Rapid serological assays for leptospirosis are of limited value in southern Vietnam.

Leptospirosis, although ubiquitous and potentially lethal, is often not diagnosed. The seroprevalence of anti-Leptospira antibodies and the utility of two rapid tests for the serodiagnosis of the disease were studied in Binh Thuan, an area in southern Vietnam with favourable conditions for Leptospira. In an initial survey, blood samples from 44 patients with undifferentiated fever and 83 healthy subjects were each examined for anti- Leptospira antibodies using three tests: an ELISA; a latex card-agglutination test (Dri Dot); and a lateral-flow assay (LeptoTek Lateral Flow). In the ELISA, samples from 35% of the healthy subjects and 40% of the febrile patients were found to have titres of anti- Leptospira IgM of at least 1:80. Only one of the 13 patients checked again, in ELISA, 3 weeks later, showed the marked increase in IgM titre that is indicative of acute leptospirosis. In the initial survey, although the positive results of the lateral-flow assay, applied to whole blood and serum, showed a good agreement with those of the ELISA (kappa = 0.743), the results of the lateral-flow assay were often indeterminate. The card-agglutination test was more specific. The overall agreement between the results of the rapid tests and those of the ELISA was generally poor. When the samples classified as 'indeterminate' in the lateral-flow assay were considered positive, the maximum kappa-value for this assay applied to whole blood was only 0.512. In conclusion, it appears that high seroprevalences of anti- Leptospira IgM and low incidences of acute leptospirosis limit the diagnostic value of the rapid tests that were investigated. The lateral-flow assay is not specific enough. The card-agglutination test is possibly better but, because of the low incidence, its sensitivity could not be evaluated adequately in the present study.

[Retroperitoneal bleeding caused by renal angiomyolipoma]. / Retroperitoneale bloeding uit een renaal 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.

Deep vein thrombosis as a presenting symptom of congenital interruption of the inferior vena cava.

Infrahepatic interruption of the inferior vena cava is a congenital anomaly, resulting in venous drainage of the lower extremities by way of a compensatory enlarged vena azygos system. We report the case of a 37-year-old male who presented with symptoms of deep vein thrombosis of the entire right lower extremity. A right-sided mediastinal mass on the chest X-ray was mistaken for a haematological malignancy but proved later to represent an enlarged azygos vein. The case illustrates that in a case of deep vein thrombosis, especially in younger patients, interruption of the inferior vena cava should be considered. A right-sided paratracheal mass on the chest X-ray may give a clue in making the correct diagnosis.

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.

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.

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.

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.

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.

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.

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.

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.

CT and MR distinction of adenomas and nonadenomas of the adrenal gland.

OBJECTIVE: Because the distinction between adenomas and nonadenomas of the adrenal gland is essential, we investigated which of the following parameters--size, CT attenuation values, MRI signal intensity ratios on T1- and T2-weighted sequences, calculated T2 relaxation times, or T2 relaxation time ratios--provides better discrimination. MATERIALS AND METHODS: We compared these parameters in 44 adrenal masses of 37 patients by means of the Student t test and receiver operating characteristics (ROC) analyses. RESULTS: Only size, CT attenuation values, and signal intensity ratios on T2-weighted MR images of adenomas showed a significant difference from those of nonadenomas. With use of ROC analysis, CT demonstrated a significantly larger area under the curve compared to size and T2 signal intensity ratios, indicating superior performance. CONCLUSION: We found attenuation values on non-contrast-enhanced CT to be the best method in discriminating adrenal adenomas from nonadenomas. Adrenal masses with CT attenuation values below 15 HU warrant no further investigations.

Imaging features of somatostatinoma: MR, CT, US, and angiography.

OBJECTIVE: The imaging features of somatostatinoma are described in four patients. MATERIALS AND METHODS: Four patients, ranging in age from 24 to 57 years, with somatostatinoma were examined. Ultrasonography (US) and CT were performed in all four patients; MRI and angiography were performed in three patients. RESULTS: Three patients had a tumor in the pancreas and one in the papilla major. In two cases there were metastases in the liver, and one had bone and lymph node metastases. Pancreatic tumor and metastases were equally well detected by CT and MRI. One tumor in the tail of the pancreas was initially missed by US. Pancreatic tumor and metastases were echo poor. Angiography showed one vascular and one avascular tumor in the pancreas. Chronic obstructive pancreatitis was seen on CT and MRI in the patient with the tumor in the papilla major. Angiography and US failed to demonstrate this tumor; CT and MRI showed the tumor in retrospect. Primary tumor and metastases are of low signal intensity on T1-weighted imaging and increased signal intensity on T2-weighted imaging. CONCLUSION: Somatostatin-producing endocrine tumors are mainly located in the pancreas but can also be present in extrapancreatic organs such as the duodenum and papilla of Vater resulting in chronic obstructive pancreatitis. Duodenal somatostatinomas are associated with von Recklinghausen neurofibromatosis. Radiologic and MRI features of somatostatinomas resemble those of other neuroendocrine tumors. Radiological techniques and MRI often fail to demonstrate the tumors in the duodenum. The diagnosis in cases of duodenal localization can be established by endoscopic techniques.

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.

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.

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.

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.