A method of dissecting the pelvic floor to allow anatomical validation of images of the soft tissues.

A method of intact postmortem removal of the pelvic floor for imaging correlation studies, with minimal access disfigurement, is described. This consists of subcutaneous removal of both ischiopubic rami with division of the obturator membrane cranial to the origin of the levator ani muscles. The anatomical relationships of soft tissue surrounding the distal birth canal are thus preserved. The report discusses the need for, constraints on, and limitations of such studies in the unique problems of determining the dynamic anatomical configuration of the soft tissues of the pelvic floor. It illustrates the clinical relevance of initial studies, and reviews the background contributions of members of the group.

Quantitative colorectal cancer perfusion measurement by multidetector-row CT: does greater tumour coverage improve measurement reproducibility?

The purpose of this study was to determine if greater z-axis tumour coverage improves the reproducibility of quantitative colorectal cancer perfusion measurements using CT. A 65 s perfusion study was acquired following intravenous contrast administration in 10 patients with proven colorectal cancer using a four-detector row scanner. This was repeated within 48 h using identical technical parameters to allow reproducibility assessment. Quantitative tumour blood volume, blood flow, mean transit time and permeability measurements were determined using commercially available software (Perfusion 3.0; GE Healthcare, Waukesha, WI) for data obtained from a 5 mm z-axis tumour coverage, and from a 20 mm z-axis tumour coverage. Measurement reproducibility was assessed using Bland-Altman statistics, for a 5 mm z-axis tumour coverage, and 20 mm z-axis tumour coverage, respectively. The mean difference (95% limits of agreement) for blood volume, blood flow, mean transit time and permeability were 0.04 (-2.50 to +2.43) ml/100 g tissue; +8.80 (-50.5 to +68.0) ml/100 g tissue/min; -0.99 (-8.19 to +6.20) seconds; and +1.20 (-5.42 to +7.83) ml/100 g tissue/min, respectively, for a 5 mm coverage, and -0.04 (-2.61 to +2.53) ml/100 g tissue; +7.40 (-50.3 to +65.0) ml/100 g tissue/min; -2.46 (-12.61 to +7.69) seconds; and -0.23 (-8.31 to +7.85) ml/100 g tissue/min, respectively, for a 20 mm coverage, indicating similar levels of agreement. In conclusion, increasing z-axis coverage does not improve reproducibility of quantitative colorectal cancer perfusion measurements.

Comparison of radiologists' confidence in excluding significant colorectal neoplasia with multidetector-row CT colonography compared with double contrast barium enema.

The aim of this study was to compare the confidence of experienced radiologists in excluding colonic neoplasia with CT colonography (CTC) compared with barium enema. 78 patients (median age 70 years, range 61-87 years, 44 women) underwent same day CTC and barium enema. Two radiologists experienced in reporting barium enema assessed whether the examination had excluded a polyp 6 mm or greater as "yes", "probably" or "no" for each of 6 colonic segments. Two different radiologists experienced in CTC independently performed the same assessment on the CT datasets. Responses were compared using a paired exact test. Formal barium enema and CT reports were compared with any endoscopic examination performed within 1 year. Studies reporting polyps 6 mm+ in patients not subsequently undergoing endoscopy were reviewed by two independent observers. Radiologists stated they had confidently excluded a significant lesion in 314 (71%) and 382 (86%) of 444 segments with barium enema and CTC, respectively (p<0.001). Confidence was significantly higher with CTC in the in the descending and ascending colon (p = 0.02 and p<0.001, respectively), and caecum (p<0.001). 22 patients underwent some form of endoscopy. Of five patients with proven colorectal neoplasia (including two with cancer), CTC and barium enema correctly identified five and three, respectively. In 56 patients not undergoing endoscopy, CTC reported 17 polyps 6 mm+, of which 16 were retrospectively classified as definite or probable. 11 could not be identified on the barium enema, even in retrospect. Confidence in excluding polyps 6 mm or larger is significantly greater with CT colonography particularly in the proximal colon.

Intra-individual comparison of patient acceptability of multidetector-row CT colonography and double-contrast barium enema.

AIMS: To compare the subjective acceptability of CT colonography in comparison with barium enema in older symptomatic patients, and to ascertain preferences for future colonic investigation. MATERIALS AND METHODS: The study population comprised 78 persons aged 60 years or over with symptoms suggestive of colorectal neoplasia, who underwent CT colonography followed the same day by barium enema. A 25-point questionnaire was administered after each procedure and an additional follow-up questionnaire a week later. Responses were compared using Wilcoxon matched pairs testing, Mann-Whitney test statistics and binomial exact testing. RESULTS: Participants suffered less physical discomfort during CT colonography (p = 0.03) and overall satisfaction was greater compared with barium enema (p = 0.03). On follow-up, respondents reported significantly better tolerance of CT colonography (p = 0.002), and were less prepared to undergo barium enema again (p < 0.001). Of 52 subjects expressing an opinion, all preferred CT to barium enema. CONCLUSION: Patient satisfaction was higher with CT colonography than barium enema. CT colonography caused significantly less physical discomfort and was overwhelmingly preferred by patients.

Multidetector-row CT duodenography in familial adenomatous polyposis: a pilot study.

AIM: To investigate the feasibility of using multidetector-row computed tomography (CT) duodenography to stage duodenal polyposis in patients with familial adenomatous polyposis. MATERIALS AND METHODS: Six patients underwent multidetector-row CT duodenography before upper gastrointestinal endoscopy. A single-blinded radiologist used a surface shaded three-dimensional endoluminal fly though and two-dimensional axial and multiplanar reformats to assign a score for maximum polyp size and number based on the Spigelman classification. Comparison was made with the corresponding Spigelman scores obtained from subsequent endoscopy. RESULTS: CT duodenography was technically successful in five of six patients. The CT derived Spigelman score based on maximum polyp size was accurate in all five patients. The CT derived Spigelman score based on polyp number was accurate in only two cases: Polyp number was overestimated in one patient and underestimated in a further two. In retrospect, fine carpeting of tiny duodenal polyps was poorly visualized with CT. CONCLUSIONS: CT duodenography is technically feasible and accurately predicts maximum polyp size but CT estimates of polyp number are relatively inaccurate. CT duodenography potentially has a useful role for duodenal surveillance in those patients intolerant of conventional endoscopy.

Local radiological staging of rectal cancer.

Rectal cancer is a common malignancy with a highly variable outcome. Local recurrence is dependent upon tumour stage and surgical technique. The role of pre-operative imaging is to determine which patients may be safely managed by surgery alone and which need additional therapy in order to facilitate surgery and improve outcome. This decision depends on the distinction between those with early and advanced disease. While trans-rectal ultrasound has traditionally been used to answer this question, a role for magnetic resonance imaging (MRI) is increasingly argued. This review will focus on the treatment options for rectal cancer and the clinical questions that subsequently arise for the radiologist to answer.

CT colonography practice in the UK: a national survey.

AIM: To determine the provision of computed tomography (CT) colonography in UK radiology departments. MATERIALS AND METHODS: A questionnaire relating to the availability of CT colonography, barriers to implementation, clinical indications, technique, and practitioners was posted to clinical directors of UK radiology departments. RESULTS: One hundred and thirty-eight departments responded. Fifty (36%) offered CT colonography in day-to-day clinical practice. Of those that did not, 68 of 87 (64%) cited limited scanner capacity as the main barrier. Of the 50 departments offering a service, 39 (78%) offered CT after incomplete colonoscopy, 36 (72%), after failed barium enema, and 37 (74%) as an alternative to barium enema. Of those offering a service, the number of studies performed varied between one per month (38%) to more than one per day (8%). Total experience varied between 20 or fewer studies (28%) to more than 300 (12%). Full bowel preparation was common (92%), as was dual positioning (90%). Colonography was interpreted by radiologists with a subspecialty interest in gastrointestinal imaging in 64% of centres offering a service. CONCLUSION: CT colonography is widely available in the UK, with approximately one-third of responders offering a service. Experience and throughput varies considerably. Limited CT scanner capacity is the major barrier to further dissemination.

Use of multidetector-row CT colonography for detection of colorectal neoplasia in patients referred via the Department of Health "2-Week-wait" initiative.

AIM: Patients referred under the Department of Health 2-week wait initiative with symptoms of colorectal cancer frequently undergo whole-colon examination. We investigated the use of computed tomography (CT) colonography as an alternative to colonoscopy in this scenario. MATERIALS AND METHODS: Fifty-four consecutive patients, referred via the 2-week wait initiative and scheduled for colonoscopy, consented to undergo multidetector CT colonography immediately before endoscopy. The site and morphology of any polyp or cancer detected by CT was noted and comparison made with subsequent colonoscopy. RESULTS: Colonoscopy detected polyps or cancer in 29 patients (53.7%). CT colonography prospectively detected 18 of 41 (44%) polyps of 1-5 mm, three of four (75%) polyps of 6-9 mm, four of four (100%) polyps 10 mm or larger, and five of six (83%) cancers. The missed cancer occurred early in the series and was a perceptive error. The overall sensitivity, specificity, positive predictive value and negative predictive value of CT colonography for cancer and polyps 10 mm or greater on a per patient basis were 90, 100, 100 and 98%, respectively. CT detected one renal cancer and one colonic cancer, initially missed due to incomplete colonoscopy. CONCLUSION: CT colonography is a robust technique for investigation of symptomatic patients. The learning curve must be overcome for optimal performance.

Potential clinical implications of direction of a trans-sphincteric anal fistula track.

BACKGROUND: The longitudinal direction of a trans-sphincteric anal fistula track through the anal sphincter complex may have implications regarding fistulotomy. METHODS: The angle of the track of trans-sphincteric fistulas relative to the longitudinal axis of the anal canal was measured before operation by means of magnetic resonance imaging (MRI) in 46 patients. This was compared with the findings at operation. RESULTS: The track passed cranially as well as laterally at an acute angle (less than 90 degrees ) in 23 patients while it passed either transversely or caudally at an obtuse angle (90 degrees or more) in the remaining 23. The internal opening was significantly higher in relation to the dentate line (above in eight patients, at the dentate line in 14 and below in one patient) when the track was acute than when it was obtuse (above in one, at the dentate line in 17 and below in five patients) (P = 0.004). The fistula track crossed the sphincter at a median angle of 35 degrees, 95 degrees and 132 degrees from internal openings sited above, at and below dentate line level respectively (P = 0.002). CONCLUSION: Fistula tracks passed cranially and laterally through the sphincter complex in half of these patients, and were most acutely angled on MRI when internal openings were situated above the dentate line. Preoperative MRI might alert surgeons to the potential hazard of fistulotomy being more extensive than anticipated from simple palpation of the level of the internal opening.

Optimizing bowel preparation for multidetector row CT colonography: effect of Citramag and Picolax.

AIM: To compare the adequacy and acceptability of Picolax and Citramag bowel cleansing agents for CT colonography. MATERIALS AND METHODS: Multidetector row CT colonography was performed in 124 subjects; 43 had been prepared with Picolax and 81 with Citramag. Datasets were assessed for retained fluid and solid residue, and overall adequacy of segmental visualization. Preparation acceptability was also assessed. RESULTS: There was significantly less retained fluid with Picolax. The odds of being in the next higher category for retained fluid when using Picolax were 0.33 (CI: 0.22-0.50, p<0.0001) when compared with Citramag, for all segments combined. However there was significantly more retained solid residue with Picolax. The odds of being in the next higher category for retained residue when using Picolax were 2.44 (CI: 1.41-4.24, p=0.002) when compared with Citramag, for all segments combined. There was no significant difference with respect to overall segmental visualization: the odds of a segment being adequately visualized when using Picolax were 1.52 (CI: 0.88-2.65, p=0.14) when compared with Citramag. There was no significant difference with respect to acceptability. CONCLUSION: Picolax results in a significantly drier colon than Citramag and associated with more retained residue. We found Picolax the more suitable preparation for CT colonography.

Magnetic resonance imaging for primary fistula in ano.

BACKGROUND: This was a prospective study designed to determine the therapeutic impact of magnetic resonance imaging (MRI) in primary fistula in ano, and to assess its effect on outcome. METHODS: Thirty patients with suspected primary fistula in ano underwent preoperative MRI, and the findings were revealed during surgery following examination under anaesthesia (EUA). Any effect on operative approach was noted. Outcome was assessed at a median of 12 months. RESULTS: Two patients had sinuses, one had no sepsis and 27 had fistulas: five superficial, seven intersphincteric, 14 trans-sphincteric and one suprasphincteric. MRI and EUA agreed in 15 patients and MRI findings altered the surgical approach in a further three (10 per cent); two of the latter patients were believed to have a sinus at EUA, which MRI correctly identified as a fistula, allowing definitive treatment. The therapeutic impact of MRI was therefore 10 per cent. Persisting disagreement between MRI and EUA in 12 patients mostly related to minor discrepancies in classification. Only one patient required further unplanned surgery, which was for skin-bridging rather than any new sepsis. CONCLUSION: In experienced hands, MRI has a therapeutic impact of 10 per cent for primary fistula in ano, precipitating surgery that is likely to reduce recurrence in a small, but important, proportion of patients.

Transvaginal power Doppler ultrasound in pelvic congestion.

PURPOSE: Pelvic congestion is diagnosed by transuterine venography, an invasive procedure requiring sedation and irradiation. Ultrasound may be an alternative but is hindered by slow flow within pelvic veins. In an attempt to counter this, we investigated the possible role of transvaginal power Doppler ultrasound. MATERIAL AND METHODS: 42 women with a clinical suspicion of pelvic congestion underwent transvaginal ultrasound. Adnexal veins were examined and a congestion score established. Planimetric measurements of adnexal vessels were obtained using power Doppler ultrasound, and uterine and ovarian morphology noted. All women then underwent transuterine venography and agreement with the ultrasound congestion score and morphologic features was determined. RESULTS: There was a trend towards weak positive correlation between ultrasound and venography congestion scores (r = 0.29, p = 0.06). However, agreement between scores was poor on an individual basis (95% limits of agreement, -3.9 to +2.7). Planimetric power Doppler assessments of adnexal vascularity were unrelated to venographic congestion. Instead, there was correlation between the number and diameter of ovarian follicles and venographic congestion: women with congestion tended to have significantly more (0.04) and smaller follicles (p = 0.001). CONCLUSION: There was poor individual agreement between ultrasound and venographic estimates of congestion. However, there was a direct relationship between venographic congestion score and ovarian morphology.

CT colonography: methods, pathology and pitfalls.

Computed tomography colonography (CTC) is a relatively new technique that is currently challenging more established methods of large bowel imaging. Several workers have suggested CTC surpasses the barium enema and approaches conventional endoscopy for detection of colorectal neoplasia. Accurate diagnosis relies on technically good studies, the main aim of which is adequate bowel cleansing and distension. Furthermore, the learning curve is steep and normal colonic anatomy has to be re-learned in a CT context. This review aims to describe the technique, revise the imaging features of both normal and pathological colon, and to highlight potential diagnostic pitfalls and their avoidance.

Alteration of anal sphincter morphology following vaginal delivery revealed by multiplanar anal endosonography.

OBJECTIVE: To assess morphologic change in the anal sphincters in the absence of endosonographic evidence of trauma after vaginal delivery. DESIGN: Prospective observational study. SETTING: District general hospital. POPULATION: Consecutively booked nulliparous pregnant women attending antenatal clinic. METHODS: All women were examined using three-dimensional anal endosonography, simple manometry and had questionnaire assessment of incontinence before and after delivery. MAIN OUTCOME MEASURES: Components of the anal canal were measured in the axial, sagittal and coronal planes and paired pre- and post-delivery examinations were compared. Any changes were related to changes in continence and anal canal manometry. RESULTS: Twenty-two women had a vaginal delivery and no endosonographic evidence of perineal trauma after delivery. After delivery, there was significant shortening of the length of the anterior external anal sphincter [EAS] (mean 21.7 vs 20.5 mm, P = 0.02) when measured in the sagittal plane, which increased in anterior angulation with respect to the axis of the anal canal (10 degrees vs 13.8 degrees, P = 0.03). In the axial plane, no change was seen in the thickness of any of the sphincter components after delivery. None of these morphologic changes correlated with changes in manometry or continence score. CONCLUSIONS: Anal sphincter morphology changes after an otherwise atraumatic vaginal delivery. This change does not correlate with any functional symptoms.

Assessment of third degree tears using three-dimensional anal endosonography with combined anal manometry: a novel technique.

Three-dimensional anal endosonography has enabled sagittal and coronal reconstructions of the anal canal to be matched with longitudinal pressure data, to present a combined picture of structure and function. This novel technique has been applied to a group of women with a clinical diagnosis of a third degree tear. Endosonography showed that only 68% of women had ultrasound evidence of sphincter damage. Anal canal anatomy and pressure profile did not differ significantly between those with and those without sphincter damage, but the anterior external anal sphincter and the puborectalis tended to be shorter and the pressures were lower in those with sphincter disruption.

Endosonographic anatomy of the normal anal canal compared with endocoil magnetic resonance imaging.

PURPOSE: This study was designed to clarify the sonographic anatomy of the normal anal canal by comparison with endoanal magnetic resonance imaging, to determine agreement between these imaging modalities and interobserver error in measuring layer thickness. METHODS: Three-dimensional endosonographic and endocoil magnetic resonance images of the anal canal were obtained in four males and five nulliparous females aged 22 to 34 years. Images were analyzed at similar levels throughout the canal using a graphics-overlay technique to compare sonographic with magnetic resonance images. Measurements were taken at one level for agreement analysis between modalities and for interobserver variability in the measurement of the thickness of the main anal canal layers. RESULTS: The muscularis submucosae ani, muscle bundles in the longitudinal muscle layer, and puboanalis were identified on sonography. The outer border of the external sphincter was demarcated by an interface reflection with ischioanal fat. Clarification of the external sphincter anatomy allowed excellent correlation (Ri = 0.96) for the assessment of thickness. There was excellent correlation for the interobserver measurement of the external and internal sphincters and the submucosal width on endosonography, but there was poor correlation for the longitudinal muscle (0.12). CONCLUSION: The overlay technique has improved endosonographic interpretation, and measurement of external sphincter thickness has been validated both by comparison with magnetic resonance and on interobserver agreement.

Predictive value of impaired evacuation at proctography in diagnosing anismus.

OBJECTIVE: We aimed to determine the positive predictive value of impaired evacuation during evacuation proctography for the subsequent diagnosis of anismus. SUBJECTS AND METHODS: Thirty-one adults with signs of impaired evacuation (defined as the inability to evacuate two thirds of a 120 mL contrast enema within 30 sec) during evacuation proctography underwent subsequent anorectal physiologic testing for anismus. A physiologic diagnosis of anismus was based on a typical clinical history of the condition combined with impaired rectal balloon expulsion or abnormal surface electromyogram. RESULTS: Twenty-eight (90%) of the 31 patients with impaired proctographic evacuation were found to have anismus at subsequent physiologic testing. Among the 28 were all 10 patients who evacuated no contrast medium and all 11 patients with inadequate pelvic floor descent, giving evacuation proctography a positive predictive value of 90% for the diagnosis of anismus. A prominent puborectal impression was seen in only three subjects during proctography, one of whom subsequently showed no physiologic sign of anismus. CONCLUSION: Impaired evacuation during evacuation proctography is highly predictive for diagnosis of anismus.

Assessment of external anal sphincter morphology in idiopathic fecal incontinence with endocoil magnetic resonance imaging.

The failure of external anal sphincter repair may relate to sphincter atrophy where muscle fibers are replaced by fat, seen on MRI due to the differing signals returned by fat and muscle tissue. Manometry, electrophysiology, and MRI with an endocoil were performed on 34 fecally incontinent patients with intact sphincters on endosonography. The area of the external sphincter was measured in the midcoronal plane, and the percentage fat content calculated. Sphincter muscle area correlated strongly with squeeze pressure (P < 0.001) but not with percentage fat content. There was no relationship between percentage fat and age, weight, anal sensation, squeeze pressure, sphincter length or width, or pudendal nerve terminal motor latency. There was a trend for smaller sphincters to contain a higher percentage fat content (P = 0.059). MRI has established a relationship between function and external sphincter bulk, but not fat content, although smaller muscles may contain more fat.