k-space filtering in 2D gradient-echo breath-hold hyperpolarized 3He MRI: spatial resolution and signal-to-noise ratio considerations.

In this work some of the factors that can influence the signal-to-noise ratio (SNR) and spatial resolution in MR images of inhaled hyperpolarized gases are systematically addressed. In particular, the effects of RF depletion of longitudinal polarization and image gradient diffusion dephasing were assessed in terms of their contribution to a k-space filter. By means of theoretical simulations and a novel method of experimental validation using a variable transverse magnetization of the 1H signal, systematic quantitative and qualitative investigations of the effects of k-space filtering intrinsic to imaging of hyperpolarized gas were made. A 2D gradient-echo image is considered for a range of flip angles with centric, sequential, and half-Fourier Cartesian phase-encoding strategies, and the results are assessed in terms of SNR and spatial resolution in the reconstructed images. Centric phase encoding was found to give the best SNR at higher flip angles, with a trade-off in spatial resolution compared to sequential phase encoding. A half-Fourier approach potentially offers increased SNR through the use of higher flip angles without compromising the spatial resolution, which is comparable to that achieved with sequential encoding.     

Computed tomography perfusion imaging in acute stroke

The development of thrombolytic and neuroprotective agents for the treatment of acute stroke has created an imperative for improved imaging techniques in the assessment of acute stroke. Five cases are presented to illustrate the value of perfusion CT in the evaluation of suspected acute stroke. To obtain the perfusion data, a rapid series of images was acquired without table movement following a bolus of contrast medium. Cerebral blood flow, cerebral blood volume and mean transit time were determined by mathematically modelling the temporal changes in contrast enhancement in the brain and vascular system. Pixel-by-pixel analysis allowed generation of perfusion maps. In two cases, CT-perfusion imaging usefully excluded acute stroke, including one patient in whom a low-density area on conventional CT was subsequently proven to be tumour. Cerebral ischaemia was confirmed in three cases, one with an old and a new infarction, one with a large conventional CT abnormality but only a small perfusion defect, and one demonstrating infarct and penumbra. Perfusion CT offers the ability to positively identify patients with non-haemorrhagic stroke in the presence of a normal conventional CT, to select those cases where thrombolysis is appropriate, and to provide an indication for prognosis.     

Interleaved pulsed MAMBA: a new parallel slice imaging method.

A method of acquiring slices in parallel is described which uses interleaved sets of pulsed B(0) field coils to generate discrete regions of uniform field within the main magnetic field known as interleaved MAMBA (multiple acquisition micro B(0) array). Simulations of a number of coil designs were performed using the Biot-Savart law. A six-step coil was built and interfaced to a 0.17 T Niche MRI system and the field steps measured using an imaging technique. Measured field steps were in good agreement with the values predicted by simulation. The coil design was then scaled up by a factor of three, interfaced to a 1.5 T whole-body MRI system, and scans of the hands and arms of volunteers were acquired from up to four field steps using standard spin and gradient echo sequences. Images were also acquired simultaneously from two field steps with no frequency encode aliasing and one excitation. The one-dimensional interleaved pulsed MAMBA step field technique shows great promise for enabling many slices to be acquired simultaneously along the axis of the coil for rapid volumetric studies without the need for multiple shot Hadamard encoding. Extension of interleaved coil design to two or three dimensions is feasible, which could provide full spatial coverage combined with ultra-rapid data acquisition.     

A seroepidemiological study of cytomegalovirus and Epstein-Barr virus in rheumatoid arthritis and sicca syndrome.

Antibodies to cytomegalovirus (CMV) and Epstein-Barr virus capsid antigen (EBVCA) were examined in 41 patients with rheumatoid arthritis (RA), 26 patients with primary sicca syndrome, and 26 healthy subjects of similar age and sex. IgG antibody titres to EBVCA and CMV were similar in all three groups, apart from a trivial increase of antibodies to EBVCA in RA. False positive IgM anti-CMV antibodies detected in serum from one patient with sicca syndrome and 20 patients with RA were shown to be due to rheumatoid factors. These data did not support recent suggestions that patients with these diseases showed exaggerated immunological responses to either virus and emphasised the need to incorporate adequate laboratory and disease controls when seroepidemiological studies are performed on sera containing rheumatoid factors and autoantibodies.     

Association of MHC antigens with susceptibility to and severity of rheumatoid arthritis in multicase families.

A study of HLA association with rheumatoid arthritis (RA) in multicase families has been performed in north east England. Two hundred and nineteen individuals from 13 families were assessed for the presence of RA, and all were HLA typed. Thirty-nine were found to have classical or definite RA by American Rheumatism Association (ARA) criteria. Thirty-five (90%) of these possess HLA-DR4, confirming the previously reported association of RA with DR4. A further 19 individuals were found to have probable RA or gave a convincing history of previous inflammatory polyarthritis. Thirteen (68%) of these possess HLA-DR4, and this is not significantly different from non-affected family members of whom 63% possess DR4. These results suggest that HLA-DR4 is associated only with the more severe forms of RA. Homozygosity for HLA-DR4 was not associated with either earlier onset or more severe disease when compared with heterozygous DR4. Possession of the haplotype most commonly inherited with the RA in individual families was not associated with earlier onset but may be associated with more severe disease. The severity of RA appears to be influenced by the major histocompatibility complex (MHC) in these families.     

The use of biodegradable (SX-ELLA) oesophageal stents to treat dysphagia due to benign and malignant oesophageal disease

Background

Biodegradable (BD) oesophageal stents have been available commercially only since 2008 and previous published research is limited. Our aim was to review the use of BD stents to treat dysphagia in benign or malignant oesophageal strictures.

Methods

Patients were identified from a prospective interventional radiological database. BD stents were inserted radiologically under fluoroscopic control.

Results

Between July 2008 and February 2011, 25 attempts at placing SX-ELLA biodegradable oesophageal stents were made in 17 males and five females, with a median age of 69 (range = 54–80) years. Two patients required more than one BD stent. Indications were benign strictures (n = 7) and oesophageal cancer (n = 17). One attempt was unsuccessful for a technical success rate of 96% with no immediate complications. Clinical success rate was 76%. Median dysphagia score before stent insertion was 3 (range = 2–4) compared to 2 (range = 0–3) after stent insertion (p = 0.0001).

Conclusion

BD stents provide good dysphagia relief for the life time of the stent. They may help avoid the use of feeding tubes in patients having radical chemoradiotherapy or awaiting oesophagectomy. They do not require removal or interfere with radiotherapy planning via imaging. However, the reintervention rate is high after the stent dissolves.     

A Population-Based Cohort Study of Emergency Appendectomy Performed in England and New York State

Background

To compare selected outcomes (30-day reoperation and total length of hospital stay) following emergency appendectomy between populations from New York State and England.

Methods

This retrospective cohort study used demographic and in-hospital outcome data from Hospital Episode Statistics (HES) and the New York Statewide Planning and Research Cooperative System (SPARCS) administrative databases for all patients aged 18+ years undergoing appendectomy between April 2009 and March 2014. Univariate and adjusted multivariable logistic regression were used to test significant factors. A one-to-one propensity score matched dataset was created to compare odd ratios (OR) of reoperations between the two populations.

Results

A total of 188,418 patient records, 121,428 (64.4%) from England and 66,990 (35.6%) from NYS, were extracted. Appendectomy was completed laparoscopically in 77.7% of patients in New York State compared to 53.6% in England (P < 0.001). The median lengths of hospital stay for patients undergoing appendectomy were 3 (interquartile range, IQR 2–4) days versus 2 (IQR 1–3) days (P < 0.001) in England and New York State, respectively. All 30-day reoperation rates were higher in England compared to New York State (1.2 vs. 0.6%, P < 0.001), representing nearly a twofold higher risk of 30-day reoperation (OR 1.88, 95% CI 1.64–2.14, P < 0.001). As the proportion of appendectomy completed laparoscopically increased, there was a reduction in the reoperation rate in England (correlation coefficient ?0.170, P = 0.036).

Conclusions

Reoperations and total length of hospital stay is significantly higher following appendectomy in England compared to New York State. Increasing the numbers of appendectomy completed laparoscopically may decrease length of stay and reoperations.

     

Use of a screening questionnaire for post-traumatic stress disorder (PTSD) on a sample of UK ICU patients

Background: Although rates vary across studies, research in recent years shows that prevalence of post-traumatic stress disorder (PTSD) following intensive care unit (ICU) can be high. Presently no screening tool assessing all three PTSD symptom categories has been validated in ICU patients. The aim of the study was to conduct a preliminary validation of such a measure, the UK- Post-Traumatic Stress Syndrome 14-Questions Inventory (UK-PTSS-14).
Methods: A case series cohort study performed at two ICUs in two UK district general hospitals. The UK-PTSS-14 was administered at three time-points (4–14 days, 2 months and 3 months post-ICU discharge). At time-point three participants also completed the Post-traumatic Stress Diagnostic Scale (PDS) and the Impact of Events Scale (IES).
Results: Forty-four patients completed the 3-month follow up. The UK-PTSS-14 was internally reliable at all three time-points (Cronbach's α=0.89, 0.86 and 0.84, respectively). Test–retest reliability was highest between time-points two and three (ICC=0.90). Concurrent validity at time-point three was high against the PDS ( r =0.86) and the IES ( r =0.71). Predictive validity was highest at time-point two ( r =0.85 with the PDS and r =0.71 with the IES). Receiver operator characteristic curve analysis suggested the highest levels of sensitivity (86%) and specificity (97%) for diagnosis of PTSD were at time-point two, with an optimum decision threshold of 45 points.
Conclusion: This preliminary validation study suggests that the UK-PTSS-14 could be reliably used as a screening instrument at 2 months post-discharge from the ICU to identify those patients in need of referral to specialist psychological services.     

Fibrillin microfibrils are reduced in skin exhibiting striae distensae

Striae distensae (striae: stretch marks) are a common disfiguring condition associated with continuous and progressive stretching of the skin—as occurs during pregnancy. The pathogenesis of striae is unknown but probably relates to changes in those structures that provide skin with its tensile strength and elasticity. Such structures are components of the extracellular matrix, including fibrillin, elastin and collagens. Using a variety of histological techniques, we assessed the distribution of these extracellular matrix components in skin affected by striae. Pregnant women were assessed for the presence of striae, and punch biopsies were obtained from lesional striae and adjacent normal skin. Biopsies were processed for electron microscopy, light microscopy and immunohistochemistry. For histological examination, 7 μm frozen sections were stained so as to identify the elastic fibre network and glycosaminoglycans. Biopsies were also examined with a panel of polyclonal antibodies against collagens I and III, and fibrillin and elastin. Ultrastructural analysis revealed alterations in the appearance of skin affected by striae compared with that of normal skin in that the dermal matrix of striae was looser and more floccular. Light microscopy revealed an increase in glycosaminoglycan content in striae. Furthermore, the number of vertical fibrillin fibres subjacent to the dermal–epidermal junction (DEJ) and elastin fibres in the papillary dermis was significantly reduced in striae compared with normal skin. The orientation of elastin and fibrillin fibres in the deep dermis showed realignment in that the fibres ran parallel to the DEJ. However, no significant alterations were observed in any other extracellular matrix components. This study identifies a reorganization and diminution of the elastic fibre network of skin affected by striae. Continuous strain on the dermal extracellular matrix, as occurs during pregnancy, may remodel the elastic fibre network in susceptible individuals and manifest clinically as striae distensae.