bone scintigraphy, MIBG scintigraphy, and bone marrow biopsy. RESULTS: In the evaluation of local disease, CT and MR were superior to US. There was no significant difference between CT and MR in assessment of the location or size of the tumour. Evaluation of invasive growth and lymphadenopathy was uncertain irrespective of imaging modality. Intraspinal extension was more distinctly demonstrated with MR. Tissue characterization with CT and MR did not contribute in the assessment of the tumours. Contrast enhancement at CT and MR examinations both improved demarcation between tumour and kidney, and was a necessity for evaluation of vessel encasement with CT. The local disease was best assessed by either CT or MR, while metastatic disease was best revealed by CT, MR, scintigraphy or bone marrow biopsy. CONCLUSION: Imaging may be a valuable basis for clinical assessment and pretreatment staging of abdominal neuroblastoma.

3-Iodobenzylguanidine↗
PubMed1997

Scintigraphy and ultrasonography in differentiating osteomyelitis from bone infarction in sickle cell disease.

PURPOSE: To demonstrate the combined use of scintigraphy and ultrasonography (US) in differentiating osteomyelitis from bone infarction in sickle cell disease. MATERIAL AND METHODS: Two patients with sickle cell disease were examined with a combination of bone, bone marrow, white blood cell and/or gallium scintigraphy and US. RESULTS: The scintigraphic studies demonstrated areas of suspected osteomyelitis at the distal femur in both patients and at the proximal right tibia in one of them. US revealed subperiosteal fluid collections in these areas. Aspiration guided by US established the presence of pus at the femur in both instances, which was successfully treated with the US-guided insertion of a drainage catheter and aspiration only, respectively. Thick blood, due to bone infarction, was aspirated at the tibia. CONCLUSION: The scintigraphic studies were useful in locating all areas of suspected osteomyelitis. The role of US was to confirm the presence of a subperiosteal fluid collection and to guide aspiration, which can show the distinction between a haematoma and an abscess.

Abscess↗
PubMed1997

Diverticulitis of the sigmoid colon. A comparison of CT, colonic enema and laparoscopy.

PURPOSE: To evaluate the use of laparoscopy, CT, colonic enema (CE), and laboratory tests (white blood cell count (WBC), sedimentation rate (SR), and C-reactive protein (CRP) in diagnosing diverticulitis of the sigmoid colon. MATERIAL AND METHODS: The diagnostic methods were prospectively evaluated in 88 patients, 30 of whom were referred for laparoscopy. RESULTS: Fifty-two patients were found to have sigmoid diverticulitis: 20 patients by laparoscopy, 21 by CT, and 11 by CE combined with one positive laboratory test. Laparoscopy proved to be superior to the other diagnostic methods in diagnosing diverticulitis of the sigmoid colon. CT had a high specificity (1.0; 95% CI: 0.92-1.0) but low sensitivity (0.69; 95% CI: 0.56-0.79) in detecting diverticulitis. CE had a higher sensitivity (0.82; 95% CI: 0.71-0.90) but a lower specificity (0.81; 95% CI: 0.67-0.91) than CT. CONCLUSION: CT was the best method for diagnosing abdominal pathology outside the colon. CT can be recommended as the first examination in seriously ill patients where abscesses and other causes of the symptoms than diverticulitis must first be ruled out. Laparoscopy is probably the most accurate method in diagnosing diverticulitis.

Adult↗
PubMed1996

Imaging and compartmental classification of solid pelvic tumours in children.

Thirty-five children aged from 1 day to 16 years (median 5 years) with solid pelvic tumours were investigated with US, CT and MR. All three methods gave similar estimates of tumour size. For defining location of the tumours, the pelvis was divided into three midline compartments (anterior, middle and posterior) and a right and left lateral compartment. CT and MR were accurate and equally reliable in determining the tumour location, US was less accurate. Evaluation of confinement to organ of origin was uncertain, regardless of imaging modality. Tissue characteristics with CT and MR did not contribute to the differentiation of the various tumour types, and contrast medium enhancement did not improve the discrimination. Compartmental localization was equally well assessed by CT and MR and, together with sex, was found to correlate with the tumour type.

Adolescent↗
PubMed1996

Long-term follow-up of residual mediastinal masses in treated Hodgkin's disease using MR imaging.

PURPOSE: Long-term follow-up of residual mediastinal masses in treated Hodgkin's disease using MR imaging. MATERIAL AND METHODS: Ten patients, with substantial residual mediastinal masses of low signal intensity (SI) in the T2-weighted image (T2WI), were reinvestigated with MR 19-79 months after completing treatment of Hodgkin's disease. All patients were in complete remission. RESULTS: During the follow-up period, the masses had decreased in size by 0-95% (median 67%) as compared to their initial post-therapy size. The SI continued to be low in the T2WI and was unaffected by the degree of size reduction. CONCLUSION: It is speculated that these mainly fibrotic residual masses undergo slow degradation of the fibrotic part and/or resorption of remaining inflammatory tissue. It is important to understand the natural, long-term MR imaging changes of these residual masses in order more easily to recognize tumour recurrence or other pathologic conditions.

Adult↗
PubMed1996

Imaging of tuberculosis. II. Abdominal manifestations in 112 patients.

PURPOSE: To describe the radiological findings of tuberculosis (TB) of the abdomen as reflected at our hospital. MATERIAL AND METHODS: The radiological files of 503 patients (referred to our institution mainly because of a clinical suspicion of malignancy, and found to have culture- or biopsy-proven TB) were reviewed in order to analyze the spectrum of the TB manifestations in this group of patients. RESULTS: Abdominal manifestations were found in 112 patients, in 1/3 abdominal disease was the only evidence of TB. More than half of the patients also had chest TB. The most common abdominal TB manifestations were peritonitis and lymph node enlargement, each occurring in about 1/3 of the patients. Also 1/3 had genitourinary TB manifestations. About 1/5 had TB of the liver, spleen or pancreas or in the gastrointestinal tract, respectively. Multiple organ involvement was common. CONCLUSION: The need to consider TB in the differential diagnosis in patients with obscure abdominal symptoms, especially with multiple organ involvement, is stressed.

Adolescent↗
PubMed1996

Imaging of tuberculosis. III. Tuberculosis as a mimicker of brain tumour.

PURPOSE: To show that intracranial tuberculosis (TB) often masquerades as brain tumour. MATERIAL AND METHODS: Forty-six patients with intracranial TB, who after CT at the local hospital were referred for surgery or radiotherapy of brain tumour, are presented. Sometimes the correct diagnosis was first established during surgery for brain tumour. RESULTS: The differentiation between TB and gliomas, meningiomas, metastases, or lymphomas may be impossible from the clinical history and CT findings. Angiography, done in 25 of our cases, often helped by not showing the expected tumour vasculature. MR, performed in 9 patients, helped by demonstrating a layered capsule on T2-weighted images in 4 of the lesions (hypointense rim outside hyperintense rim); the centres of the lesions were of decreased, usually very mixed T2 signal intensity. CONCLUSION: Even in patients with findings typical of brain tumour, TB remains an important differential diagnosis.

Adolescent↗
PubMed1996

Portal vein thrombosis mimicking tumour and causing obstructive jaundice. A case report.

The case of a 28-year-old female patient with portal vein thrombosis mimicking tumour and causing obstructive jaundice is presented. The cavernous-transformed enlarged portal vein, explaining the mass-like lesion in the hepatic hilum on ultrasonography, compressed the extrahepatic bile ducts and caused obstructive jaundice. Endoscopic retrograde cholangiography demonstrated multiple nodular extrinsic indentations of the extrahepatic bile ducts with moderately dilated intrahepatic bile ducts.

Adult↗
PubMed1995

Membrane-guided bone regeneration. Segmental radius defects studied in the rabbit.

We tested the principle of guided tissue regeneration (GTR) for healing segmental long-bone defects. 7 mm (3 animals) or 10 mm (5 animals) long segmental defects were created in the diaphyses of both radii in 8 rabbits. The defect on one side was covered with a barrier membrane of expanded polytetrafluoroethylene membrane shaped as a tube, while the contralateral side with no membrane served as the control. Healing was followed with radiographs obtained repeatedly during a 13- (n 3) or 27- (n 5) week period. Thereafter, the animals were killed and ground sections of the defect sites were prepared for histologic examination. Radiographically, the control sites showed some early subperiosteal callus formation and nonunion of the defects after 6 weeks. The bone ends were rounded off and sealed with cortical bone. No major changes were noted after 6 weeks. At the test sites, subperiosteal bone formation at the bone ends was first observed radiographically at 2 weeks. At 9 weeks, a thin cortical bone bridged the defect along the inner surface of the membrane. Histologically, an interrupted line of thin, cortical bone was observed along the inner surface of the barrier membrane. Fatty bone marrow occupied the central and largest volume of the defect. We conclude that it seems possible to use the principle of GTR to accomplish bone union of segmental long-bone defects.

Animals↗