The emerging role of cardiac computed tomography for the assessment of coronary perfusion: a systematic review and meta-analysis

Background

Computed tomography perfusion (CTP) is an emerging method which, coupled with the anatomical detail afforded by cardiac computed tomographic angiography (CCTA), may allow for determination of both structural and physiologic significance of coronary stenoses with a single imaging modality. This study was designed to execute a systematic review/meta-analysis to determine the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CTP as compared with reference standards for detection of significant coronary artery stenoses and impaired perfusion.

Methods

A systematic review identified 13 out of 4368 studies allowing a calculation of sensitivity, specificity, PPV, and NPV on a per patient or per vessel or per segment basis using radionuclide myocardial perfusion imaging (MPI), conventional coronary angiography (CCA), magnetic resonance perfusion imaging (MRPI), or fractional flow reserve (FFR) as the reference standard. Meta-analyses of results were carried out using random effects modelling.

Results

Most studies used a maximal vasodilator stress protocol with adenosine, provided information mainly on a per vessel basis, and used myocardial perfusion imaging or CCA as the reference standard. Of the studies comparing combinations of both anatomical and functional imaging, the most rigourous standard was CCA/FFR. Compared with the latter, CCTA/CTP had sensitivity, specificity, PPV, and NPV of 81%, 93%, 87%, and 88%, respectively.

Conclusions

CTP shows promise as an adjunct to CCTA, potentially allowing determination of both structural and physiologic significance with a single imaging modality.     

Percutaneous closure of an aortic prosthetic paravalvar leak: an Australian first

Percutaneous intervention is becoming an increasingly recognised modality for the management of prosthetic paravalvar leaks (PVLs) with particular utility in severely symptomatic non-surgical candidates. To date, application of this intervention has predominantly involved closure of mitral valve PVLs. Consequently, current literature on its application to aortic PVLs is limited. This article describes what we believe to be the first percutaneous closure of an aortic prosthetic PVL in Australia.     

Nephrectomy for the failed renal allograft in children: predictors and outcomes

Background

There are no guidelines for the removal of a failed renal allograft, and its impact on subsequent dialysis and retransplantation has not yet been described.

Methods

We performed a 10-year review of allograft failure to study the factors that determined an outcome of transplant nephrectomy and choice of subsequent renal replacement therapy in children with or without nephrectomy.

Results

A total of 34 children developed graft failure over the 10-year study period, of whom 18 (53 %) required transplant nephrectomy. The median graft survival was 1.1 (range 0.2–10.6) versus 7.5 (1.5–15.0) years in the nephrectomy and non-nephrectomy groups, respectively (p?=?0.011). Children with graft failure within 1 year of transplantation were four-fold more likely to require transplant nephrectomy than those with graft failure after 1 year (p?=?0.04). Renal biopsy performed at ≤8 weeks prior to graft loss showed Banff grade II acute rejection in 13 of the 18 children who required subsequent nephrectomy versus three of the 13 children who did not need nephrectomy (p?=?0.01). Inflammation (fever, graft tenderness and raised C-reactive protein (CRP) in the 2 weeks preceding graft failure) was seen in 66 % of nephrectomized children, but not in any in the non-nephrectomy group (p?=?0.0003 for CRP between groups). Banff II rejection, an inflammatory response and the time post-transplantation significantly and independently predicted the outcome of nephrectomy (p?=?0.008, R ²?=?67 %). Human leukocyte antigen (HLA) antibody levels after graft failure were higher in the nephrectomy group (p?=?0.0003), but there was no difference between groups in terms of the presence or class of donor-specific antibodies. Of the children with graft failure, 82 % required dialysis (61 % hemodialysis) and 35 % have to date been successfully retransplanted.

Conclusions

Children with Banff II rejection, an inflammatory response and early graft loss are more likely to require transplant nephrectomy. Nephrectomy may be associated with higher circulating HLA antibody levels.     

Autonomic dysfunction in adult-onset alexander disease

Background

Alexander disease (AxD) is an astrogliopathy, resulting from a mutation in the glial fibrillary astrocytic protein gene. Different clinical subtypes have been described, including infantile, juvenile, and adult onset, based upon the age at which symptoms begin. Patients with the adult-onset form, develop a progressive, spastic paraparesis, palatal myoclonus, ataxia, and bulbar weakness. Autonomic nervous system (ANS) dysfunction has been reported as a potential manifestation of adult-onset AxD, but has not been well characterized.

Objective

We report a case of adult-onset AxD with symptomatic orthostatic hypotension (OH) and heat intolerance that underwent formal autonomic testing. In addition, a comprehensive literature search was conducted to review the frequency and pattern of autonomic dysfunction in this patient population.

Results

A 51-year-old patient was diagnosed with AxD at the age of 47, following an 8-year history of vertigo, intermittent diplopia, and sleep disturbance. The patient developed symptoms of OH, erectile dysfunction, and heat intolerance soon after his diagnosis. Autonomic testing demonstrated OH on tilt-table testing (47 mmHg decrease in BP with 18 BPM heart rate increment) with absent late phase II and IV responses during the Valsalva maneuver, severe cardiovagal impairment, and preserved postganglionic sympathetic sudomotor function. These findings were interpreted as being consistent with central autonomic failure. The most common autonomic symptoms reported in other AxD cases include constipation, urinary incontinence, and sphincter dysfunction. To our knowledge, this is the first report of formal autonomic testing in AxD.

Conclusion

Signs and symptoms of ANS impairment can occur in patients with AxD, and can include orthostatic hypotension and bowel/bladder dysfunction. Autonomic testing in our patient suggests impairment in central autonomic pathways.     

Certification in Medical Physics Imaging,The Workforce and Training Models

The pathway to becoming a qualified medical physicist (QMP) in the imaging physics disciplines includes several certification organizations. Imaging QMPs play an essential role in the safe practice of the diagnostic disciplines, and their qualifications are necessary for compliance with federal bodies and professional accreditation organizations. The future demand for imaging QMPs is largely unknown, but professional organizations that represent these groups agree that efforts should be made to increase the number of matriculating trainees. The number of imaging residency programs that provide the necessary professional experience to enter the certification pathway has increased substantially in recent years. Most of these programs follow a traditional academic hospital-based training model, but guidance on program construction from the accrediting body permits flexibility. Existing training models for medical physics imaging also include consortiums of affiliate partners and private consulting service groups. In this article, the authors briefly review the certification pathways for imaging QMPs, workforce estimates, and training models.     

Organ and effective doses in infants undergoing upper gastrointestinal (UGI) fluoroscopic examination

To provide more detailed data on organ and effective doses in digital upper gastrointestinal (UGI) fluoroscopy studies of newborns and infants, the present study was conducted employing the time-sequence videotape-analysis technique used in a companion study of newborn and infant voiding cystourethrograms (VCUG). This technique was originally pioneered [O. H. Suleiman, J. Anderson, B. Jones, G. U. Rao, and M. Rosenstein, Radiology 178, 653-658 (1991)] for adult UGI examinations. Individual video frames were analyzed to include combinations of field size, field center, x-ray projection, image intensifier, and magnification mode. Additionally, the peak tube potential and the mA or mAs values for each segment/subsegment or digital photospot were recorded for both the fluoroscopic and radiographic modes of operation. The data from videotape analysis were then used in conjunction with a patient-scalable newborn tomographic computational phantom to report both organ and effective dose values via Monte Carlo radiation transport. The study includes dose estimates for five simulated UGI examinations representative of patients ranging from three to six months of age. Effective dose values for UGI examinations ranged from 1.17 to 6.47 mSv, with a mean of 3.14 mSv and a large standard deviation of 2.15 mSv. The colon, lungs, stomach, liver, and esophagus absorbed doses in sum were found to constitute between 63 and 75% of the effective dose in these UGI studies. Representing 23-30% of the effective dose, the lungs were found to be the most significant organ in the effective dose calculation. Approximately 80-95% of the effective dose is contributed by the dynamic fluoroscopy segments with larger percentages found in longer studies. The mean effective dose for newborn UGI examinations was not found to be statistically different from that seen in newborn VCUG examinations.     

Health Halo Effects from Product Titles and Nutrient Content Claims in the Context of “Protein” Bars

Research on front-of-package (FOP) labeling demonstrates that nutrient content claims (e.g., “low fat”) can lead consumers to perceive foods as healthier in general—effects that have been interpreted using halo effect theories of impression formation. Extending this work, the present study investigates whether these effects may depend on whether nutrient information comes in the form of a nutrient content claim (“good source of protein”) or embedded within the product title itself (“protein” bar)—an important question given the popularity of energy/nutrition bars and ongoing policy debates over food-labeling regulation. Results from a between-subjects experiment (n = 274) revealed that although both conditions increased perceived protein content for a nutritional bar, only the product title condition increased overall perceptions of product healthfulness—an effect mediated by increased perceptions of additional non-claimed “healthy” nutrients (fiber, iron). Finally, although the presence of a traffic light warning label increased perceived sugar and calorie content, it did not counteract the effect of the product title on perceived healthfulness. We conclude with a discussion focused on implications for policy and health halo effects in the context of food labeling.