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9 Contrast dose reduction in clinical CMR at 3T MRI: impact on LGE image quality
IntroductionLimited data exist on the optimum dose of contrast needed for tissue characterisation using CMR at 3T. We assessed whether reduced contrast dose could provide similar quality of late gadolinium enhanced (LGE) images in standard clinical CMR.Materials and MethodsThis analysis included patients undergoing clinical CMR scans at Glenfield hospital, Leicester for various indications between November 2022-June 2023. All participants had LGE imaging performed as per clinical practice (either segmented, single-shot or free-breathing motion-corrected) using a 3T scanner (either Siemens Skyra or Vida). Patients underwent CMR scans with a lower dose of contrast (Clariscan, GE HealthCare) at 0.1mmol/kg and were compared with patients receiving the standard dose of 0.15mmol/kg in the previous three months. Scan quality and LGE images were evaluated retrospectively with blinding to dose of contrast given using a grading of non-diagnostic, diagnostic, good or optimum. LGE-to-blood pool ratio was calculated for all participants who had LGE present. Cost-benefit analysis was assessed using standard contrast tariffs and number of vials used per patient.Results101 participants with standard-dose and 100 participants with low-dose were compared. There was no significant difference in the type of LGE sequence used in the two groups. There was no significant difference in overall scan quality in the standard dose group (non-diagnostic 6%, diagnostic 20%, good 47%, optimum 28%) compared to low dose (non-diagnostic 3%, diagnostic 18%, good 44% and optimum 34%). Likewise, there was no difference in the LGE image quality in the standard dose group (non-diagnostic 3%, diagnostic 17%, good 42%, optimum 39%) compared to low dose (non-diagnostic 2%, diagnostic 7%, good 41%, optimum 50%). Proportion of patients with LGE present was similar between the two groups (Standard 44% vs. Low dose 39%). LGE-to-blood pool ratio was higher in the low-dose compared to the standard-dose group (1.12 [0.71–1.30] vs. 0.76 [0.55–1.05]; P=0.010). Amongst the low-dose group, there was a cost-saving of 29%.DiscussionConclusionThe use of standard-dose contrast is not superior to using lower dose contrast when assessing LGE images. Low-dose contrast provides higher LGE-blood pool ratio and is associated with reduced service costs.Acknowledgements
Journal Article
22 An accelerometery-based evaluation of sitting time in cardiovascular prevention and rehabilitation participants
BackgroundSedentary behaviour (i.e., sitting time) is a modifiable risk factor for cardiovascular disease and an important part of secondary prevention. Sedentary behaviour greater than 9.5 hours per day is strongly associated with all-cause mortality. Few studies have quantified sitting time in cardiovascular prevention and rehabilitation (CPR).AimsThe primary aim was to robustly evaluate sitting and physical activity time in CPR attendees.Methods105 consecutive patients attending a CPR programme in Northern Ireland wore a blinded research-grade accelerometer (activPAL) on their thigh 24h/day for seven days as part of their initial assessment (IA). They then completed an individualised 8-12 week virtually-delivered CPR programme, which included personalised physical activity programming supported by a Fitbit device with weekly reviews and educational resources. At the end of programme (EOP) participants repeated the seven-day activPAL measurement. Sitting time was calculated as mean hours ± standard deviation (SD) and as a percentage of activPAL wear time during waking hours (WWT). A paired t-test compared differences in time spent sitting, standing and moderate-to-vigorous physical activity (MVPA) between IA to EOP.Results101 participants (96%) had valid activPAL data at both timepoints. Mean age was 62 years (±11 years). The majority were male (77%). The activPAL data demonstrated significant reductions in sitting time, increased standing time and increased MVPA (table 1). However upon programme completion, participants still spent 62% of their WWT sitting (mean ± SD: 9.73 hours ± 2.55).Abstract 22 Table 1Change in Sitting Time and Moderate-to-Vigorous Physical Activity ActivPAL output variables Pre Mean ±SD Post Mean ±SD Mean difference [95% CI ] P value Average total sitting time (hours/day) 10.53 ± 2.239.73 ± 2.55-0.80 [-1.30, -0.30] 0.002 Average total standing time (hours/day) 3.30 ± 1.854.03 ± 1.90 0.73 [0.43, 1.03] <0.001 Average MVPA time [step cadence >100/min] (hours/day) 0.49 ± 0.520.62 ± 0.58 0.13 [0.01, 0.25] 0.03 Total sitting time (% wear time) 68.7 ± 13.961.7 ± 15.6-7.5 [-10.5, -4.6] <0.001 ConclusionsWhilst the CPR programme resulted in reduced sitting time, daily sitting remained detrimentally high in CPR graduates. Despite participants meeting the MVPA recommendations within physical activity guidelines, sitting time remains a major concern. Routine assessment of sitting time in CPR is recommended. Effective interventions to reduce sitting in CPR warrants further investigation.
Journal Article
Cogwheel Rigidity in Subacute Combined Degeneration Unresponsive to Vitamin B12 Therapy
IntroductionParkinsonian symptoms seen with B12 deficiency have been described in five cases where B12 therapy has led to their elimination. Subacute combined degeneration (SCD) presenting with parkinsonian signs of cogwheel rigidity, unresponsive to B12 supplementation, has not heretofore been described.MethodsCase Study: This 62-year-old right-handed woman with a past medical history of hypothyroidism presented with complaints of trouble with memory. Cogwheel rigidity and pernicious anemia with low intrinsic factor and B12 levels (165 pg/ml) were found. SCD was diagnosed and treated with monthly B12 injections over the past three years, providing symptomatic relief, yet the cogwheeling persisted. She described never developing trouble with gait, movement disorders, autonomic abnormalities, olfactory dysfunction, disorders of sleep, visual hallucinations, or other parkinsonian symptoms.ResultsAbnormalities in Neurologic Examination: Cranial Nerve (CN) Examination: CN I: Alcohol Sniff Test: 9 (hyposmia). CN III, IV, VI: Bilateral ptosis. Motor Examination: 1+ Cogwheel rigidity both upper extremities. Drift Testing: Right pronator drift with left abductor digiti minimi sign. Reflexes: 3+ throughout other than 4+ ankle jerks. Quadriceps femoris bilaterally pendular. Bilateral Hoffman and Babinski reflexes present. B12 Level: 394 pg/ml (normal).DiscussionWhile predominantly affecting the posterior columns and the lateral corticospinal tract, the demyelination may further extend into adjacent fibers including the reticulospinal tract and the rubrospinal tract, the tracts which, in Parkinson’s Disease, have been cited for their role in maintenance of tone and thus cogwheeling. Additionally, low B12 and elevated homocysteine levels have been noted as potential contributory factors in the pathogenesis of Parkinson’s Disease. It is also possible that this is a violation of Occam’s razor, that this individual has two separate distinct diseases — the prominent subacute combined degeneration as well as a subclinical parkinsonism which was revealed on neurologic examination. The parkinsonian signs may have been present prior to the B12 deficiency, and if not for the examination findings, could have remained undiscovered for decades. In those that present with Subacute Combined Degeneration, evaluation for parkinsonism is warranted.FundingNo Funding
Journal Article