Appropriate use of personal protective equipment among healthcare workers in public sector hospitals and primary healthcare polyclinics during the SARS outbreak in Singapore.

BACKGROUND: Singapore was affected by an outbreak of severe acute respiratory syndrome (SARS) from 25 February to 31 May 2003, with 238 probable cases and 33 deaths. AIMS: To study usage of personal protective equipment (PPE) among three groups of healthcare workers (HCWs: doctors, nurses, and administrative staff), to determine if the appropriate PPE were used by the different groups and to examine the factors that may determine inappropriate use. METHODS: A self-administered questionnaire survey of 14,554 HCWs in nine healthcare settings, which included tertiary care hospitals, community hospitals, and polyclinics, was carried out in May-July 2003. Only doctors, nurses, and clerical staff were selected for subsequent analysis. RESULTS: A total of 10 236 valid questionnaires were returned (70.3% response); 873 doctors, 4404 nurses, and 921 clerical staff were studied. A total of 32.5% of doctors, 48.7% of nurses, and 77.1% of the administrative staff agreed that paper and/or surgical masks were "useful in protecting from contracting SARS". Among this group, 23.6% of doctors and 42.3% of nurses reported working with SARS patients. The view that a paper and/or surgical mask was adequate protection against SARS was held by 33.3% of doctors and 55.9% of nurses working at the A&E unit, 30.5% of doctors and 49.4% of nurses from medical wards, and 27.5% of doctors and 37.1% of nurses from intensive care units. Factors which predicted for agreement that paper and/or surgical masks were protective against SARS, included HCW's job title, reported contact with SARS patients, area of work, and Impact Events Scale scores. CONCLUSION: A variety of factors determine appropriate use of personal protective equipment by HCWs in the face of a major SARS outbreak.

Adjusting to military life--servicemen with problems coping and their outcomes.

A small proportion of servicemen enlisting for compulsory National Service in Singapore experience problems adjusting to military life. This paper aims to profile the servicemen who experience such problems. There is a paucity of literature addressing this issue internationally and none published locally. Servicemen who were referred to the Psychological Medicine Branch of the Singapore Armed Forces within six months of enlistment were retrospectively studied. In the work year July 1995 to June 1996, 77 cases were seen. The main classes of diagnoses were stress-related disorders, anxiety, mood and psychotic disorders. The main stressor was problems adapting to the military environment. There were 10 cases of parasuicide, significantly less than US Army statistics. At Operationally Ready Date, 20.7% were able to hold a combat vocation, similar to the US Army situation. This paper hopes to document the local figures and act as a reference for evaluating future therapies and policies.

Evaluation of the elderly patient with weakness: an evidence based approach.

Because of the altered physiology of the elderly population, either as a result of aging or as a result of other disease processes, many illnesses may present with features that are either atypical or nonspecific in nature. Difficult and nonspecific complaints such as weakness in an elderly patient must be handled in a judicious, cost-effective, comprehensive, and expeditious manner that benefits both the patient and the emergency department. This article addresses the evaluation of the elderly patient who presents to the ED complaining of weakness.

Hypercarbia-induced changes in cerebral blood volume in the cat: a 1H MRI and intravascular contrast agent study.

Cerebral blood volume changes with arterial carbon dioxide were monitored by proton T1-weighted MR images following administration of the intravascular contrast agent Gd-DTPA labeled with human serum albumin. Without MR contrast, no significant image intensity changes were observed with PaCO2. Following contrast, regional brain image intensities increased significantly over control (0% inspired CO2) in cortical gray, white, and basal ganglia regions with increasing PaCO2 and returned to control intensities upon return to 0% inspired CO2. Imaging of through-plane and in-plane phantoms was performed to assess flow effects. Signal losses of 2 and 6% (relative to no flow) were observed for bulk velocities of 5 mm/s at TE values of 15 ms. An intravascular contrast agent may be useful for MRI monitoring of local cerebral blood volume changes during cerebral perturbations.

Diffusion-weighted MR imaging of extraaxial tumors.

The clinical usefulness of the application of spin-echo diffusion-weighted imaging in the evaluation of extraaxial cysts and epidermoid tumors is demonstrated in a series of 15 patients. Apparent diffusion coefficient (ADC) images based on intravoxel incoherent motion (IVIM) were obtained with a maximum gradient b value = 100 s/mm2. Lesion ADC was qualitatively compared to external phantoms. In all cases, epidermoid tumors revealed reduced ADC values similar to that of normal brain tissue. On the other hand, all cysts had ADC similar to the stationary water phantom. Lesion delineation was improved due to the replacement of normal pulsatile (very high ADC) cisternal CSF. Direct quantitative measurements of ADC using this technique may not be possible due to unavoidable motion artifact.

Orbit, skull base, and pharynx: contrast-enhanced fat suppression MR imaging.

The high signal intensity of fat on T1-weighted magnetic resonance images has limited the utility of gadopentetate dimeglumine in imaging of the extracranial head and neck. Enhancing lesions may be obscured either by proximity to fat or by chemical misregistration artifact. The authors evaluated the role of a gadolinium-enhanced fat suppression imaging technique in the detection of extracranial head and neck abnormalities in 29 patients. These studies were directly compared with conventional pre- and postcontrast T1- and T2-weighted SE sequences. In detecting and defining the extent of abnormalities, fat-suppressed images were superior to non-fat-suppressed gadolinium-enhanced T1-weighted images in the majority of cases (22 of 27 [81%]). Fat-suppressed images were particularly beneficial in the detection of perineural spread of tumor as well as in defining lesions situated within or adjacent to fat-containing areas such as the base of the skull. These findings demonstrate that fat suppression techniques in combination with gadolinium enhancement are of value in extracranial head and neck imaging and should replace conventional postcontrast T1-weighted SE imaging.

Normal and diffusely abnormal myocardium in humans: functional and metabolic characterization with P-31 MR spectroscopy and cine MR imaging.

The current study tested the concept that cine magnetic resonance (MR) imaging and phosphorus-31 MR spectroscopy might be used to provide a comprehensive evaluation of the functional and metabolic status of the myocardium in humans. Thirteen patients with congestive cardiomyopathy and eight healthy volunteers were imaged at 1.5 T with the one-dimensional chemical shift imaging technique for localization of P-31 MR spectroscopy and an electrocardiographically referenced gradient refocused sequence for imaging of the heart. Prominent peaks in the PDE and PME regions were observed in cardiomyopathic patients, but only the former peak was measured. The PCr/beta-ATP peak ratio was not significantly lower in cardiomyopathic patients compared with healthy subjects (1.51 +/- 0.08 vs 1.54 +/- 0.04). The ratios of PDE/PCr (0.80 +/- 0.07 vs 0.54 +/- 0.10) (P less than or equal to .01) and PDE/beta-ATP (1.19 +/- 0.10 vs 0.84 +/- 0.08) (P less than or equal to .05) were significantly higher in patients with dilated cardiomyopathy compared with healthy volunteers. Left ventricular systolic wall thickening was significantly lower and left ventricular peak and end-systolic wall stress and mass were significantly higher in cardiomyopathic patients compared with healthy volunteers. Thus, localized, gated P-31 MR spectroscopy combined with cine MR imaging allowed identification of both abnormal myocardial phosphate metabolism and abnormal ventricular function. While this study suggests that increased myocardial PDEs may be a marker for abnormal myocardium, the sensitivity and specificity of this marker need to be further evaluated.

In vivo human testicular function assessed with P-31 MR spectroscopy.

The clinical feasibility of assessing testicular metabolic integrity with phosphorus-31 magnetic resonance (MR) spectroscopy was investigated in six healthy volunteers and 23 patients with azoospermia. MR spectroscopic findings were compared with sperm count and motility in all patients and with findings at testicular biopsy in 23 patients. Significant differences (P less than .05) were found between the P-31 spectra of normal and azoospermic testicles in the following peak area ratios: phosphomonoester (PM)/beta-adenosine triphosphate, PM/phosphodiester, and inorganic phosphate/PM. In the patients with azoospermia, there were significant differences in these same peak area ratios between patients with primary testicular failure and those with chronic tubular obstruction. Although the differences between these two groups were statistically significant, there was a large overlap in numbers, and therefore a study with a larger patient population will be required. P-31 MR spectroscopy is a sensitive tool for assessment of testicular metabolic integrity and differentiation of normal testicles from those with markedly decreased spermatogenesis.

Diffusion-weighted MR imaging of the brain: value of differentiating between extraaxial cysts and epidermoid tumors.

This study demonstrates the use of diffusion-weighted MR imaging in improving the specificity of the diagnosis of extraaxial brain tumors. Three surgically proved lesions (one arachnoid cyst and two epidermoid tumors) and two nonsurgically proved lesions (arachnoid and ependymal cysts) were evaluated with T1- and T2-weighted spin-echo studies followed by intravoxel incoherent motion (IVIM) MR imaging. The IVIM images of the lesions were displayed as an apparent diffusion coefficient (ADC) image obtained at 0.65 G/cm (maximum gradient b value = 100 sec/mm2) and compared with external oil and water phantoms. The ADC of arachnoid cysts was similar to stationary water whereas the ADC of epidermoid tumors was similar to brain parenchyma, indicating the solid nature and the slower diffusion rate of the epidermoid tumors. Cisternal CSF demonstrated uniformly high ADC, primarily because of bulk flow, which enhanced image contrast. Improved delineation of postsurgical changes was also possible. Our preliminary results show that diffusion-weighted MR imaging can be useful in distinguishing between arachnoid cysts and epidermoid tumors.

Diffusion-weighted MR imaging of the brain: value of differentiating between extraaxial cysts and epidermoid tumors.

This study demonstrates the use of diffusion-weighted MR imaging in improving the specificity of the diagnosis of extraaxial brain tumors. Three surgically proved lesions (one arachnoid cyst and two epidermoid tumors) and two nonsurgically proved lesions (arachnoid and ependymal cysts) were evaluated with T1- and T2-weighted spin-echo studies followed by intravoxel incoherent motion (IVIM) MR imaging. The IVIM images of the lesions were displayed as an apparent diffusion coefficient (ADC) image obtained at 0.65 G/cm (maximum gradient b value = 100 sec/mm2) and compared with external oil and water phantoms. The ADC of arachnoid cysts was similar to stationary water whereas the ADC of epidermoid tumors was similar to brain parenchyma, indicating the solid nature and the slower diffusion rate of the epidermoid tumors. Cisternal CSF demonstrated uniformly high ADC, primarily because of bulk flow, which enhanced image contrast. Improved delineation of postsurgical changes was also possible. Our preliminary results show that diffusion-weighted MR imaging can be useful in distinguishing between arachnoid cysts and epidermoid tumors.

Phosphorus-31 MRS of human testicular function and viability.

The current clinical use of magnetic resonance spectroscopy (MRS) is explored with attention to testicular function and pathology. Magnetic resonance spectroscopy provides insights into metabolic processes that are occurring in vivo. Information on these processes were, until now, only obtained through the use of invasive procedures such as biopsy, with the attendant undesired side effects. Phosphorus-31 (31P) MRS of the testes can provide unique metabolic information noninvasively and may provide clinicians with an alternative to the invasive procedures. The practical applicability of 31P MRS to the study of human infertility and testicular pathologies is described in some very preliminary studies.

Magnetic resonance spectroscopy of the heart. Overview of studies in animals and man.

Magnetic resonance spectroscopy (MRS) has been used effectively in the evaluation of cardiac physiology. Studies have been done at various levels of complexity extending from isolated hearts to man. Correlation of high-energy phosphate compounds with contractile function is achieved by simultaneous or immediate sequential measurement of ventricular contractile function and the phosphorus-31 MR spectra. Studies in isolated hearts have monitored the response to ischemia of normal and hypertrophic hearts and the preservation of myocardial function and high- energy phosphate stores by drugs administered prior to the ischemic event. Regional myocardial ischemia has been evaluated by simultaneous monitoring of myocardial regional segment length by sonomicrometry and regional myocardial 31P MRS in the intact heart of larger animal models. Function and metabolism have been assessed in man by the combined application of cine MRI and 31P MRS acquired with a surface coil.

Acute myocardial ischemia and reperfusion: MR imaging with albumin-Gd-DTPA.

The utility of a macromolecular, intravascular contrast agent, albumin-gadolinium diethylenetriaminepentaacetic acid (DTPA), for the differentiation of acutely ischemic and reperfused myocardium on magnetic resonance (MR) images was investigated. Regional, reversible myocardial ischemia was produced in rats and confirmed. After reperfusion, flow to the compromised myocardial segment returned to baseline. Normal myocardium could not be differentiated from ischemic myocardium on nonenhanced MR images (n = 12). After 5 minutes of myocardial ischemia and after administration of albumin-Gd-DTPA, the ischemic zone involving the free wall of the left ventricle was characterized by the absence of significant enhancement. Normal myocardium appeared homogeneously enhanced (by 145%). This pattern persisted for up to 1 hour of myocardial ischemia. In six rats that underwent myocardial reperfusion after 5 minutes of ischemia, the normal and reperfused myocardium became isointense. Radiotracer studies with albumin-Gd-153-DTPA confirmed the decreased distribution of contrast agent to the ischemic myocardium, possibly due to decreased blood pool or a blocked primary delivery system in the ischemic myocardium.

Magnetic resonance imaging of myocardial infarction using albumin-(Gd-DTPA), a macromolecular blood-volume contrast agent in a rat model.

Magnetic resonance (MR) contrast enhancement of acute myocardial infarction was studied in rats using albumin-(Gd-DTPA), a paramagnetic macromolecule with prolonged intravascular retention after intravenous injection. Histologic examination and distribution measurements of radiolabeled microspheres confirmed induction of regional myocardial infarction after ligation of the left coronary artery. ECG-gated spin-echo images at 2.0 Tesla, employing short, T1-weighted pulse sequence settings, demonstrated time-persistent and significant (P less than .05) enhancement of normal myocardium (66%) and an even greater enhancement of the infarcted area (100%), for as long as 60 minutes after injection of 160 mg/kg albumin-(Gd-DTPA). The contrast difference between normal and infarcted myocardium was increased significantly (P less than .05) after administration of albumin-(Gd-DTPA). The prolonged enhancing effects of albumin-(Gd-DTPA) on MR images are useful for evaluating regional differences in blood volume and capillary integrity between normal and infarcted myocardium.

Comparison of initial biodistribution patterns of Gd-DTPA and albumin-(Gd-DTPA) using rapid spin echo MR imaging.

The initial biodistribution patterns of gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA), an extracellular fluid contrast agent, and human serum albumin, paramagnetically labeled with 19 Gd-DTPA groups and used as an intravascular agent, were compared in the brain, heart, liver, and major mediastinal vessels of rats. Repeated 4 s spin echo images acquired after injection of 0.2 mmol/kg Gd-DTPA demonstrated a maximum enhancement between 15 and 25 s of 57% in brain, 307% in heart, 220% in liver, 83% in subcutaneous tissue, and 380% in slowly flowing blood in mediastinal vascular structures. In the following 55 s there was a continuous decrease (average 45%) in signal intensity in each tissue except brain. Albumin-(Gd-DTPA), injected at a four times lower molar dose (0.045 mmol/kg) with respect to Gd-DTPA, demonstrated maximal enhancement of brain by 34%, heart by 237%, liver by 186%, and blood in mediastinal vessels by 325%. Gadolinium-DTPA, which rapidly diffuses from the small vessels into the interstitial space, was noted to accumulate in solid tissues and subsequently to be partially eliminated within 70 s of administration. Signal enhancement achieved with albumin-(Gd-DTPA) remained at a constant level over the 70 s observation period. These data further support the notion that albumin-(Gd-DTPA), due to its predominantly intravascular distribution, might be applied advantageously for the assessment of perfusion and blood-volume disorders.

Spin-echo fluorine magnetic resonance imaging at 2 T: in vivo spatial distribution of halothane in the rabbit head.

Spin-echo 19F magnetic resonance imaging was performed at 2.0 T to explore the in vivo spatial distribution of halothane in the rabbit head. Because the halothane concentration is low in vivo, and because the measured relaxation times of the 19F resonance peak for halothane were T1 approximately equal to 1.0 sec and T2 approximately equal to 3.5-65 msec, 1-3-h imaging times were required (TR = 1 sec, TE = 9 msec) in order to obtain adequate images with a 64 X 256 raw data matrix and a 20-mm slice thickness. With this technique, halothane was primarily detected in lipophilic regions of the rabbit head, but little or no halothane was observed in brain tissue. Because T2 was shorter in brain tissue than in surrounding fat, a shorter TE than we could obtain is needed for optimal spin-echo imaging of brain halothane.

Contrast-enhancing properties of Gd-DTPA at 2.0 Tesla.

The contrast enhancing properties of Gd-DTPA in various tissues, including myocardium, liver, brain, skeletal muscle, and subcutis were investigated in vivo at 2.0 Tesla. Employing T1-weighted short pulse sequences (TR = 300 msec, TE = 14 msec) signal intensity of myocardium increased by 88%, brain by 19%, liver by 61%, skeletal muscle by 50%, and subcutis by 52% at 2 min after intravenous injection of 0.2 mmol/kg Gd-DTPA in rats. Signal intensity was highest at 2 min after injection and was relatively decreased at 20 min. Tissue intensities had returned to baseline at 60 min. In a separate experiment, fast (4 sec), repeated spin-echo image acquisitions allowed for assessment of the initial, dynamic distribution pattern of Gd-DTPA between 4 sec and 72 sec after intravenous injection. Tissue signal intensities peaked between eight and 16 seconds after injection and slowly decreased thereafter. This study shows that the contrast-enhancing properties of Gd-DTPA can be effectively assessed using T1-weighted short pulse sequences at 2.0 Tesla.

A novel double-surface coil approach to phosphorus-31 spectroscopy: a study of hemispheric brain injury in the rat.

An arrangement of two surface coils was devised to allow phosphorus-31 (31P) NMR spectroscopy of a localized hemispheric brain injury model in the rat. Two elliptical (8 X 12 mm) surface coils are placed parallel to each other (3 mm apart) over each side of the rat head. Spectra are collected from either the normal or the injured side of the head using the appropriate surface coil. A passive detuning method was used to eliminate unwanted coil-coil interactions. 31P imaging results with the two coils on phantoms show excellent isolation (6% signal overlap) between the two coils. The two-coil setup was then used to follow a time course of injury from the hemispheric injury model.

In vivo sodium-23 magnetic resonance surface coil imaging: observing experimental cerebral ischemia in the rat.

Sodium-23 magnetic resonance imaging can be used to detect and assess experimental cerebral ischemia in the rat. An imaging technique utilizing a surface coil is described to produce sodium magnetic resonance images of good quality and resolution within 10 min. A novel method of hemispheric occlusion showed edema in the right brain of the rat head within 3 hr after injury. The edema was especially pronounced by 12 hr with effects in the right brain, eye and surrounding muscle evident.