PubMed Health⌕ Search

Biomedical subjects

N Howarth

Publications and source records attributed to N Howarth.

At least 19 recordsLinked to original sources
PubMed2003

[Lung embolism in the elderly].

Elderly people have an increased risk of suffering from thrombo-embolic events. Lung embolism is often found as a cause of death in autopsies in elderly people. However, it is unknown whether the increased age is a risk factor per se or whether elderly people suffer more often from co-morbidities associated with a higher thrombo-embolic risk. Immobility is the most important risk factor for thrombo-embolic events. Other risk factors include trauma, surgery, venous stase, genetic factors (thrombophilia) and a history of past thrombo-embolic events. Although the probability of suffering from a thrombo-embolic event increases with age, it can be difficult to find the correct diagnosis in elderly people: symptoms like dyspnoe or chest pain might be explained by other cardio-pulmonary diseases. In this review, we would like to give an overview about the diagnostic and therapeutic steps in elderly people.

Aged↗
PubMed2002

Pelvic haemophilic pseudotumour: management of a patient with high level of inhibitors.

Haemophilic pseudotumour (HP) is a rare but very serious complication of haemophilia. HP affects mainly patients with severe haemophilia and those who have developed antibodies to factor VIII or factor IX. We report on a 45-year-old man with haemophilia A and high titres of inhibitors who developed an extensive HP with progressive destruction of the right ilium over a period of 12 years. The different therapeutic options (conservative management by replacement therapy, surgical approach, radiotherapy, percutaneous evacuation with secondary refilled cavity and transcatheter arterial embolization) are reviewed.

Bone Diseases↗
PubMed2001

Performance of helical computed tomography in unselected outpatients with suspected pulmonary embolism.

BACKGROUND: Helical computed tomography (CT) is commonly used to diagnose pulmonary embolism, although its operating characteristics have been insufficiently evaluated. OBJECTIVE: To assess the sensitivity and specificity of helical CT in suspected pulmonary embolism. DESIGN: Observational study. SETTING: Emergency department of a teaching and community hospital. PATIENTS: 299 patients with clinically suspected pulmonary embolism and a plasma D -dimer level greater than 500 microgram/L. INTERVENTION: Pulmonary embolism was established by using a validated algorithm that included clinical assessment, lower-limb compression ultrasonography, lung scanning, and pulmonary angiography. MEASUREMENTS: Sensitivity, specificity, and likelihood ratios of helical CT and interobserver agreement. Helical CT scans were withheld from clinicians and were read 3 months after acquisition by radiologists blinded to all clinical data. RESULTS: 118 patients (39%) had pulmonary embolism. In 12 patients (4%), 2 of whom had pulmonary embolism, results of helical CT were inconclusive. For patients with conclusive results, sensitivity of helical CT was 70% (95% CI, 62% to 78%) and specificity was 91% (CI, 86% to 95%). Interobserver agreement was high (kappa = 0.823 to 0.902). The false-negative rate was lower for helical CT used after initial negative results on ultrasonography than for helical CT alone (21% vs. 30%). Use of helical CT after normal results on initial ultrasonography and nondiagnostic results on lung scanning had a false-negative rate of only 5% and a false-positive rate of only 7%. CONCLUSION: Helical CT should not be used alone for suspected pulmonary embolism but could replace angiography in combined strategies that include ultrasonography and lung scanning.

Adult↗
PubMed2001

Fungal infections in transplant recipients.

Fungi are ubiquitous and the respiratory tract is exposed to aerosolized spores of both fungi that are "pathogenic" even in the normal host, such as Cryptococus neoformans, and those that are "opportunistic", such as Candida and Aspergillus species, among others. Although these latter species may occasionally form fungal balls or induce allergic phenomena in the normal host, they produce more invasive diseases in immunosuppressed patients. Among these diseases, pseudomembranous aspergillosis has recently been described. The diagnostic approach to these entities, and, in particular, the thin dividing line between colonization and infection are addressed, along with the diagnostic value of the various procedures. New prophylactic regimens are reviewed such as the possibility of using amphotericin aerosols in combination with systemic azole administration. The authors would emphasize the importance of restoring lung defences by not only decreasing immunosuppressive regimens but also considering the use of newly available recombinant cytokines such as growth factors, to reduce neutropenia, for instance, in addition to antifungal drugs when infection is diagnosed. However, immunomodulation procedures are far from being well established.

Humans↗
PubMed1999

Prospective comparison of MR lung perfusion and lung scintigraphy.

This study attempted to assess the accuracy and potential of lung magnetic resonance (MR) perfusion imaging compared with perfusion scintigraphy in the evaluation of patients with suspected lung perfusion defects. The technique, which uses an inversion recovery turbo-FLASH sequence with ultra-short TE (1.4 msec), was tested in 24 patients suspected clinically of having acute pulmonary embolism (n = 19) and in patients with severe pulmonary emphysema (n = 5). Perfusion lung scintigraphy was performed within 48 hours prior to the MRI examination in both groups of patients. The dynamic study was acquired in the coronal plane and consisted of 10 images of 6 slices (a total of 60 images per series). Gadopentetate dimeglumine (0.1 mmol/kg) was manually injected as a compact bolus during the acquisition of the first image. Three senior radiologists reviewed all unprocessed two-dimensional coronal sections. They were blinded to clinical data and other imaging modalities. For the three observers, the average sensitivity and specificity of MR were 69% and 91%, respectively. The overall agreement between MR and scintigraphy appears to be good, with a good correlation between the two modalities (kappa = 0.63). However, the data showed variability depending on the location of the perfusion defect, with higher accuracy in the upper lobes. The agreement between MR perfusion and scintigraphy appears to be moderate in the left inferior lobe (kappa = 0.48). The data showed an overall good interobserver agreement (kappa = 0.66). MR perfusion of the lung is a promising technique in detecting lung perfusion defects.

Adult↗
PubMed1999

Quantification of myocardial perfusion with FAST sequence and Gd bolus in patients with normal cardiac function.

The present study reports on a new calibration of the magnetic resonance imaging (MRI) signal intensity of a fast gradient-echo sequence used for in vivo myocardial perfusion quantification in patients. The signal from a FAST sequence preceded by a arrhythmia-insensitive magnetization preparation was calibrated in vitro using tubes filled with various gadolinium (Gd) solutions. Single short-axis views of the heart were obtained in patients (n = 10) with normal cardiac function. Myocardial and blood signal intensity were converted to concentration of Gd according to the in vitro calibration curve and fitted by a one-compartment model. K1 [first-order transfer constant from the blood to the myocardium for the gadolinium-diethylenetriamine-pentaacetic acid (Gd-DTPA)] and Vd (distribution volume of Gd-DTPA in myocardium) obtained from the fit of the MRI-derived perfusion curves were 0.72+/-0.22 (mL/min/g) and 15.3+/-5.22%. These results were in agreement with previous observations on animals and demonstrated that a reliable measurement of myocardial perfusion can be obtained by MRI in patients with an in vitro calibration procedure.

Calibration↗
PubMed1999

Management of focal nodular hyperplasia and hepatocellular adenoma.

Hepatocellular adenoma and focal nodular hyperplasia are two benign hepatic tumors which are mainly detected in healthy young women. Hepatocellular adenoma is an indication for surgery due to the risk of haemorrhage and malignant transformation. By contrast, focal nodular hyperplasia should be managed conservatively. However, precise diagnosis of these benign liver tumors remains difficult and sometimes impossible, despite new imaging techniques. Because of the risk of diagnostic error, resection or large biopsies of presumed liver tumors should be performed in young women (and a fortiori in men and older patients in whom focal nodular hyperplasia is less prevalent) when the diagnosis of focal nodular hyperplasia is not firmly established. The risk of liver surgery in young patients with normal liver parenchyma is, in the opinion of the authors, lower than the risk of a mistaken diagnosis.

Adenoma, Liver Cell↗
PubMed1999

Contrast-enhanced helical CT for pulmonary embolism detection: inter- and intraobserver agreement among radiologists with variable experience.

OBJECTIVE: The objective of this study was to evaluate inter- and intraobserver agreement in the diagnosis of central pulmonary embolism using contrast-enhanced helical CT among observers with variable experience in the interpretation of pulmonary CT angiograms. MATERIALS AND METHODS: Helical CT angiograms of 60 patients clinically suspected of having pulmonary embolism were analyzed retrospectively and independently by two chest radiologists, one cardiovascular radiologist, and three general radiologists. The films were rated a second time by the chest radiologists to assess intraobserver variability. Findings for pulmonary embolism were categorized as positive, negative, or indeterminate at the main, lobar, and segmental pulmonary artery levels. RESULTS: The observers interpreted 19-21 CT angiograms as positive for pulmonary embolism (mean, 19.7) and one to six as indeterminate (mean, 3.2). Agreement occurred among all observers in 50 patients (83.3%), among five observers in six patients (10.0%), among four observers in three patients (5.0%), and among three observers in one patient (1.7%). Interobserver agreement was very good (kappa, .85) for the diagnosis of pulmonary embolism on a per-patient basis. Agreement on a per-artery basis for all arteries was moderate (66%; kappa, .56); for lobar arteries was good (83%; kappa, .75); and for segmental arteries was moderate (57%; kappa, .47). Mean intraobserver agreement on a per-patient basis was very good (93%; kappa, .87). CONCLUSION: Inter- and intraobserver agreement in the diagnosis of pulmonary embolism with helical CT is very good despite a wide variety of experience among radiologists.

Adult↗
PubMed1998

Case of successful percutaneous stenting of an in situ gastroepiploic-coronary bypass graft.

The in situ or free gastroepiploic artery (GEA) is being used as an arterial conduit for coronary artery bypass surgery (CABG). The recent rapid improvements in stent manufacture, particularly their profile and flexibility, and related equipment, have helped reduce complications of coronary angioplasty. We describe one case of successful stenting of an in situ GEA-posterior descending artery graft. Stenting of an in situ GEA graft may avoid an incomplete result of angioplasty with possible restenosis or the need for multiple surgical revascularization. The use of stents in GEA grafts with 6 Fr soft guiding catheters can be encouraged.

Angina, Unstable↗
PubMed1998

Intrapulmonary lesions: percutaneous automated biopsy with a detachable, 18-gauge, coaxial cutting needle.

PURPOSE: To evaluate a lung biopsy technique in which a detachable, 18-gauge, coaxial guide around a central notched stylet is used as a cutting needle. MATERIALS AND METHODS: The records of 89 consecutive patients (41 women, 48 men; aged 21-86 years) who underwent coaxial percutaneous core biopsy of 91 lung lesions that required needle passage through normal lung tissue (mean lesion size, 33.6 mm; range, 9-80 mm) were studied. Detachable, 18-gauge, coaxial automated cutting needles were used. RESULTS: The mean number of needle passes was 2.5 (range, 1-4). All biopsies yielded sufficient tissue for histopathologic (n = 91) and, if necessary, bacteriologic (n = 12) evaluation (mean core length, 5 mm; range, 1-15 mm). Eighty-nine lesions had definitive diagnoses. Seventy-five lesions were proved to be malignant; seventy (93%) could be accurately diagnosed with coaxial percutaneous core biopsy samples. Fourteen lesions were proved to be benign; 10 (71%) were specifically diagnosed with biopsy samples. Among the 91 biopsies, the overall diagnostic accuracy was 88% (80 of 91 lesions). A pneumothorax occurred in 31 cases (34%), three (3%) of which necessitated placement of a chest tube. Postbiopsy hemoptysis occurred and resolved spontaneously in nine cases (10%). CONCLUSION: This technique provides a core biopsy specimen without the need for an on-site cytopathologist during the procedure. It has a high diagnostic accuracy and an acceptable rate of complications.

Adult↗
PubMed1998

Expiratory CT scans for chronic airway disease: correlation with pulmonary function test results.

OBJECTIVE: The purpose of our study was to correlate findings on expiratory CT scans with results of pulmonary function tests (PFTs) and to determine whether these techniques may be complementary in assessing airway obstruction. MATERIALS AND METHODS: Seventy-four patients with suspected chronic airway disease and 10 healthy nonsmokers underwent inspiratory and expiratory CT scans and PFTs. An air trapping score, corresponding to the ratio of the cross-sectional air trapping area versus the total cross-sectional lung area on expiratory CT, and a reduction score, representing the change in cross-sectional lung area at inspiration and expiration, were calculated using a quantitative grid. The two scores were then correlated with the results of the PFTs. RESULTS: Expiratory air trapping was seen in 18 (51%) of 35 patients with severe airway obstruction (forced expiratory volume in 1 sec [FEV1]:vital capacity < 80%) (group A), in 21 (72%) of 29 patients with predominantly small airways obstruction (abnormal flow-volume curve and FEV1:vital capacity > or = 80%) (group B1), and in four (40%) of 10 patients with normal PFT results (group B2). Expiratory air trapping was never seen in the 10 healthy subjects. Air trapping scores were 27%, 12%, and 8% for groups A, B1, and B2, respectively, with significant negative correlations with FEV1 (r = -.45), FEV1:vital capacity (r = -.31), and forced expiratory flow at 25% of vital capacity (r = -.57). Reduction scores were 18%, 30%, 35%, and 43%, for the groups A, B1, B2, and the healthy group, respectively, with significant correlations with all the PFT indexes (r = .35 to .66) except total lung capacity. CONCLUSION: Air trapping may permit detection of airway obstruction in patients with clinically suspected chronic airway disease even when PFTs are normal. Furthermore, expiratory CT allows one to calculate a reduction score for a cross-sectional lung area that appears to be better correlated with the degree of airway obstruction measured on PFTs.

Adult↗
PubMed1998

Association of small cell lung cancer and the anti-Hu paraneoplastic syndrome: radiographic and CT findings.

OBJECTIVE: The anti-Hu syndrome (bearing the name of the patient in whom the antibody was first discovered) is characterized by a paraneoplastic encephalomyelitis or sensory neuronopathy and the presence of a specific antibody in the serum or CSF and is associated with lung cancer in most patients who have the syndrome. The objective of this study was to determine the relative merits of chest radiography and CT in the imaging of patients with the anti-Hu syndrome. MATERIALS AND METHODS: Chest radiographic and CT findings of 11 patients with anti-Hu syndrome were reviewed and correlated with results of bronchoscopy, surgery, or autopsy. RESULTS: Ten of the 11 patients had small cell lung cancer; in the remaining patient, no cancer was found. Small cell lung cancer was first revealed on radiographs in one patient and solely on CT in the remaining nine patients with small cell lung cancer. In six of these nine patients, the initial CT findings were positive for lung cancer. Tumor was found on follow-up CT in 4-8 months when initial CT findings were negative. Mediastinal adenopathy was present in all 10 cancer patients. Hilar adenopathy was present in four. Parenchymal involvement was seen in three of the 10 patients with cancer. In two patients, the only CT finding of small cell lung cancer was one mediastinal lymph node of 10 mm in each patient. CONCLUSION: Chest CT should be recommended for patients with anti-Hu syndrome, even when chest radiographic findings are interpreted as normal.

Aged↗
PubMed1997

Dynamic phosphorus-31 spectroscopy after fructose load in experimental biliary liver cirrhosis.

RATIONALE AND OBJECTIVES: The authors investigated the usefulness of dynamic phosphorus-31 magnetic resonance (MR) spectroscopy in the assessment of hepatic function by studying the effect of a fructose load on a rat model of liver cirrhosis. METHODS: In vivo P-31 MR liver spectra of eight rats with bile duct ligature and 10 control rats were obtained every 4.6 minutes before and after intraperitoneal fructose load (10 mmol per kilogram of body weight). RESULTS: In the basal spectra of the experimental group, the phosphomonoester peak was higher than in the control group (P = .026). After the fructose load, the phosphomonoester peak increase and the inorganic phosphate peak decrease were significantly less marked in the experimental group (P = .003). There was a linear correlation between the serum level of bilirubin and the phosphomonoester increase (r = .61, P < .001). CONCLUSION: Dynamic P-31 MR spectroscopy may be useful in the assessment of hepatic function in chronic liver disease.

Analysis of Variance↗
PubMed1994

Measurement of lactate in acutely ischemic rat kidneys using magnetic resonance spectroscopy.

RATIONALE AND OBJECTIVES: Quantification of lactate in the kidney by 1H magnetic resonance spectroscopy (MRS) is a difficult task because of the presence of large amounts of peri-renal fat. When an editing scheme is used to detect lactate that filters out all resonances except lactate, there is no suitable metabolite to serve as an internal standard. In this study, the authors evaluate the potential of MRS to measure the absolute lactate concentration in rat kidneys during acute ischemia using MRS. MATERIALS AND METHODS: The authors propose a method based on a double resonance lactate editing scheme used in combination with the fully relaxed water peak as an internal standard. Experiments were performed on the left kidney rendered ischemic in eight rats. RESULTS: Renal lactate concentrations measured by MRS were compared with values derived from chemical analysis. The mean (+/- standard deviation) renal lactate concentrations measured by MRS and determined chemically were 12 +/- 1.2 umol/g, and 12.94 +/- 1.07 umol/g wet weight, respectively. The coefficient of variation for paired observations was 2.96%, indicating excellent agreement between the two methods used for measuring lactate. DISCUSSION: The study results demonstrate that it is possible to assess the lactate concentration in a rat model of ischemic kidney with MRS and suggest that the total lactate pool is detectable by this method under these experimental conditions.

Animals↗
PubMedDate not supplied

Specificity of SPIO particles for characterization of liver hemangiomas using MRI.

We investigated the specificity of superparamagnetic iron oxide (SPIO)-enhanced T1-weighted spin-echo (SE) magnetic resonance (MR) images for the characterization of liver hemangiomas. When imaging liver hemangiomas, which are the most frequent benign liver tumors, a method with very high specificity is required, which will obviate other studies, follow-up, or invasive diagnostic procedures such as percutaneous biopsy. Eighty-three lesions were examined by MR imaging at 1.5 T before and after intravenous injection of SPIO particles. Lesions were categorized as follows according to the final diagnosis: 37 hemangiomas, nine focal nodular hyperplasias (FNHs), 19 hepatocellular carcinomas (HCCs), and 18 metastases. Their signal intensity values were normalized to muscle and compared. The only lesions showing a significant increase in signal intensity ratio (lesion to muscle) on postcontrast T1-weighted SE images were hemangiomas (p < 0.001). The signal intensity ratio of hemangiomas increased on average by 70%. Based on receiver operating characteristic analysis and using a cutoff level of 50% signal increase, the specificity and sensitivity of SPIO-enhanced MR imaging for the characterization of hemangiomas would be 100% and 70%, respectively. The T1 effect of SPIO particles can help differentiate hemangiomas from other focal liver lesions such as FNHs, HCCs, and metastases and may obviate biopsy. When using SPIO particles for liver imaging, it is useful to add a T1-weighted sequence to T2-weighted images, thereby providing additional information for lesion characterization.

Adult↗
PubMedDate not supplied

Investigation of ethyl carbamate levels in some fermented foods and alcoholic beverages.

An analytical procedure has been developed for the determination of trace amounts of ethyl carbamate in fermented foodstuffs and alcoholic beverages. Concentrations were generally below the 1-5 micrograms/kg detection limit in bread, cheese, yoghurt, beer, gin and vodka. Higher concentrations were found in the other alcoholic beverages examined, which included whisky, fruit brandy, liqueur, wine, sherry and port.

Alcoholic Beverages↗