Improving practice in radiology: a quality-improvement project examining CT colonography patient dose and scanning technique

AIM

To audit scanning technique and patient doses for computed tomography (CT) colonography (CTC) examinations in a large UK region and to identify opportunities for quality improvement.

MATERIALS AND METHODS

Scanning technique and patient dose data were gathered for both contrast-enhanced and unenhanced CTC examinations from 33 imaging protocols across 27 scanners. Measurements of patient weight and effective diameter were also obtained. Imaging protocols were compared to identify technique differences between similar scanners. Scanner average doses were calculated and combined to generate regional diagnostic reference limits (DRLs) for both examinations.

RESULTS

The regional DRLs for contrast-enhanced examinations were volume CT dose index (CTDIvol) of 11 and 5 mGy for the two scan phases (contrast-enhanced and either delayed phase or non-contrast enhanced respectively), and dose-length product (DLP) of 740 mGy·cm. For unenhanced examinations, these were 5 mGy and 450 mGy·cm. These are notably lower than the national DRLs of 11 mGy and 950 mGy·cm. Substantial differences in scan technique and doses on similar scanners were identified as areas for quality-improvement action.

CONCLUSION

A regional CTC dose audit has demonstrated compliance with national DRLs but marked variation in practice between sites for the dose delivered to patients, notably when scanners of the same type were compared for the same indication. This study demonstrates that the national DRL is too high for current scanner technology and should be revised.

Tumour growth rate of carcinoma of the colon and rectum: retrospective cohort study

BACKGROUND

The growth pattern of colorectal cancer is seldom investigated. This cohort study aimed to explore tumour growth rate in colorectal cancers managed non-surgically or deemed not resectable, and to determine its implication for prognosis.

METHODS

Consecutive patients with colonic or rectal adenocarcinoma were identified through the colorectal multidisciplinary team database at Leeds Teaching Hospitals NHS Trust over a 2-year interval. Patients who received no treatment (surgery, stenting, colonic defunctioning procedures, chemotherapy, radiotherapy) and who underwent CT twice more than 5 weeks apart were included. Multidetector CT/three-dimensional image analysis was performed independently by three experienced radiologists.

RESULTS

Of 804 patients reviewed, 43 colorectal cancers were included in the final analysis. Median age at first CT was 80 (73-85) years and the median interval between scans was 150 (i.q.r. 72-471) days. An increase in T category was demonstrated in 31 of 43 tumours, with a median doubling time of 211 (112-404) days. The median percentage increase in tumour volume was 34·1 (13·3-53·9) per cent per 62 days. The all-cause 3-year mortality rate was 81 per cent (35 of 43) with a median survival time of 1·1 (0·4-2·2) years after the initial diagnostic scan. In those obstructed, the relative risk of death from subsequent perforation was 1·26 (95 per cent c.i. 1·07 to 1·49; P = 0·005).

CONCLUSION

This study documented a median doubling time of 211 days, with a concerning suggestion of tumour progression, which has implications for the current management standard.

Acceptability of a new practice development for radiographers focussed on reducing 'never events' related to nasogastric feeding tubes in adult patients

INTRODUCTION

Ascertain if a new practice development designed to reduce 'never events' from feeding through misplaced nasogastric tubes (NGT) in a large teaching hospital Trust was acceptable to a large radiography workforce.

METHODS

Despite National Patient Safety Agency guidance advising on safe practice for confirming position of NGTs a number of 'never events' still occur nationally due to misinterpretation of the check X-ray. A new practice development for radiographers included providing an immediate comment and removal of misplaced NGTs at the time of the check X-ray examination. Success of the new system was partly assessed using qualitative and quantitative measures of radiographer opinion of the training and different aspects of the system.

RESULTS

There was a significant improvement in radiographers' level of confidence in image interpretation after training (58/98 positive responses before, 89/98 positive after training) and after five months of experience at undertaking the role (96/98 positive) (p < 0.01). There was increased confidence in NGT removal post training and with five months of experience (16/95 positive before training, 67/96 positive after and 81/95 positive with five months of experience). 97/98 (99%) of radiographers agreed the new system benefits patients, 93/98 (95%) believed it a positive step for the radiography profession.

CONCLUSION

Evaluation of this new practice development has shown it was embraced by radiographers and is a workable and potentially cost-effective solution in addressing real time image interpretation issues that were evident from previous 'never events'. Large scale implementation of this system across the NHS Radiography workforce should be considered.

Characterization of Chlamydiaceae species using PCR and high resolution melt curve analysis of the 16S rRNA gene

AIM

To design a rapid diagnostic test to differentiate species belonging to the family Chlamydiaceae.

METHODS AND RESULTS

Five oligonucleotide sets each targeting various conserved regions of the genome of six species (Chlamydia muridarum, C. suis, C. trachomatis, Chlamydophila felis, Cp. pneumoniae and Cp. psittaci) belonging to the family Chlamydiaceae were tested for their suitability for polymerase chain reaction (PCR) and high resolution melt (HRM) curve analysis to differentiate Chlamydiaceae species. Three of the oligonucleotide sets were able to detect all six reference species used in this study, but only one set (16SG) could clearly differentiate between them by HRM curve analysis. The PCR-HRM curve analysis confidence percentages correlated strongly with the nucleotide sequence identities. Clinical specimens from a number of animal species suspected of chlamydiosis were tested with the newly developed 16SG PCR-HRM curve analysis and sequenced to confirm the infecting species. It was demonstrated that PCR-HRM using the 16SG oligonucleotide set could relate the infecting Chlamydiaceae species to the most similar (based on 16S rRNA gene nucleotide sequence) reference species tested. Although Cp. pecorum was not included initially as a reference species in this assay, inclusion of a field isolate of Cp. pecorum as a reference allowed two koala specimens to be correctly identified.

CONCLUSION

PCR-HRM analysis using the oligonucleotide set 16SG is a robust, simple and rapid technique for differentiation of at least the Chlamydiaceae species used in this study.

SIGNIFICANCE AND IMPACT OF THE STUDY

This technique allowed for the rapid detection and identification of the six Chlamydiaceae reference species and may be useful for identification of uncharacterized Chlamydiaceae species or for use in animal species where occurrence of the disease has not been fully investigated.

Prognostic significance of BRCA1 expression in sporadic breast carcinomas

BRCA1 is a tumour suppresser gene frequently mutated in familial breast cancer and thought to influence the progression of sporadic breast cancer. Decreased BRCA1 mRNA and protein expression has been identified in breast cancer cell lines and sporadic breast tumours. Here the prognostic significance of reduced BRCA1 protein expression is investigated in primary operable breast cancer. Immunohistochemical analysis was used to determine the level of BRCA1 protein expression in 100 breast cancers. BRCA1 expression was compared with known prognostic factors and survival to investigate its prognostic significance. BRCA1 nuclear expression was reduced by varying amounts in breast carcinomas. A progressive loss of BRCA1 expression correlated well with higher histological grade (p = 0.002) and an excess of medullary/atypical medullary/grade 3 ductal carcinomas (p = 0.0001). When adjusted for grade, patients with loss of BRCA1 expression had a significantly longer disease-free survival time. Loss of BRCA1 expression associated with high-grade breast tumours suggests that BRCA1 may play an important role in the pathogenesis of sporadic breast cancer.