Abstract:Spiral computed tomography of pulmonary embolism. C.J. Herold. #ERS Journals Ltd 2002. ABSTRACT: Within the last several years, spiral computed tomography angiography (SCTA) of the pulmonary arteries has emerged as a noninvasive angiographic modality for the evaluation of patients with suspected pulmonary embolism (PE). SCTA is based on continuous computed tomography (CT) data acquisition during patient transport through the rotating X-ray tube and detector system, where scanning is performed in the time perio… Show more
“…As well as modulating microvascular tone in skin, NO has been implicated in the modulation of vascular permeability. Again, conflicting results exist on the role of NO in mediation of SP-induced protein extravasation [13, 14, 38, 52, 53, 54, 55]. In our study, a significant reduction of SP-induced protein extravasation was observed.…”
Endogenous neuropeptides released from nociceptors can induce vasodilation and enhanced protein extravasation (neurogenic inflammation). The role of nitric oxide (NO) in the induction of neurogenic inflammation is controversial. In this study, dermal microdialysis was used in awake humans (n = 39) to deliver substance P (SP; 10–7 and 10–6M) or calcitonin gene-related peptide (CGRP; 5 × 10–7M and 2 × 10–6M). Neuropeptide-induced local and axon reflex erythema was assessed by laser Doppler imaging. Total protein concentration in the dialysate was measured to quantify local protein extravasation. The responses were assessed in the absence and the presence of the nitric oxide synthase inhibitor, N-nitro-L-arginine-methyl ester (L-NAME) added to the perfusate at concentrations of 5, 10 or 20 mM. L-NAME (5 mM) applied via the dialysis catheters reduced local blood flow by approximately 30%. In addition, L-NAME inhibited SP-induced vasodilation by about 40% for 10–7M SP and 30% for 10–6M SP (n = 11, p < 0.01). In contrast, CGRP-induced vasodilation was only marginally inhibited by L-NAME. SP, but not CGRP, provoked a dose-dependent increase in protein extravasation. L-NAME (5 mM) inhibited this increase by up to 40% for both SP concentrations used (n = 11, p < 0.01). Higher concentrations of L-NAME did not further reduce SP- or CGRP-induced vasodilation or SP-induced protein extravasation. Exogenously applied SP induces vasodilation and protein extravasation, which is partly NO mediated, whereas CGRP-induced vasodilation appears to be NO independent.
“…As well as modulating microvascular tone in skin, NO has been implicated in the modulation of vascular permeability. Again, conflicting results exist on the role of NO in mediation of SP-induced protein extravasation [13, 14, 38, 52, 53, 54, 55]. In our study, a significant reduction of SP-induced protein extravasation was observed.…”
Endogenous neuropeptides released from nociceptors can induce vasodilation and enhanced protein extravasation (neurogenic inflammation). The role of nitric oxide (NO) in the induction of neurogenic inflammation is controversial. In this study, dermal microdialysis was used in awake humans (n = 39) to deliver substance P (SP; 10–7 and 10–6M) or calcitonin gene-related peptide (CGRP; 5 × 10–7M and 2 × 10–6M). Neuropeptide-induced local and axon reflex erythema was assessed by laser Doppler imaging. Total protein concentration in the dialysate was measured to quantify local protein extravasation. The responses were assessed in the absence and the presence of the nitric oxide synthase inhibitor, N-nitro-L-arginine-methyl ester (L-NAME) added to the perfusate at concentrations of 5, 10 or 20 mM. L-NAME (5 mM) applied via the dialysis catheters reduced local blood flow by approximately 30%. In addition, L-NAME inhibited SP-induced vasodilation by about 40% for 10–7M SP and 30% for 10–6M SP (n = 11, p < 0.01). In contrast, CGRP-induced vasodilation was only marginally inhibited by L-NAME. SP, but not CGRP, provoked a dose-dependent increase in protein extravasation. L-NAME (5 mM) inhibited this increase by up to 40% for both SP concentrations used (n = 11, p < 0.01). Higher concentrations of L-NAME did not further reduce SP- or CGRP-induced vasodilation or SP-induced protein extravasation. Exogenously applied SP induces vasodilation and protein extravasation, which is partly NO mediated, whereas CGRP-induced vasodilation appears to be NO independent.
“…The proportion of spiral CT examinations that give no result because of technical failure, or give an indeterminate result, is variously reported as 2-10% [49,68,101]. Errors can be caused by cardiac [102] or respiratory [49,103] artifacts, too little contrast medium [70,102] or anatomical factors such as hilar nodes [31] or peribronchovascular infi ltration [49,103]. First results from the early 1990s [104,105], admittedly only with acute central PE, indicated a sensitivity of nearly 100% and a specifi city of 96%.…”
Section: Spiral Ct In Comparison With Lpsmentioning
Lung perfusion scintigraphy (LPS) with technetium-99m-labeled macro-aggregates of albumin (Tc-99m-MAA) is well established in the diagnostic of pulmonary embolism (PE). In the last decade, it was shown that single-photon emission computer tomography (SPECT) acquisition of LPS overcame static scintigraphy. Furthermore, there are rare indications for LPS, such as preoperative quantification of regional lung function prior to lung resection or transplantation, optimization of lung cancer radiation therapy, quantification of right-left shunt, planning of intra-arterial chemotherapy, and several rare indications in pediatrics. Moreover, LPS with Tc-99m-MAA is a safe method with low radiation exposure. PE can also be diagnosed by spiral computer tomography (CT), ultrasound, magnetic resonance angiography, or pulmonary angiography (PA, former gold standard). The present review considers all these methods, especially spiral CT, and compares them with LPS with respect to sensitivity and specificity and gives an overview of established and newer publications. It shows that LPS with Tc-99m-MAA represents a diagnostic method of continuing value for PE. In comparison with spiral CT and/or PA, LPS is not to be defeated as mentioned also by the most actual Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) II reports. This applies in particular to chronic or recurring embolisms, whereas currently spiral CT may be of greater value for major or life-threatening embolisms. At present, LPS cannot be replaced by other methods in some applications, such as pediatrics or in the quantification of regional pulmonary function in a preoperative context or prior to radiation therapy. LPS still has a place in the diagnostics of PE and is irreplaceable in several rare indications as described earlier.
“…Leg US may be used in patients with subsegmental PE without central pulmonary artery involvement or in those with a negative spiral CT with leg symptoms, to investigate the presence of a lower limb DVT. It is important to diagnose or exclude presence of DVT in these patients as coexisting thrombus in leg veins can re‐embolize into the lungs 74 …”
Section: Other Imaging Investigationsmentioning
confidence: 99%
“…It is important to diagnose or exclude presence of DVT in these patients as coexisting thrombus in leg veins can re-embolize into the lungs. 74…”
Over the last decade, contrast-enhanced spiral CT has been established as a non-invasive alternative to catheter angiography and is now regarded as the first-line imaging investigation for the diagnosis of pulmonary embolism (PE). The reported sensitivities for the diagnosis of PE of spiral CT vary from 45 to 100% and the specificities vary from 78 to 100%. Prospective outcome studies have shown a high negative predictive value for a single-detector spiral CT for PE. Patients' outcomes were not adversely affected in these studies when anticoagulation was withheld after a negative CT pulmonary angiogram. The main limitation of single-detector spiral CT has been its limited ability to detect isolated subsegmental PE. However, multidetector spiral CT allows evaluation of pulmonary vessels down to sixth-order branches and significantly increases the rate of detection of PE in segmental and subsegmental levels. The interobserver correlations for diagnosis of subsegmental PE with multidetector spiral CT exceed the reproducibility of selective pulmonary angiography. If appropriate equipment is available (multidetector CT), then CT pulmonary angiogram is safe to be used as the first-line imaging investigation for the diagnosis of PE.
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