Jonathan C.L. Rodrigues

Is High Blood Pressure Self-Protection for the Brain?

RATIONALEnData from animal models of hypertension indicate that high blood pressure may develop as a vital mechanism to maintain adequate blood flow to the brain. We propose that congenital vascular variants of the posterior cerebral circulation and cerebral hypoperfusion could partially explain the pathogenesis of essential hypertension, which remains enigmatic in 95% of patients.nnnOBJECTIVEnTo evaluate the role of the cerebral circulation in the pathophysiology of hypertension.nnnMETHODS AND RESULTSnWe completed a series of retrospective and mechanistic case-control magnetic resonance imaging and physiological studies in normotensive and hypertensive humans (n=259). Interestingly, in humans with hypertension, we report a higher prevalence of congenital cerebrovascular variants; vertebral artery hypoplasia, and an incomplete posterior circle of Willis, which were coupled with increased cerebral vascular resistance, reduced cerebral blood flow, and a higher incidence of lacunar type infarcts. Causally, cerebral vascular resistance was elevated before the onset of hypertension and elevated sympathetic nerve activity (n=126). Interestingly, untreated hypertensive patients (n=20) had a cerebral blood flow similar to age-matched controls (n=28). However, participants receiving antihypertensive therapy (with blood pressure controlled below target levels) had reduced cerebral perfusion (n=19). Finally, elevated cerebral vascular resistance was a predictor of hypertension, suggesting that it may be a novel prognostic or diagnostic marker (n=126).nnnCONCLUSIONSnOur data indicate that congenital cerebrovascular variants in the posterior circulation and the associated cerebral hypoperfusion may be a factor in triggering hypertension. Therefore, lowering blood pressure may worsen cerebral perfusion in susceptible individuals.

Intravenous contrast medium administration at 128 multidetector row CT pulmonary angiography: bolus tracking versus test bolus and the implications for diagnostic quality and effective dose.

AIMnTo investigate the effects of a test bolus protocol contrast medium administration on diagnostic image quality in computed tomography pulmonary angiography (CTPA).nnnMATERIALS AND METHODSnFifty patients referred for exclusion of pulmonary embolism underwent CTPA using a test bolus protocol CTPA at 120 kVp and were compared with 50 patients undergoing CTPA using a standard bolus-tracking protocol at 120 kVp, via assessment of attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) seen in the pulmonary arteries (PAs). An additional group of 10 non-obese patients who underwent CTPA using a test bolus protocol performed at 100 kVp were also analysed. Mean effective dose was calculated from the dose-length product, using standard conversion factors.nnnRESULTSnThe test bolus protocol showed significantly higher attenuation, SNR, and CNR in the pulmonary vasculature down to the segmental level compared to bolus-tracking CTPA (p < 0.0001). There was no significant difference in effective dose between the test bolus and bolus tracking cohorts. The additional group of test bolus CTPA examinations performed at 100 kVp had a significantly reduced effective dose in comparison to both test bolus CTPA at 120 kVp and bolus-tracking CTPA at 120 kVp (p < 0.005) yet maintained mean PA attenuation to segmental level significantly better than bolus-tracking CTPA performed at 120 kVp and comparable to the test bolus cohort performed at 120 kVp.nnnCONCLUSIONnTest bolus contrast administration should be used as an optimal protocol. Performing test bolus CTPA at 100 kVp, as opposed to 120 kVp, significantly reduces dose without compromising PA attenuation in non-obese subjects.

Musculoskeletal Symptoms Amongst Clinical Radiologists and the Implications of Reporting Environment Ergonomics—A Multicentre Questionnaire Study

This multicentre study aimed to assess compliance of the reporting environment with best ergonomic practice and to determine the prevalence of musculoskeletal symptoms related to working as a radiologist. All 148 radiology trainees and consultants in 10 hospitals across the region were invited to complete a musculoskeletal symptoms and reporting ergonomics questionnaire. Best ergonomic reporting practice was defined, following literature review, as being able to alter the following: monitor, desk, chair and armrest height, chair back support, ambient light, and temperature. The frequency that these facilities were available and how often they were used was determined. One hundred and twenty-three out of 148 (83xa0%) radiologists responded, and 38xa0% reported radiology-associated occupational injury. Lower back discomfort was the commonest radiology associated musculoskeletal symptom (41xa0%). Only 13xa0% of those with occupational injury sought the advice of occupational health. No reporting environments conformed completely to best ergonomic practice. Where certain facilities were available, less than a third of radiologists made personal ergonomic adjustments prior to starting a reporting session. Radiologists who had good self-assessed knowledge of best ergonomic practice had significantly less back discomfort than those with poor self-assessed knowledge (Pu2009<u20090.005). We demonstrated high prevalence of musculoskeletal symptoms amongst radiologists. Poor compliance of the reporting environment with best ergonomic practice, in combination with our other findings of a low level of ergonomic awareness, low rates of making ergonomic adjustments and seeking appropriate help, may be implicated. We hope this study raises awareness of this issue and helps prevent long-term occupational injury amongst radiologists from poor ergonomic practice.

Tube potential can be lowered to 80 kVp in test bolus phase of CT coronary angiography (CTCA) and CT pulmonary angiography (CTPA) to save dose without compromising diagnostic quality

AbstractObjectivesThe purpose of this study was to determine whether performing the test bolus (TB) of computed tomography coronary angiography (CTCA) and computed tomography pulmonary angiography (CTPA) at 80xa0kVp reduces dose without compromising diagnostic quality.MethodsAn 80xa0kVp TB protocol for CTCA and CTPA was retrospectively compared to standard TB protocol (non-obese: 100xa0kVp, obese: 120xa0kVp). CT angiogram parameters were unchanged between cohorts. Thirty-seven consecutive 80xa0kVp TB CTCA images were compared to 53 standard CTCA images. Fifty consecutive CTPAs from each protocol were analysed. Diagnostic quality of the CT angiogram was assessed by: mean attenuation, signal-to-noise ratio (SNR) in the ascending aorta (AA) in CTCA and in the main pulmonary artery (MPA) in CTPA, diagnostic rate, and number of repeated monitoring scans. Mean effective dose was estimated using the dose-length product.ResultsMean TB effective doses were significantly lower (Pu2009<u20090.0001) for 80xa0kVp scans compared to the standard in non-obese CTCA (0.15u2009±u20090.04xa0mSv Vs 0.33u2009±u20090.09xa0mSv), obese CTCA (0.17u2009±u20090.06xa0mSv Vs 0.57u2009±u20090.12xa0mSv), and CTPA patients (0.07u2009±u20090.03xa0mSv Vs 0.15u2009±u20090.06xa0mSv). No difference was demonstrated in mean attenuation, SNR (AA), SNR (MPA), diagnostic rates, or number of repeated monitoring scans between protocols.ConclusionsRoutinely performing TB at 80xa0kVp, regardless of body habitus, in CTCA and CTPA results in a small but significant dose reduction, without compromising CT angiogram diagnostic quality.Key Points• CT coronary angiography is performed to exclude the presence of significant coronary atherosclerosis.n • CT pulmonary angiography is performed to diagnose pulmonary thromboembolism.n • This retrospective study showed dose reduction by performing test bolus at 80xa0kVp.n • Diagnosis can be made with reduced exposure to ionising radiation.

Endovascular closure of thoracic aortic pseudoaneurysms: A combined device occlusion and coil embolization technique in patients unsuitable for surgery or stenting

Objectives n nOur aim was to retrospectively evaluate non-stent graft closure of ascending aortic pseudoaneurysms at our center over a 10-year period, and describe a combined device occlusion and coil embolization technique. n n n nBackground n nAortic pseudoaneurysms (APAs) are a rare complication post cardiothoracic surgery, but can have fatal complications. There is increasing use of percutaneous interventional techniques for occlusion of aortic pseudoaneurysms in patients who are considered unsuitable for surgery. Stent graft deployment may not be possible depending on the specific anatomy and pathology. n n n nMethods and Results n nRetrospective evaluation of the catheter laboratory database was performed at our center and anonymized data was obtained for patients who had nonstent endovascular treatment of APAs. Twelve patients were identified with a mean age of 63u2009±u200916 years. Seven patients had the combined occlusion and embolization technique, only 1/7 (14.3%) died from complications related to APAs. Five patients had occlusion device only, 3/5 (60%) died of complications related to their APA. The mean survival for the patients who had a combination procedure was 33.2±.22.6 months (range, 1u2009−u200960 months), compared to 2.7u2009±u20092.6 months with device closure only (note 2 patients had short follow up of <3 months). n n n nConclusions n nWe evaluate non-stent graft percutaneous closure of APAs in a high-risk patient group and provide data on the use of a novel combined occlusion device and coil embolization technique. We feel this is a viable approach to APA closure in this population but this will require larger clinical studies in the future.

Optimising the imaging plane for right ventricular magnetic resonance volume analysis in adult patients referred for assessment of right ventricular structure and function

Our aim was to evaluate the reproducibility and accuracy of using short‐axis and axial (transaxial) plane for magnetic resonance imaging analysis in adult patients referred for assessment of right ventricular (RV) structure and function.

A completed audit cycle of the lateral scan projection radiograph in CT pulmonary angiography (CTPA); the impact on scan length and radiation dose

AIMnTo investigate the effect of incorporating a lateral scan projection radiograph (topogram) in addition to the standard frontal topogram on excess scan length in computed tomography pulmonary angiography (CTPA) and to quantify the impact on effective dose.nnnMATERIALS AND METHODSnFifty consecutive patients referred for exclusion of pulmonary embolism who had undergone a CTPA examination with conventional frontal topogram to plan scan length (protocol A) were compared with 50 consecutive patients who had undergone a CTPA study with frontal and additional lateral topogram for planning (protocol B) in a retrospective audit. Optimal scan length was defined from lung apex to lung base. Mean excess scan length beyond these landmarks was determined. The mean organ doses to the thyroid, liver, and stomach, as well as mean effective dose, were estimated using standard conversion factors.nnnRESULTSnThe mean excess scan length was significantly lower in protocol B compared to the protocol A cohort (19.5 ± 17.4 mm [mean ± standard deviation] versus 39.1 ± 20.4 mm, p < 0.0001). The mean excess scan length below the lung bases was significantly lower in the protocol B cohort compared to the protocol A group (7.5 ± 12.7 mm versus 23 ± 16.6 mm, p < 0.0001), as were the mean organ doses to the stomach (4.24 ± 0.81 mGy versus 5.22 ± 1.06 mGy, p < 0.0001) and liver (5.60 ± 0.64 mGy versus 6.38 ± 0.81 mGy, p < 0.0001). A non-significant reduction in over-scanning above the apices in protocol B was observed compared with protocol A (12 ± 8.8 mm versus 16.2 ± 13.6 mm, p = 0.07), which equated to lower mean thyroid organ dose in (3.28 ± 1.76 mGy versus 4.11 ± 3.11 mGy, p = 0.104).nnnCONCLUSIONnThe present audit indicates that incorporation of a lateral topogram into the CTPA protocol, together with radiographer education, reduces excess scan length, which significantly reduces the dose to the liver and stomach, and potentially lowers the dose to the thyroid. This simple dose-saving technique can be applied to all CT investigations of the chest on all CT systems with immediate effect.

A Novel Cause of Acute Coronary Syndrome Due to Dynamic Extrinsic Coronary Artery Compression by a Rib Exostosis: Multimodality Imaging Diagnosis

We report a case of acute coronary syndrome secondary to intermittent extrinsic compression of the left anterior descending coronary artery by inward-pointing rib exostosis in an 18-year-old woman during forceful repeated expiration in labour. The diagnosis was achieved using multimodality noninvasive cardiac imaging. In particular, we demonstrated the novel role of expiratory-phase cardiac computed tomography in confirming the anatomical relationship of the bony exostosis to the left anterior descending coronary artery. The case reminds us the heart and mediastinum move dynamically, relative to the bony thorax, throughout the respiratory cycle, and that changes in cardiac physiology in pregnancy may become pathological.