Perfusion CT to assess angiogenesis in colon cancer: technical limitations and practical challenges

OBJECTIVE

Perfusion CT may have the potential to quantify the degree of angiogenesis of solid tumours in vivo. This study aims to identify the practical and technical challenges inherent to the technique, and evaluate its feasibility in colorectal tumours.

METHODS

51 patients from 2 institutions prospectively underwent a single perfusion CT on 2 different multidetector scanners. The patients were advised to breath-hold as long as possible, followed by shallow breathing, and were given intravenous buscopan to reduce movement. Numerous steps were explored to identify the challenges.

RESULTS

43 patients successfully completed the perfusion CT as per protocol. Inability to detect the tumour (n=3), misplacement of dynamic sequence co-ordinates (n=2), failure of contrast injection (n=2) and displacement of tumour (n=1) were the reasons for failure. In 14 cases excessive respiratory motion displaced the tumour out of the scanning field along the temporal sequence, leading to erroneous data capture. In nine patients, minor displacements of the tumour were corrected by repositioning the region of interest (ROI) to its original position after reviewing each dynamic sequence slice. In 20 patients the tumour was stable, and data captured from the ROI were representative, and could have been analysed by commercially available Body Tumor Perfusion 3.0® software (GE Healthcare, Waukesha, WI). Hence all data were manually analysed by MATLAB® processing software (MathWorks, Cambridge, UK).

CONCLUSION

Perfusion CT in tumours susceptible to motion during acquisition makes accurate data capture challenging and requires meticulous attention to detail. Motion correction software is essential if perfusion CT is to be used routinely in colorectal cancer.

Relevance of magnetic resonance imaging-detected pelvic sidewall lymph node involvement in rectal cancer

BACKGROUND

The significance of magnetic resonance imaging (MRI)-suspected pelvic sidewall (PSW) lymph node involvement in rectal cancer is uncertain.

METHODS

Magnetic resonance images were reviewed retrospectively by specialist gastrointestinal radiologists for the presence of suspicious PSW nodes. Scans and outcome data were from patients with biopsy-proven rectal cancer and a minimum of 5 years' follow-up in the Magnetic Resonance Imaging and Rectal Cancer European Equivalence Study. Overall disease-free survival (DFS) was analysed using the Kaplan-Meier product-limit method and stratified according to preoperative therapy. Binary logistic regression was used to match patients for propensity of clinical and staging characteristics, and further survival analysis was carried out to determine associations between suspicious PSW nodes on MRI and survival outcomes.

RESULTS

Of 325 patients, 38 (11·7 per cent) had MRI-identified suspicious PSW nodes on baseline scans. Such nodes were associated with poor outcomes. Five-year DFS was 42 and 70·7 per cent respectively for patients with, and without suspicious PSW nodes (P < 0·001). Among patients undergoing primary surgery, MRI-suspected PSW node involvement was associated with worse 5-year DFS (31 versus 76·3 per cent; P = 0·001), but the presence of suspicious nodes had no impact on survival among patients who received preoperative therapy. After propensity matching for clinical and tumour characteristics, the presence of suspicious PSW nodes on MRI was not an independent prognostic variable.

CONCLUSION

Patients with suspicious PSW nodes on MRI had significantly worse DFS that appeared improved with the use of preoperative therapy. These nodes were associated with adverse features of the primary tumour and were not an independent prognostic factor.

Optimising magnetic resonance imaging for preoperative staging and surgical planning in colon cancer at 1.5 tesla and 3.0 tesla

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Background: The aim of this study was to determine best technique for future preoperative staging and operative planning in colon cancer using MRI at 1.5T, and feasibility at 3.0T.

Methods: 39 scans were performed in 4 healthy volunteers comparing bowel distension using different oral contrast techniques; no oral preparation, 1L of water, 1L of poly ethylene glycol (Klean-Prep), and 1L of 2.1% barium sulphate and 3.2% sorbitol solution (E-Z-Cat) at 1.5T. Bowel distension was scored blindly by 2 experienced radiologists. A further 35 scans compared image quality of T2-weighted pulse sequences; 2D-TrueFISP, 3D-TrueFISP, HASTE, 2D-TSE and 3D-TSE. Scans were scored for movement artefact, colon wall and colon mesentery visualisation. Signal to noise ratio (SNR) was calculated. Inter-observer agreement was assessed using Cohen's Kappa. Equivalent optimised protocols were derived at 3.0T and tested for feasibility.

Results: Inter-observer agreement for scoring was good (kappa = 0.61-0.67). Sorbitol-barium sulphate gave significantly better small bowel distension than no oral preparation, water and Klean-Prep (mean score 3.8 vs 1.6, 2.2 and 1.9, p≤0.007). 2D TrueFISP sequences gave the highest mean score for scan quality, significantly better than 3D-TSE, 2D-TSE, 3D-TrueFISP and HASTE (mean 10.6 vs 3.2, 7.8, 7.7 and 7.4, p≤0.012). 2D-TSE sequences obtained best SNR, significantly greater than obtained using 3D-TSE (p=0.045). 3.0T sequences were comparable or superior.

Conclusions: Colon imaging using MRI requires fast sequences and adequate bowel distension. Our observations indicate that 2D-TrueFISP and 2D-TSE sequences with 1L Sorbitol-Barium sulphate orally give the best T2-weighted images of the colon wall and adjacent structures for cancer staging at 1.5T; equivalent 3.0T protocols are possible.

No significant financial relationships to disclose.

Silica wool filtration (SIFT) assay: a simple system to estimate the percentage of acrosome-reacted sperm

OBJECTIVE

To develop a simple assay using the silica wool filtration (SIFT) procedure to estimate percentage of acrosome-reacted (AR) sperm.

SETTING

Private andrology laboratory.

MATERIALS AND METHODS

Capacitated sperm processed by the SIFT procedure to remove nonviable sperm and those with broken membrane were acrosome reacted by induction with a calcium ionophore. Following the acrosome reaction, the sample was processed by the SIFT procedure. Sperm concentration and acrosomal status were also determined before and after the SIFT procedure.

RESULTS

The SIFT procedure prevented AR sperm from filtering (mean +/- SD, 22.2 +/- 1.9 vs. 9.8 +/- 4.9%). The mean percent of sperm retained in the filter (SIFT assay: 61.8 +/- 21.5%) was significantly higher than the percent of AR sperm estimated by a staining technique (26.4 +/- 7.3%), but they were significantly correlated (r = .34) with each other. The filtration of capacitated sperm prior to induction of the acrosome reaction eliminated, or at least minimized, the possibility of falsely increasing the percent of AR sperm estimated by the SIFT assay. The higher estimate obtained by SIFT assay, therefore, suggests that it may be estimating sperm at various stages that are undergoing the acrosome reaction.

CONCLUSION

The findings suggest that the SIFT assay could be used to estimate the percentage of AR spermatozoa.