The Cinderellas of the scanner: Magnetic resonance imaging 'pre-scan' and 'post-scan' times: Their determinants and impact on patient throughput

Background

Increasing demand for magnetic resonance imaging (MRI) has contributed to extended patient waiting times worldwide. This is particularly true in resource-limited environments, prompting this institutional workflow analysis.

Objective

To determine the ‘pre-’ and ‘post-scan’ times for normal-hour MRI studies conducted at a tertiary-level, public-sector South African hospital and to assess any association with demographic details, patient characteristics, anatomical site and scan parameters. A secondary objective was determination of the average daily MR ‘down’ time.

Methods

A prospective descriptive study stratifying MRI workflow into ‘pre-scan’, ‘scan’, ‘post-scan’ and ‘down’ times. During ‘pre-‘ and ‘post-scan’ times patients occupied the scanner whilst staff performed tasks indirectly contributing to image acquisition. During ‘down’ time no patient occupied the MRI room. ‘Pre-’ and ‘post-scan’ times were compared with demographic details, patient characteristics, anatomical site and study parameters, utilising correlation analysis or analysis of variance (ANOVA).

Results

A total of 223 patients (n = 223) underwent 286 investigations in the 23-day review period. Seventy per cent of routine working time was utilised in image acquisition. The ‘pre-’ and ‘post-scan’ times together accounted for 19% and ‘down’ time for 11% of working time. Prolonged ‘pre-’ and ‘post-scan’ times were independently associated with age less than 12 years, anaesthesia, sedation and immobility (p < 0.01 in all cases). The longest median combined ‘pre-’ and ‘post-scan’ time by anatomical site (cholangiopancreatography, 21:46 min) was more than six times the shortest (pituitary fossa, 3:11 min).

Conclusion

A critical analysis of magnetic resonance ‘pre-’ and ‘post-scan’ times can provide valuable insights into opportunities for enhanced service efficiency.

An imaging workflow for characterizing phenotypical change in large histological mouse model datasets

MOTIVATION

This paper presents a workflow designed to quantitatively characterize the 3D structural attributes of macroscopic tissue specimens acquired at a micron level resolution using light microscopy. The specific application is a study of the morphological change in a mouse placenta induced by knocking out the retinoblastoma gene.

RESULT

This workflow includes four major components: (i) serial section image acquisition, (ii) image preprocessing, (iii) image analysis involving 2D pair-wise registration, 2D segmentation and 3D reconstruction, and (iv) visualization and quantification of phenotyping parameters. Several new algorithms have been developed within each workflow component. The results confirm the hypotheses that (i) the volume of labyrinth tissue decreases in mutant mice with the retinoblastoma (Rb) gene knockout and (ii) there is more interdigitation at the surface between the labyrinth and spongiotrophoblast tissues in mutant placenta. Additional confidence stem from agreement in the 3D visualization and the quantitative results generated.

AVAILABILITY

The source code is available upon request.