Exercise hyperpnea: where do we go from here?

Pulmonary ventilation (VE) increases during exercise to meet the demands of increased oxygen consumption (VO2) and CO2 production. Despite numerous studies over the past century, the mechanism mediating exercise hyperpnea remains controversial. Progress has been limited primarily by the incomplete understanding of the complex basic ventilatory control system and by the difficulty of significantly manipulating a single potential pathway while still performing physiologic exercise. Where do we go from here to further study the exercise hyperpnea?     

The nuclear issue: where do we go from here?

The drive for the elimination of nuclear weapons is going badly and there is currently little support from the general public. The United States Nuclear Posture Review incorporates nuclear capability into conventional war planning. The Stockpile Stewardship Program is designed to maintain nuclear weapon capability. The US is planning an essentially new earth-penetrating nuclear weapon and is prepared to test this in the national interest if thought necessary. These policies could stimulate nuclear proliferation by others, do nothing to deter terrorism, promote persisting polarization of the world, are a clear breach of the Non-Proliferation Treaty and rest world security on a continued balance of terror. A renewed mass campaign to counteract all this, on legal and moral grounds in particular, is urgently needed. IPPNW and kindred organizations must restore sanity in our policies and humanity to our actions.     

Does location matter? Prognostic value of single-photon emission computed tomography myocardial perfusion imaging by vascular territory

Background

The location of a myocardial perfusion abnormality frequently affects clinical decision making, especially if the left anterior descending artery (LAD) territory is involved. The purpose of this study was to determine whether the location of abnormalities on single-photon emission computed tomography (SPECT) imaging affects outcomes.

Methods

We retrospectively analyzed 21,294 consecutive patients with known or suspected coronary artery disease who underwent exercise or pharmacological stress SPECT over a 10-year period. Using the ASNC 17-segment model, 2 observers interpreted images with regards to defect severity, size, and reversibility. The summed stress score (SSS) was used in relation to vascular territories [LAD, right coronary artery (RCA), and left circumflex artery (LCx)]. All patients were followed over a mean period of 2.5?±?2?years for cardiac events (cardiac death or non-fatal myocardial infarction).

Results

Of the enrolled patients, 5,676 had single-vessel territory defects with a mean SSS of 4.3?±?2.8. Cardiac event-free survival curves revealed no significant difference between the 3 locations (LAD, RCA, and LCx) (P?=?.235). When compared by mild (2-3), moderate (4-8), or severe (>8) SSS, outcomes between the 3 groups were again similar. There were 2,907 patients with two-vessel territory defects with a mean SSS of 10.8. Outcomes were similar between the following 2 groups: two-vessel with LAD involvement and two-vessel without LAD involvement (P?=?.558).

Conclusion

In patients with single- or two-vessel territory perfusion abnormalities with similar size and severity of perfusion defects, the location of defect did not impact future cardiac events. Location of myocardial perfusion defect on SPECT imaging may not be helpful in clinical decision making.     

Impact of the COVID pandemic on emergency department CT utilization: where do we go from here?

Emergency Radiology - To analyze the impact of the coronavirus disease (COVID) pandemic on emergency department (ED) computed tomography (CT) utilization. A retrospective observational study was...     

201Tl gated single photon emission computed tomographic myocardial perfusion imaging in the assessment of global and regional left ventricular function. Would it be favoured over equilibrium radionuclide angiography?

BACKGROUND: This study investigates the clinical performance of routine 201Tl gated single photon emission computed tomographic (201Tl GSPECT) myocardial perfusion imaging. Equilibrium radionuclide angiography (ERNA) was used as the standard for comparison. METHODS AND RESULTS: One hundred and seventy-two consecutive patients were submitted to both myocardial 201Tl GSPECT imaging, at stress and in redistribution, and ERNA. Left ventricular ejection fractions (LVEF) and regional wall motion were assessed from both stress and redistribution 201Tl GSPECT datasets, and from ERNA. Linear regression analysis showed a good correlation between LVEF calculated by ERNA and 201Tl GSPECT (r=0.73 at stress, r=0.75 in redistribution, P<0.0001). However, the 95% prediction intervals of 201Tl GSPECT LVEF from ERNA LVEF were wide (minimum 35.4% at stress and 33.2% in redistribution). Moreover, a difference in LVEF > or =10% between ERNA and 201Tl GSPECT was found in 26.4% of cases at stress and 28.6% of cases in redistribution. A fair agreement between ERNA and 201Tl GSPECT was found in regional wall motion assessment in segments with normal or mildly reduced tracer uptake (kappa=0.32 at stress and kappa=0.33 in redistribution). In segments with moderately to severely reduced tracer uptake, a moderate agreement was found in regional wall motion assessment between ERNA and 201Tl GSPECT (kappa=0.44 at stress and kappa=0.42 in redistribution). CONCLUSIONS: Left ventricular function may be misinterpreted in a significant proportion of patients if the calculation of LVEF is based on 201Tl GSPECT. Moreover, the evaluation of regional wall motion by 201Tl GSPECT appears unsatisfactory.     

Transient ischemic dilatation ratio derived from myocardial perfusion scintigraphy: What are we looking at?

Background  

Elevated transient ischemic dilatation (TID) ratio during myocardial perfusion imaging (MPI) is described as a marker of severe CAD, even in acquisitions with normal perfusion. This was initiated to explore the effects of stressor type on the TID. Additionally the relation between the TID and other functional parameters, such as end diastolic volume (EDV), end systolic volume (ESV), and left ventricle ejection fraction (LVEF), heart rate (HR), and severity of ischemia, was evaluated.     

Analysis of myocardial perfusion from vasodilator stress computed tomography: Does improvement in image quality by iterative reconstruction lead to improved diagnostic accuracy?

BackgroundIterative reconstruction (IR) in cardiac CT has been shown to improve confidence of interpretation of noninvasive coronary CT angiography (CTA).ObjectiveWe hypothesized that IR would also improve the quality of vasodilator stress coronary CT images acquired with low tube voltage to assess myocardial perfusion and the accuracy of the detection of perfusion abnormalities by using quantitative 3-dimensional (3D) analysis.MethodsWe studied 39 consecutive patients referred for coronary CTA (256-slice scanner; Philips), who underwent additional imaging (100 kV, prospective gating) with regadenoson (0.4 mg; Astellas). Stress images were reconstructed with different algorithms: filtered back projection (FBP) and IR (iDose; Philips). Image quality was quantified by signal-to-noise and contrast-to-noise ratios in the blood pool and the myocardium. Then, FBP and separately IR images were analyzed with custom 3D analysis software to quantitatively detect perfusion defects. Accuracy of detection was compared with perfusion abnormalities predicted by coronary stenosis >50% on coronary CTA.ResultsFive patients with image artifacts were excluded. In the remaining 34 patients, both signal-to-noise and contrast-to-noise ratios increased with IR, indicating improvement in image quality compared with FBP. For 3D perfusion analysis, 10 patients with normal coronary arteries were used as a reference to correct for x-ray attenuation variations in normal myocardium. In the remaining 24 patients, reduced noise levels in the IR images compared with FBP resulted in tighter attenuation distribution and improved detection of perfusion abnormalities.ConclusionIR significantly improves image quality on regadenoson stress CT images acquired with low tube voltage, leading to improved 3D quantitative evaluation of myocardial perfusion.     

Classification, clinical findings and operative treatment of degenerative and posttraumatic shoulder disease: what do we really need to know from an imaging report to establish a treatment strategy?

Successful patient care involves interdisciplinary Cupertino. Images allow an interpretation of a static dimension, but may not be sufficient to develop a surgical treatment strategy, since many shoulder problems have its origin in a dynamic pathology. This article outlines dynamic clinical tests of shoulder pathology, classifies various degenerative and posttraumatic shoulder problems and stresses key facts an imaging report should include in order to plan surgery. This article conveys basic knowledge of those tests and the dynamic background of shoulder pathology. Basic surgical treatment principles are summarised briefly.     

Comparative assessment of rest and post-stress left ventricular volumes and left ventricular ejection fraction on gated myocardial perfusion imaging (MPI) and echocardiography in patients with transient ischaemic dilation on adenosine MPI: Myocardial stunning or subendocardial hypoperfusion?

Background

Transient ischaemic dilation (TID) on myocardial perfusion imaging (MPI) is an important finding, conveying a high risk of subsequent cardiac events. However, the mechanism leading to TID on MPI is not well elucidated. This study aimed to determine if TID is due to true LV cavity dilation and ventricular stunning, or is due to relative subendocardial hypoperfusion.

Methods

31 patients undergoing single-day Tc-99m adenosine sestamibi MPI were recruited. All had routine ECG-gated single-day rest-stress adenosine MPI, with transthoracic echocardiograms (echo) acquired concurrently at rest, and both immediately, and 2?hours, post-stress. Echocardiography was performed using a Vivid-7 (GE). LV volumes and LVEF were quantified blinded to MPI results, using biplane Simpson method on echo, and quantitatively (including TID) with QGS^?, on MPI.

Results

Patients were divided into quartiles for TID, with the top quartile considered TID positive [TID+ 9/31 (TID ratio 1.3?±?0.09)], and TID negative [TID? 22/31 (TID ratio 1.01?±?0.04)]. There was good correlation between resting echo and MPI physical measurements (LVEDV r ²?=?0.79, LVESV r ²?=?0.9, and LVEF r ²?=?0.75). On MPI, a significant drop in LVEF was observed between rest and early stress in the TID+ group (56.6% vs 46.5%, P?<?.002), as well as an increase in both LVESV (62 vs 79?mls, P?<?.0001) and LVEDV (113 vs 131?mls, P?<?.0001). However, no statistically significant change in LVEF, LVESV or LVEDV was identified on concurrent echo imaging (LVEF 57% vs 56%, P?<?.66; LVESV 48 vs 54?mls, P?<?.26; LVEDV 87 vs 97?mls, P?<?.299). No significant change in LVEF or ventricular volumes was noted in the TID? group by either echo or MPI.

Conclusion

Transient dilation of the left ventricle on adenosine MPI is not related to chamber enlargement and myocardial stunning, but is more likely a function of subendocardial hypoperfusion and impaired coronary flow reserve.