Automated surgical step recognition in transurethral bladder tumor resection using artificial intelligence: transfer learning across surgical modalities

Objective

Automated surgical step recognition (SSR) using AI has been a catalyst in the "digitization" of surgery. However, progress has been limited to laparoscopy, with relatively few SSR tools in endoscopic surgery. This study aimed to create a SSR model for transurethral resection of bladder tumors (TURBT), leveraging a novel application of transfer learning to reduce video dataset requirements.

Materials and methods

Retrospective surgical videos of TURBT were manually annotated with the following steps of surgery: primary endoscopic evaluation, resection of bladder tumor, and surface coagulation. Manually annotated videos were then utilized to train a novel AI computer vision algorithm to perform automated video annotation of TURBT surgical video, utilizing a transfer-learning technique to pre-train on laparoscopic procedures. Accuracy of AI SSR was determined by comparison to human annotations as the reference standard.

Results

A total of 300 full-length TURBT videos (median 23.96 min; IQR 14.13-41.31 min) were manually annotated with sequential steps of surgery. One hundred and seventy-nine videos served as a training dataset for algorithm development, 44 for internal validation, and 77 as a separate test cohort for evaluating algorithm accuracy. Overall accuracy of AI video analysis was 89.6%. Model accuracy was highest for the primary endoscopic evaluation step (98.2%) and lowest for the surface coagulation step (82.7%).

Conclusion

We developed a fully automated computer vision algorithm for high-accuracy annotation of TURBT surgical videos. This represents the first application of transfer-learning from laparoscopy-based computer vision models into surgical endoscopy, demonstrating the promise of this approach in adapting to new procedure types.

Cancer Detection Rate and Abnormal Interpretation Rate of Prostate MRI in Patients With Low-Grade Cancer

PURPOSE

The aim of this study was to evaluate the utility of cancer detection rate (CDR) and abnormal interpretation rate (AIR) in prostate MRI for patients with low-grade prostate cancer (PCa).

METHODS

This three-center retrospective study included patients who underwent prostate MRI from 2017 to 2021 with known low-grade PCa (Gleason score 6) without prior treatment. Patient-level highest Prostate Imaging Reporting & Data System (PI-RADS®) score and pathologic diagnosis within 1 year after MRI were used to evaluate the diagnostic performance of prostate MRI in detecting clinically significant PCa (csPCa; Gleason score ≥ 7). The metrics AIR, CDR, and CDR adjusted for pathologic confirmation rate were calculated. Radiologist-level AIR-CDR plots were shown. Simulation AIR-CDR lines were created to assess the effects of different diagnostic performances of prostate MRI and the prevalence of csPCa.

RESULTS

A total of 3,207 examinations were interpreted by 33 radiologists. Overall AIR, CDR, and CDR adjusted for pathologic confirmation rate at PI-RADS 3 to 5 (PI-RADS 4 and 5) were 51.7% (36.5%), 22.1% (18.8%), and 30.7% (24.6%), respectively. Radiologist-level AIR and CDR at PI-RADS 3 to 5 (PI-RADS 4 and 5) were in the 36.8% to 75.6% (21.9%-57.5%) range and the 16.3%-28.7% (10.9%-26.5%) range, respectively. In the simulation, changing parameters of diagnostic performance or csPCa prevalence shifted the AIR-CDR line.

CONCLUSIONS

The authors propose CDR and AIR as performance metrics in prostate MRI and report reference performance values in patients with known low-grade PCa. There was variability in radiologist-level AIR and CDR. Combined use of AIR and CDR could provide meaningful feedback for radiologists to improve their performance by showing relative performance to other radiologists.

Cancer Detection Rate and Abnormal Interpretation Rate of Prostate MRI Performed for Clinical Suspicion of Prostate Cancer

PURPOSE

To report cancer detection rate (CDR) and abnormal interpretation rate (AIR) in prostate MRI performed for clinical suspicion of prostate cancer (PCa).

MATERIALS AND METHODS

This retrospective single-institution, three-center study included patients who underwent MRI for clinical suspicion of PCa between 2017 and 2021. Patients with known PCa were excluded. Patient-level Prostate Imaging-Reporting and Data System (PI-RADS) score was extracted from the radiology report. AIR was defined as number of abnormal MRI (PI-RADS score 3-5) / total number of MRIs. CDR was defined as number of clinically significant PCa (csPCa: Gleason score ≥7) detected at abnormal MRI / total number of MRI. AIR, CDR, and CDR adjusted for pathology confirmation rate were calculated for each of three centers and pre-MRI biopsy status (biopsy-naive and previous negative biopsy).

RESULTS

A total of 9,686 examinations (8,643 unique patients) were included. AIR, CDR, and CDR adjusted for pathology confirmation rate were 45.4%, 23.8%, and 27.6% for center I; 47.2%, 20.0%, and 22.8% for center II; and 42.3%, 27.2%, and 30.1% for center III, respectively. Pathology confirmation rate ranged from 81.6% to 88.0% across three centers. AIR and CDR for biopsy-naive patients were 45.5% to 52.6% and 24.2% to 33.5% across three centers, respectively, and those for previous negative biopsy were 27.2% to 39.8% and 11.7% to 14.2% across three centers, respectively.

CONCLUSION

We reported CDR and AIR in prostate MRI for clinical suspicion of PCa. CDR needs to be adjusted for pathology confirmation rate and pre-MRI biopsy status for interfacility comparison.

Decreased prostate MRI cancer detection rate due to moderate to severe susceptibility artifacts from hip prosthesis

OBJECTIVES

To evaluate the impact of susceptibility artifacts from hip prosthesis on cancer detection rate (CDR) in prostate MRI.

MATERIALS AND METHODS

This three-center retrospective study included prostate MRI studies for patients without known prostate cancer between 2017 and 2021. Exams with hip prosthesis were searched on MRI reports. The degree of susceptibility artifact on diffusion-weighted images was retrospectively categorized into mild, moderate, and severe (> 66%, 33-66%, and < 33% of the prostate volume are evaluable) by blind reviewers. CDR was defined as the number of exams with Gleason score ≥7 detected by MRI (PI-RADS ≥3) divided by the total number of exams. For each artifact grade, control exams without hip prosthesis were matched (1:6 match), and CDR was compared. The degree of CDR reduction was evaluated with ratio, and influential factors were evaluated by expanding the equation.

RESULTS

Hip arthroplasty was present in 548 (4.8%) of the 11,319 MRI exams. CDR of the cases and matched control exams for each artifact grade were as follows: mild (n = 238), 0.27 vs 0.25, CDR ratio = 1.09 [95% CI: 0.87-1.37]; moderate (n = 143), 0.18 vs 0.27, CDR ratio = 0.67 [95% CI: 0.46-0.96]; severe (n = 167), 0.22 vs 0.28, CDR ratio = 0.80 [95% CI: 0.59-1.08]. When moderate and severe artifact grades were combined, CDR ratio was 0.74 [95% CI: 0.58-0.93]. CDR reduction was mostly attributed to the increased frequency of PI-RADS 1-2.

CONCLUSION

With moderate to severe susceptibility artifacts from hip prosthesis, CDR was decreased to 74% compared to the matched control.

CLINICAL RELEVANCE STATEMENT

Moderate to severe susceptibility artifacts from hip prosthesis may cause a non-negligible CDR reduction in prostate MRI. Expanding indications for systematic prostate biopsy may be considered when PI-RADS 1-2 was assigned.

KEY POINTS

• We proposed cancer detection rate as a diagnostic performance metric in prostate MRI. • With moderate to severe susceptibility artifacts secondary to hip arthroplasty, cancer detection rate decreased to 74% compared to the matched control. • Expanding indications for systematic prostate biopsy may be considered when PI-RADS 1-2 is assigned.

Impact of Prostate Cancer Treatment with Low Dose Rate Brachytherapy on Testosterone: A Retrospective Analysis

PURPOSE/OBJECTIVE(S)

Decrease in serum testosterone counts have been reported in the literature following external beam radiotherapy (EBRT), with a suggested association to low dose irradiation of the testes occurring with historical and modern external techniques. Low dose rate (LDR) brachytherapy has been described as exposing the testes to between 2 and 19 cGy compared with 196-220 cGy with EBRT. This decrease in excess dose is hypothesized to spare post-treatment testosterone decrease and subsequent change in patient-perceived quality of life. Here, we retrospectively evaluate LDR-treated prostate cancer patient testosterone change in a single-institution patient cohort.

MATERIALS/METHODS

Patients with prostate cancer who had previously received LDR brachytherapy were identified, and patients with prior baseline total testosterone lab values as well as a lab value within one year post-treatment were identified. Patients receiving concurrent androgen deprivation therapy or EBRT were excluded. The closest baseline values prior to and after LDR treatment were used for before/after comparison. Samples were compared using the paired t-test.

RESULTS

A total of 1,463 patients receiving LDR were identified with data available for analysis between 1998 and 2023; of these, 139 patients met the above criteria for analysis. Mean age was 66 (median 67; range: 47 - 79). 5 patients received 110 Gy, 2 received 120 Gy, and the remainder 145 Gy, all conducted with I-125. Total mCi delivered ranged from 20.3 mCi to 56.7 mCi (median 37.6 mCi). Approximately 57% were GS6, 42% G7, and < 1% G8. Approximately 80% of patients had T1c disease, with 19% T2 and < 1% T3a. All patients were cN0M0. Mean pre- and post-treatment testosterone were 385.5 ng/dL and 382.9 (SD: 170.9, 150.9; mean difference 2.65 [95% CI: -15.6, 20.9]), respectively, with no statistical change noted (p = 0.774).

CONCLUSION

Testosterone levels have been reported to drop following definitive EBRT owing to excess dose delivery to the testes. On review of our institutional experience in definitive LDR brachytherapy for patients treated without ADT administration, no change in testosterone levels were noted.

ReIMAGINE Prostate Cancer Screening Study: protocol for a single-centre feasibility study inviting men for prostate cancer screening using MRI

INTRODUCTION

The primary objective of the ReIMAGINE Prostate Cancer Screening Study is to explore the uptake of an invitation to prostate cancer screening using MRI.

METHODS AND ANALYSIS

The ReIMAGINE Prostate Cancer Screening Study is a prospective single-centre feasibility study. Eligible men aged 50-75 years with no prior prostate cancer diagnosis or treatment will be identified through general practitioner practices and randomly selected for invitation. Those invited will be offered an MRI scan and a prostate-specific antigen (PSA) blood test. The screening MRI scan consists of T2-weighted, diffusion-weighted and research-specific sequences, without the use of intravenous contrast agents. Men who screen positive on either MRI or PSA density will be recommended to have standard of care (National Health Service) tests for prostate cancer assessment, which includes multiparametric MRI. The study will assess the acceptability of an MRI-based prostate screening assessment and the prevalence of cancer detected in MRI-screened men. Summary statistics will be used to explore baseline characteristics in relation to acceptance rates and prevalence of cancer.

ETHICS AND DISSEMINATION

ReIMAGINE Prostate Cancer Screening is a single-site screening study to assess the feasibility of MRI as a screening tool for prostate cancer. Ethical approval was granted by London-Stanmore Research Ethics Committee Heath Research Authority (reference 19/LO/1129). Study results will be published in peer-reviewed journals after completion of data analysis and used to inform the design of a multicentre screening study in the UK.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT04063566).

How informed is our consent? Patient awareness of radiation and radical prostatectomy complications

OBJECTIVE

To evaluate patient's recall of pretreatment counseling for radical prostatectomy and radiation therapy for the treatment of prostate cancer.

MATERIAL AND METHODS

A retrospective review of all patients presenting to our reconstructive urology clinic for the management of the complications of prostate cancer treatment was conducted over 24 months. Patients treated with only surgery or radiotherapy were included in the study. Patients were asked a standard series of questions to assess their recall of their pre-prostate cancer treatment counseling.

RESULTS

We identified 206 patients that met inclusion criteria. Of those, 153 underwent radical prostatectomy and 53 patients received radiation therapy. Median age at presentation was 72 years in the surgery group and 75 in the radiation therapy group. Mean time since treatment was 8.8 years in those that recalled being counseled and 9.9 years in those who did not (p=0.21). In the surgery group, the adverse effects experienced by 119 (77.8%) patients recalled, and counselled were related to the risk of treatment. In the surgical patients that had records with documentation of pretreatment counseling, 41/48 (85.4%) endorsed recall. In the surgery group, 117 (76.5%) stated that their treating physician was aware of their complication. In the radiation group, 5 patients (9.4%) endorsed recall (p<0.0001). In the subgroup of radiation patients with documentation of pre-treatment counseling, no patients endorsed recall. In the surgery group, 117 (76.5%) patients stated that their treating physicians were aware of their complication, while in the radiation group, only 16 (30.2%) of treating physicians were aware of the complications (p<0.0001).

CONCLUSION

Patient recall of potential complications of prostate cancer treatment is poor. It's unclear if this is secondary to poor recall, selective memory loss or inadequate counseling.

Long-term Efficacy of Holmium Laser Enucleation of the Prostate in Patients With Detrusor Underactivity or Acontractility

OBJECTIVE

To evaluate long-term outcomes for men with benign prostatic obstruction (BPO) and concurrent detrusor underactivity (DUA) or acontractility following holmium laser enucleation of the prostate (HoLEP).

METHODS

A retrospective chart review was performed on all patients with BPO and urodynamic evidence of DUA or acontractility secondary to a nonneurogenic etiology that underwent HoLEP at our institution over a 4-year period. Patients were included if they had at least 24 months of follow-up.

RESULTS

We identified 9 patients with DUA and 8 patients with acontractility who met inclusion criteria with median ages of 76 and 75 years, respectively. Preoperatively, 7 (77.8%) men with DUA and 8 (100%) men with acontractility had catheter-dependent urinary retention for a median of 2 and 5 months, respectively. Postoperatively, 8 (88.9%) men with DUA and 5 (62.5%) men with acontractility were catheter free, with a median follow-up of 50.9 and 38.6 months, respectively. All the men requiring catheterization were voiding spontaneously, but used intermittent catheterization for elevated postvoid residuals.

CONCLUSION

HoLEP appears to be an effective surgical option for patients with BPO and detrusor hypocontractility or acontractility, with durable results at follow-up greater than 24 months. However, patients with acontractile bladders should be counseled on possible need to for intermittent catheterization that may be needed for high postvoid residuals.

Uterine artery pulsatility and resistivity indices in pregnancy: Comparison of MRI and Doppler US

OBJECTIVE

The aim of this work was to evaluate whether the uterine arteries (UtA) could be identified and their flow profiles measured during a fetal MRI examination. A comparison was performed against same day sonographic Doppler assessment.

METHODS

35 normal, healthy, singleton pregnancies at 28-32 weeks gestation underwent routine Doppler examination, followed by MRI examination. The resistivity index (RI) and pulsatility index (PI) of the left and right UtA were measured using phase contrast MRI. Bland Altman statistics were used to compare MRI and ultrasound results.

RESULTS

Sixty-nine comparable vessels were analysed. Six vessels were excluded due to artefact or technical error. Bland-Altman analysis demonstrated the ultrasound indices were comparable, although systematically lower than the MRI indices; Right UtA RI bias -0.03 (95% limits of agreement (LOA) -0.27 to +0.20), and left UtA RI bias -0.06 (95% LOA -0.26 to +0.14); Right UtA PI bias -0.06 (95% LOA -0.50 to +0.38), Left UtA PI bias -0.11 (95% LOA -0.54 to +0.32). The inter-rater agreement for the MRI derived PI and RI analysis was good.

CONCLUSION

This study demonstrates that in the majority of early third trimester pregnancies, the uterine arteries can be identified, and their flow profiles measured using MRI, and that the derived PI and RI values are comparable with Doppler ultrasound values.

Prospective study evaluating the relative sensitivity of 18F-NaF PET/CT for detecting skeletal metastases from renal cell carcinoma in comparison to multidetector CT and 99mTc-MDP bone scintigraphy, using an adaptive trial design

BACKGROUND

The detection of occult bone metastases is a key factor in determining the management of patients with renal cell carcinoma (RCC), especially when curative surgery is considered. This prospective study assessed the sensitivity of (18)F-labelled sodium fluoride in conjunction with positron emission tomography/computed tomography ((18)F-NaF PET/CT) for detecting RCC bone metastases, compared with conventional imaging by bone scintigraphy or CT.

PATIENTS AND METHODS

An adaptive two-stage trial design was utilized, which was stopped after the first stage due to statistical efficacy. Ten patients with stage IV RCC and bone metastases were imaged with (18)F-NaF PET/CT and (99m)Tc-labelled methylene diphosphonate ((99m)Tc-MDP) bone scintigraphy including pelvic single photon emission computed tomography (SPECT). Images were reported independently by experienced radiologists and nuclear medicine physicians using a 5-point scoring system.

RESULTS

Seventy-seven lesions were diagnosed as malignant: 100% were identified by (18)F-NaF PET/CT, 46% by CT and 29% by bone scintigraphy/SPECT. Standard-of-care imaging with CT and bone scintigraphy identified 65% of the metastases reported by (18)F-NaF PET/CT. On an individual patient basis, (18)F-NaF PET/CT detected more RCC metastases than (99m)Tc-MDP bone scintigraphy/SPECT or CT alone (P = 0.007). The metabolic volumes, mean and maximum standardized uptake values (SUV mean and SUV max) of the malignant lesions were significantly greater than those of the benign lesions (P < 0.001).

CONCLUSIONS

(18)F-NaF PET/CT is significantly more sensitive at detecting RCC skeletal metastases than conventional bone scintigraphy or CT. The detection of occult bone metastases could greatly alter patient management, particularly in the context when standard-of-care imaging is negative for skeletal metastases.

A new CT grading system for hip osteoarthritis

OBJECTIVES

We have developed a new grading system for hip osteoarthritis using clinical computed tomography (CT). This technique was compared with Kellgren and Lawrence (K&L) grading and minimum joint space width (JSW) measurement in digitally reconstructed radiographs (DRRs) from the same CT data. In this paper we evaluate and compare the accuracy and reliability of these measures in the assessment of radiological disease.

DESIGN

CT imaging of hips from 30 female volunteers aged 66 ± 17 years were used in two reproducibility studies, one testing the reliability of the new system, the other testing K&L grading and minimum JSW measurement in DRRs.

RESULTS

Intra- and inter-observer reliability was substantial for CT grading according to weighted kappa (0.74 and 0.75 respectively), while intra- and inter-observer reliability was at worst moderate (0.57) and substantial (0.63) respectively for DRR K&L grading. Bland-Altman analysis showed a systematic difference in minimum JSW measurement of 0.82 mm between reviewers, with a least detectable difference of 1.06 mm. The area under the curve from ROC analysis was 0.91 for our CT composite score.

CONCLUSIONS

CT grading of hip osteoarthritis (categorised as none, developing and established) has substantial reliability. Sensitivity was increased when CT features of osteoarthritis were assigned a composite score (0 = none to 7 = severest) that also performed well as a diagnostic test, but at the cost of reliability. Having established feasibility and reliability for this new CT system, sensitivity testing and validation against clinical measures of hip osteoarthritis will now be performed.

Severity mapping of the proximal femur: a new method for assessing hip osteoarthritis with computed tomography

OBJECTIVE

Plain radiography has been the mainstay of imaging assessment in osteoarthritis for over 50 years, but it does have limitations. Here we present the methodology and results of a new technique for identifying, grading, and mapping the severity and spatial distribution of osteoarthritic disease features at the hip in 3D with clinical computed tomography (CT).

DESIGN

CT imaging of 456 hips from 230 adult female volunteers (mean age 66 ± 17 years) was reviewed using 3D multiplanar reformatting to identify bone-related radiological features of osteoarthritis, namely osteophytes, subchondral cysts and joint space narrowing. Scoresheets dividing up the femoral head, head-neck region and the joint space were used to register the location and severity of each feature (scored from 0 to 3). Novel 3D cumulative feature severity maps were then created to display where the most severe disease features from each individual were anatomically located across the cohort.

RESULTS

Feature severity maps showed a propensity for osteophytes at the inferoposterior and superolateral femoral head-neck junction. Subchondral cysts were a less common and less localised phenomenon. Joint space narrowing <1.5 mm was recorded in at least one sector of 83% of hips, but most frequently in the posterolateral joint space.

CONCLUSIONS

This is the first description of hip osteoarthritis using unenhanced clinical CT in which we describe the co-localisation of posterior osteophytes and joint space narrowing for the first time. We believe this technique can perform several important roles in future osteoarthritis research, including phenotyping and sensitive disease assessment in 3D.

DCE and DW MRI in monitoring response to androgen deprivation therapy in patients with prostate cancer: a feasibility study

Androgen deprivation therapy (ADT) is a key primary treatment for advanced and metastatic prostate cancer and is an important neoadjuvant before radiotherapy. We evaluated 3.0 T dynamic contrast-enhanced MRI and diffusion-weighted (DW) MRI in monitoring ADT response. Twenty-three consecutive patients with prostate cancer treated by primary ADT were included. Imaging was performed at baseline and 3 months posttreatment with ADT. After 3 months therapy there was a significant reduction in all dynamic contrast-enhanced MRI parameters measured in tumor regions of interest (K(trans), k(ep), v(p), IAUGC-90); P < 0.001. Areas of normal-appearing peripheral zone showed no significant change; P = 0.285-0.879. Post-ADT, there was no significant change in apparent diffusion coefficient values in tumors, whilst apparent diffusion coefficient values significantly decreased in areas of normal-appearing peripheral zone, from 1.786 × 10(-3) mm(2) /s to 1.561 × 10(-3) mm(2) /s; P = 0.007. As expected the median Prostate-Specific Antigen (PSA) significantly reduced from 30 ng/mL to 1.5 ng/mL posttreatment, and median prostate volume dropped from 47.6 cm(3) to 24.9 cm(3) ; P < 0.001. These results suggest that dynamic contrast-enhanced MRI and diffusion-weighted MRI offer different information but that both could prove useful adjuncts to the anatomical information provided by T2-weighted imaging. dynamic contrast-enhanced as a marker of angiogenesis may help demonstrate ADT resistance and diffusion-weighted imaging may be more accurate in determining presence of tumor cell death versus residual tumor.

Vascular invasion in hepatocellular carcinoma: is there a correlation with MRI?

OBJECTIVE

Hepatocellular carcinoma (HCC) is one of the commonest malignancies worldwide. Prognosis is predicted by size at diagnosis, vascular invasion and tumour proliferation markers. This study investigates if MRI features of histologically proven HCCs correlate with vascular invasion.

METHODS

Between 2006 and 2008, 18 consecutive patients, with a total of 27 HCCs, had comprehensive MRI studies performed at our institution within a median of 36 days of histology sampling. Each lesion was evaluated independently on MRI by 3 radiologists (blinded to both the radiology and histopathology reports) using a 5-point confidence scale for 23 specific imaging features. The mean of the rating scores across readers was calculated to determine interobserver consistency. The most consistent features were then used to examine the value of features in predicting vascular invasion, using a χ(2 )test for trend, having eliminated those features without sufficient variability.

RESULTS

22 of the 23 imaging features showed sufficient variability across lesions. None of these significantly correlated with the presence of vascular invasion, although a trend was identified with the presence of washout in the portal venous phase on MRI and the median size of lesions, which was greater with vascular invasion.

CONCLUSION

This study suggests that no single MRI feature accurately predicts the presence of vascular invasion in HCCs, although a trend was seen with the presence of washout in the portal venous phase post gadolinium. Larger prospective studies are required to investigate this further.

Minimally-invasive fetal autopsy using magnetic resonance imaging and percutaneous organ biopsies: clinical value and comparison to conventional autopsy

OBJECTIVES

Autopsy is an important investigation following fetal death or termination for fetal abnormality. Postmortem magnetic resonance imaging (MRI) can provide macroscopic information of comparable quality to that of conventional autopsy in the event of perinatal death. It does not provide tissue for histological examination, which may limit the quality of counseling for recurrence risks and elucidation of the cause of death. We sought to examine the comparability and clinical value of a combination of postmortem MRI and percutaneous fetal organ biopsies (minimally invasive autopsy (MIA)) with conventional fetal autopsy.

METHODS

Forty-four fetuses underwent postmortem MRI and attempted percutaneous biopsy (using surface landmarks) of major fetal organs (liver, lung, heart, spleen, kidney, adrenal and thymus) following fetal death or termination for abnormality, prior to conventional autopsy, which was considered the 'gold standard'. We compared significant findings of the two examinations for both diagnostic information and clinical significance. Ancillary investigations (such as radiographs and placental histology) were regarded as common to the two forms of autopsy.

RESULTS

In 21 cases conventional autopsy provided superior diagnostic information to that of MIA. In two cases the MIA provided superior diagnostic information to that of conventional autopsy, when autolysis prevented detailed examination of the fetal brain. In the remaining 21 cases, conventional autopsy and MIA provided equivalent diagnostic information. With regard to clinical significance, however, in 32 (72.7%) cases, the MIA provided information of at least equivalent clinical significance to that of conventional autopsy. In no case did the addition of percutaneous biopsies reveal information of additional clinical significance.

CONCLUSIONS

Although in some cases MRI may provide additional information, conventional perinatal autopsy remains the gold standard for the investigation of fetal death. The utility of adding percutaneous organ biopsies, without imaging guidance, to an MRI-based fetal autopsy remains unproven. Postmortem MRI, combined with ancillary investigations such as placental histology, external examination by a pathologist, cytogenetics and plain radiography provided information of equivalent clinical significance in the majority of cases.

Accuracy of hepatocellular carcinoma detection on multidetector CT in a transplant liver population with explant liver correlation

AIM

To evaluate the diagnostic accuracy of multidetector computed tomography (MDCT) for hepatocellular carcinoma (HCC) in cirrhotic patients undergoing liver transplantation. Secondary aims were to examine the effect of radiologist experience and lesion size on diagnostic accuracy.

MATERIALS AND METHODS

Thirty-nine patients (72% male with a mean age of 56.5 years) underwent liver transplantation following preoperative triple-phase MDCT examination of the liver. MDCT examinations were retrospectively independently reviewed by three radiologists for the presence and location of suspected HCCs, with the diagnostic confidence recorded using a five-point confidence scale. MDCT examinations were compared with explant specimens for histopathological correlation.

RESULTS

Histopathological results demonstrated 46 HCCs in 29 of the 39 patients. Analysis demonstrated a sensitivity of 65-75% and specificity of 47-88% for detection of HCC lesions. The sensitivity dropped to 48-57% for lesions of size ≤20mm. As the diagnostic confidence increased, there was a further decrease in the sensitivity (4-26%). The radiologist with the greatest number of years experience was found to have a significantly higher accuracy of detection of HCC lesions compared with the least experienced radiologist.

CONCLUSION

Larger lesion size of HCC and greater number of years experience of the radiologist resulted in significantly higher accuracy of HCC lesion detection. The overall sensitivity and specificity results for MDCT detection of HCC are comparable to previous helical CT imaging.

Accuracy of hepatocellular carcinoma detection on multidetector CT in a transplant liver population with explant liver correlation

AIM

To evaluate the diagnostic accuracy of multidetector computed tomography (MDCT) for hepatocellular carcinoma (HCC) in cirrhotic patients undergoing liver transplantation. Secondary aims were to examine the effect of radiologist experience and lesion size on diagnostic accuracy.

MATERIALS AND METHODS

Thirty-nine patients (72% male with a mean age of 56.5 years) underwent liver transplantation following preoperative triple-phase MDCT examination of the liver. MDCT examinations were retrospectively independently reviewed by three radiologists for the presence and location of suspected HCCs, with the diagnostic confidence recorded using a five-point confidence scale. MDCT examinations were compared with explant specimens for histopathological correlation.

RESULTS

Histopathological results demonstrated 46 HCCs in 29 of the 39 patients. Analysis demonstrated a sensitivity of 65-75% and specificity of 47-88% for detection of HCC lesions. The sensitivity dropped to 48-57% for lesions of size ≤20mm. As the diagnostic confidence increased, there was a further decrease in the sensitivity (4-26%). The radiologist with the greatest number of years experience was found to have a significantly higher accuracy of detection of HCC lesions compared with the least experienced radiologist.

CONCLUSION

Larger lesion size of HCC and greater number of years experience of the radiologist resulted in significantly higher accuracy of HCC lesion detection. The overall sensitivity and specificity results for MDCT detection of HCC are comparable to previous helical CT imaging.

MR sialography: the effect of a sialogogue and ductal occlusion in volunteers

MR sialography using heavily T(2) weighted projection techniques relies upon saliva for image contrast, and the visualization of normal ducts is often limited. Methods used to increase the volume of intraductal saliva during imaging in order to improve duct visualization have not been previously evaluated. The effect of a sialogogue and passive ductal occlusion on the ability to visualize the main and intraglandular salivary gland ducts during MR sialography was investigated. Three-dimensional (3D) T(2) weighted MR sialograms were obtained from 12 healthy volunteers with and without the combined use of a sialogogue and passive ductal occlusion pad adjacent to the parotid duct orifice on one side. Two radiologists (in consensus) subjectively evaluated ductal visualization and image artefacts on the resulting blinded maximum intensity projections. The results demonstrate that main duct visualization was significantly improved (p<0.00001) by this technique, with no significant change seen in image artefacts. Although an improvement in intraglandular duct visualization was noted, this was not statistically significant (p = 0.05). Thus, the use of a sialogogue and passive ductal occlusion improves visualization of the main parotid duct in volunteers undergoing MR sialography. Further optimization and evaluation of this approach should lead to improvements in the MR sialography examination of patients.

Postmortem fetal organ volumetry using magnetic resonance imaging and comparison to organ weights at conventional autopsy

OBJECTIVES

Following perinatal death, organ weights at autopsy may provide evidence of growth restriction and pulmonary hypoplasia. Whilst postmortem magnetic resonance imaging (MRI) may provide comparable information to autopsy about structural abnormalities, its ability to provide reproducible data about organ size has yet to be determined. We examined the feasibility of using postmortem MRI to provide estimates of organ size and weight.

METHODS

Twenty-five fetuses of gestational age from 16 to 40 weeks underwent postmortem MRI prior to autopsy. Fetal lung, brain and liver volume estimations were performed by two observers using the stereology technique on postmortem MRI slices. Fetal lung, brain and liver weights were recorded at autopsy. Organ volume estimates and autopsy organ weights were compared using regression analysis, and estimates of fetal organ densities made. Interobserver variability was assessed using a Bland-Altman plot. Receiver-operating characteristics curve (ROC) analysis compared MRI brain : liver volume ratios to autopsy brain : liver weight ratios.

RESULTS

A linear relationship between organ volume estimates and organ weight was observed. Estimated densities for the fetal brain, liver and lung were 1.08 g/cm(3), 1.15 g/cm(3) and 1.15 g/cm(3), respectively. Interobserver 5th and 95th percentile limits of agreement for fetal brain, liver and lung were - 5.4% to + 7.9%, - 11.8% to + 8.3% and - 14.3% to + 8.7%, respectively. For MRI organ volumes to detect a brain weight : liver weight ratio > or = 4, ROC analysis demonstrated an area under the curve of 0.61, with an optimal cut-off of 4.1.

CONCLUSION

Postmortem MRI organ volumetry can be used to estimate weights of major fetal organs. This may increase the information obtained from a minimally-invasive perinatal autopsy, particularly in the context of pulmonary hypoplasia and intrauterine growth restriction, where differential organ growth plays a major part in assessment of the underlying pathology.

Use of a confidence scale in reporting postmortem fetal magnetic resonance imaging

OBJECTIVES

Postmortem magnetic resonance imaging (MRI) may be an alternative to conventional autopsy. However, it is unclear how confident radiologists are in reporting such studies. We sought to determine the confidence with which radiologists report on various fetal organs by developing a scale to express their confidence of normality and abnormality, and to place this in the context of a pathological diagnosis of whether the organ was in fact normal or abnormal.

METHODS

Thirty fetuses, aged 16-39 gestational weeks and weighing 61-3270 g, underwent postmortem MRI prior to conventional autopsy. MRI studies were reported by two radiologists with access to the clinical and sonographic history: a neuroradiologist, reporting head and neck, and a pediatric radiologist, reporting thorax, abdomen and pelvis. Radiologists used a scale (0 = definitely abnormal, 100 = definitely normal, 50 = unable to comment) to indicate their confidence of anatomical structures being normal or abnormal, using a checklist. Conventional autopsies were performed by pediatric pathologists blinded to the MRI findings, and these were considered the reference standard.

RESULTS

Most normal fetal organs had high scores on postmortem MRI, with median confidence scores above 80. However, the atrioventricular valves, duodenum, bowel rotation and pancreas proved more difficult to assess, with median scores of 50, 60, 60 and 62.5, respectively. Abnormal cardiac atria and ventricles, kidneys, cerebral hemispheres and corpus callosum were always detected with high or moderate degrees of confidence (median scores of 2.5, 5, 0, 0 and 30 respectively). However, in two cases with abnormal cardiac outflow tracts, both cases scored 50. Kappa values, assessing agreement between MRI diagnoses of abnormality and autopsy, were high for the brain (0.83), moderate for the lungs (0.56) and fair for the heart (0.33).

CONCLUSIONS

This scoring system represents an attempt to define the confidence of radiologists to report varying degrees of normality and abnormality following z ex-utero fetal MRI. While most fetal anatomy is clearly visualized on postmortem MRI, radiologists may lack confidence reporting such studies and there are particular problems with assessment of some cardiac and gastrointestinal structures, both normal and abnormal.

Low-carbohydrate diet induced reduction of hepatic lipid content observed with a rapid non-invasive MRI technique

Low carbohydrate diets are currently fashionable for inducing weight loss, but the metabolic effects at organ level are not well understood, especially the effect on liver fat storage. Such studies require serial hepatic fat measurements, for which liver biopsy is impractical. In 10 healthy volunteers we demonstrate the use of rapid (total 2 min acquisition time, 10 min magnet room time), non-invasive, quantitative MRI to serially measure hepatic fat changes induced by following a low carbohydrate diet for 10 days. A significant (p<0.01) reduction in hepatic fat after 3 days of dieting was observed in 5 subjects. All subjects demonstrated significant (p<0.01) reductions in hepatic fat by day 10. A strong correlation (kappa = 0.81) existed between the initial fat content and the percentage fat content reduction in the first 3 days of the diet. All subjects lost weight (average 1.7 kg at day 3 and 3.0 kg at day 10), but this was not correlated with hepatic fat loss after 3 days or 10 days of dieting. The results presented illustrate the potential value of MR hepatic fat quantification in longitudinal studies of hepatic fat content.

High-resolution magnetic resonance cholangiography (MRC) with adaptive averaging: diagnostic performance evaluation

AIM

To evaluate the diagnostic performance of an interactive, adaptively averaged (AA) two-dimensional (2D) magnetic resonance cholangiography (MRC) technique in patients with suspected biliary disease by comparison to the standard MRC technique.

MATERIALS AND METHODS

The AA 2D MRC method registers the images after acquisition, allowing summation of multiple images to improve the signal:noise ratio (SNR) and thereby potentially improve the visualization of bile ducts. One hundred and twenty-eight patients underwent both 2D conventional and AA magnetic resonance cholangiopancreatography (MRCP). Twenty-seven patients were excluded from the analysis as AA images could not be properly obtained due to technical failures. All examinations were performed using a 1.5 T whole-body MR system and a four-channel torso phased array coil. Images of 101 patients were adaptively averaged using an in-house developed program written in IDL. Two readers qualitatively evaluated the studies in consensus, blinded to acquisition details and without knowledge of clinical information.

RESULTS

The AA technique was significantly better than the conventional 2D MRC for the visualization of the second-order branch intrahepatic ducts (p<00001). Overall, there was no significant difference in the diagnostic confidence between two techniques (p=0.12). However, the AA technique showed a trend towards more confident diagnosis of biliary strictures (p=0.055), likely due to better diagnostic confidence in identifying second order branch intrahepatic duct strictures (p=0.054).

CONCLUSION

Excluding those patients those patients in whom either satisfactory respiratory gating or a suitable kernel placement was not achieved, AA 2D MRC demonstrated a significant improvement in visualization of intrahepatic duct branches compared to standard MRC.

Influence of perfusion on hepatic MR diffusion measurement

Percutaneous liver biopsy is the current gold standard for the diagnosis and assessment of hepatic fibrosis: it is an uncomfortable procedure with associated risks of infection and internal bleeding. Diffusion-weighted MRI may be important as a non-invasive measure of the grade of hepatic fibrosis, owing to the morphological and physiological changes in hepatic tissues as fibrosis develops. The factors that influence hepatic diffusion measurements are complex and are thought to include hepatic perfusion. This study assesses whether hepatic diffusion measurements are influenced by hepatic perfusion changes as this could be an important variable when investigating the relationship between diffusion measurements and grade of hepatic fibrosis. Hepatic apparent diffusion coefficients (ADCs) were measured in 10 healthy volunteers after an 8-h fast and 1-h after a standard meal (which increases portal vein flow and hepatic sinusoidal perfusion) using a breath-hold technique at b-values of 750, 500 and 200 s/mm(2). ADC measurements using b = 750 and 500 s/mm(2) in the posterior right lobe were unaffected by the perfusion changes (P = 0.15 and 0.14, respectively) whereas the results from the anterior right lobe significantly increased post-prandially (P = 0.03 and 0.008, respectively): inter-subject variability was low ( approximately 5%) for these b-values. Portal perfusion had a significant effect in both the posterior and anterior segments of the right lobe when using a b-value of 200 s/mm(2) (P = 0.01 and 0.00001 respectively): inter-subject variability was found to be high ( approximately 25%). The most reproducible measurements of the ADC can be made in the posterior right lobe and the effect of perfusion is minimised at the higher b-values (b = 500 and 750 s/mm(2)).

Hepatocellular carcinoma tumour thrombus in a re-canalised para-umbilical vein: detection by 18-fluoro-2-deoxyglucose positron emission tomography imaging

This case report describes an unusual site of tumour thrombus in a re-canalised para-umbilical vein, in a patient with hepatocellular carcinoma (HCC) and cirrhosis. The tumour thrombus was suspected on conventional radiography and confirmed using PET imaging, illustrating the complimentary value of structural and functional imaging in achieving the correct diagnosis.

MR colonography: baseline appearance of the unprepared rectosigmoid

A retrospective review of 100 routine pelvic MR examinations was conducted to evaluate the appearance of the unprepared rectosigmoid colon, with the aim of informing future strategies for minimal preparation MR colonography. All examinations were reviewed by two observers in consensus, and included matched-location axial T1 weighted and T2 weighted fat suppressed fast spin echo (FSFSE) images. Analysis revealed that the overall appearance of the faecal material in the colon could simulate tumour in 80% of T1 weighted and 17% of T2 weighted images. By matching the images from the two sequences for each patient the faeces had an overall appearance that would mimic tumour in only 7% of cases. However, luminal tumour-mimicking foci of signal occurred frequently, present in 91% of T1 weighted and 85% of T2 weighted studies. The results indicate that if bowel-cleansing regimens are to be avoided for MR colonography, effective strategies such as dietary restriction and use of oral contrast agents will be required to reduce luminal signal on T2 weighting and eliminate polyp-mimicking foci. The results also suggest that T2 weighted strategies should be further investigated and that combination with T1 weighted imaging may improve discrimination of lesions from normal faecal material.

CO2 as a distending medium for gastric and small bowel MRI: a feasibility study

This work evaluates carbon dioxide as a contrast medium for magnetic resonance imaging of the stomach and small bowel. Twelve healthy volunteers underwent rapid magnetic resonance imaging after oral administration of a carbon dioxide generating agent using a combination of breath-hold and interactive fluoroscopic imaging during breathing. Diagnostic-quality images were obtained in 100% of cases for the stomach and in 92, 75, 67 and 42% of cases for the duodenal segments 1-4, respectively. Visualisation of the jejunum and ileum proved unacceptable for clinical use and anti-peristaltic agents did not significantly influence the results. Further development of fast imaging and magnetic resonance interactive fluoroscopic methods may allow the use of carbon dioxide as a contrast medium for clinical imaging of the stomach and duodenum.

Technical developments in bowel MRI

Magnetic resonance techniques for imaging the gastrointestinal (GI) tract continue to evolve as a result of rapid technical improvement. This review discusses the diagnostic and technical requirements for optimal bowel imaging and to what extent MR is capable of fulfilling these in comparison with established X-ray techniques. New approaches that have recently been demonstrated for the esophagus as well as small and large bowel are described. These developments indicate that MR imaging of the GI tract is likely to make the transition from research development to routine clinical application.

Interactive body magnetic resonance fluoroscopy using modified single-shot half-Fourier rapid acquisition with relaxation enhancement (RARE) with multiparameter control

PURPOSE

To develop a technique for interactive fluoroscopic abdominal magnetic resonance imaging (MRI) based on a single-shot half-Fourier rapid acquisition and relaxation-enhanced sequence.

MATERIALS AND METHODS

The sequence was modified by incorporating inner-volume excitation, driven-equilibrium signal enhancement, and reduced flip angle refocusing pulses. Contrast control was provided by integrating "on-the-fly" selection of phase encoding view order, fat suppression, and section thickness. The resulting sequence was evaluated with phantom experiments to quantify the signal-to-noise ratio (SNR) effects of the modifications and in healthy volunteers for imaging the bile ducts, stomach, and duodenum using water and gaseous contrast media.

RESULTS

Observed SNR relating to driven-equilibrium and flip angle scaling matched theoretical predictions. Volunteer examinations demonstrated the ability of the modified sequence to provide interactive, artifact-free imaging of the abdomen, including switching between conventional proton density-weighted, T2-weighted imaging and "hydrographic" projection imaging.

CONCLUSION

Refinement of this technique may provide an abdomino-pelvic imaging capability similar in concept to real-time ultrasound, but with the advantages of MRI.

MR imaging of the wrist: effect on clinical diagnosis and patient care

PURPOSE

To evaluate the effect of magnetic resonance (MR) imaging of the wrist on clinicians' diagnoses, diagnostic certainty, and patient care.

MATERIALS AND METHODS

A controlled observational study was performed. Referring clinicians completed questionnaires about diagnosis and intended management before and after wrist MR imaging. One hundred eighteen consecutive patients referred for MR imaging of the wrist were recruited from the MR imaging units at a regional teaching hospital and a large district general hospital. The main measures were changes in the clinicians' leading and subsidiary diagnoses after MR imaging, their certainty in these diagnoses, and changes in intended patient care.

RESULTS

Questionnaires were incorrectly completed for five patients, questionnaires were not returned for three, appointments were canceled for 10, and two could not tolerate the MR examination. Complete follow-up data were available for 98 patients. The clinical diagnosis changed in 55 of 98 patients; in the remaining 43 patients, diagnostic certainty increased in 23. Clinicians reported that MR imaging had substantially improved their understanding of the disease in 67 of 98 patients. The care plan changed in 45 of 98 patients, with a shift away from surgical treatment. Twenty-eight patients were discharged without further investigation. MR imaging was similarly effective in the regional teaching center and the district general hospital.

CONCLUSION

MR imaging of the wrist influences clinicians' diagnoses and management plans.

Colon carcinoma: MR imaging with CO2 enema--pilot study

Prior to surgery, seven patients with known colonic tumors underwent breath-hold single-shot fast spin-echo magnetic resonance imaging during a CO2 enema. The images were evaluated for depiction of tumor, adjacent structures, and the remaining colon, and findings were compared with findings at surgery. In all seven patients, the tumor was demonstrated, and in four (57%), breach of the muscularis propria was correctly predicted.

Magnetic resonance cholangiopancreatography

Magnetic resonance imaging can now offer a robust and non-invasive diagnostic alternative to the established imaging investigations of the biliary and pancreatic ducts. This article briefly reviews the underlying principles, technique, pitfalls and clinical applications.

Massive hepatic fibrosis in Gaucher's disease: clinico-pathological and radiological features

Hepatomegaly is frequent in patients with type 1 Gaucher's disease and is associated with infiltration of the liver with pathological macrophages. Most patients suffer no significant clinical consequences, but a few develop portal hypertension which may progress to parenchymal liver failure. We describe four patients with Gaucher's disease who have developed portal hypertension. We have reviewed their clinical histories and all available histological and radiological material. All had severe Gaucher's disease with multi-organ involvement, and had undergone splenectomy in childhood. Histologically, this advanced liver disease was characterized by a picture of extreme and advanced confluent fibrosis occupying the central region of the liver. This massive fibrosis is associated with characteristic radiological appearances. The liver histology in these cases is highly unusual and virtually unknown in other conditions. Our studies indicate that without specific treatment the liver disease is progressive and rapidly fatal. However, institution of enzyme replacement therapy with imiglucerase may have beneficial effects even when the condition is far advanced.

High resolution magnetic resonance imaging of atherosclerosis and the response to balloon angioplasty

OBJECTIVE

To explore the use of high resolution magnetic resonance imaging (MRI) of the popliteal artery in defining atheroscelerotic lesions and to monitor the remodelling response to balloon angioplasty.

METHODS

Four patients (aged 49-67) with symptomatic discrete popliteal artery stenoses, as demonstrated by conventional angiography, underwent balloon angioplasty. MRI of the diseased vessel was performed before and one week, one month, three months, and six months after therapeutic balloon angioplasty. Cine phase contrast MRI was used to estimate blood flow just proximal to the lesion before and after angioplasty.

RESULTS

In all patients the extent of the atherosclerotic plaque could be defined, such that even in segments of vessel which were angiographically "normal", atherosclerotic lesions with cross sectional areas ranging from 49% to 76% of potential lumen area were identified. Following angioplasty, plaque fissuring and local dissection were easily identified and serial changes in lumen diameter, blood flow. and lesion size could be documented.

CONCLUSIONS

High resolution MRI can define the extent of atherosclerotic plaque in the peripheral vasculature and demonstrate the changes that occur with remodelling and restenosis following angioplasty. As a safe, reproducible technique MRI is ideal for assessing plaque and monitoring intervention, but further technological developments will be needed if similar or better images are to be achieved in other vascular beds.

Dual-echo breathhold T(2)-weighted fast spin echo MR imaging of liver lesions

The purpose of this study was to develop a multi-shot dual-echo breathhold fast spin echo technique (DFSE) and compare it with conventional spin echo (T2SE) for T(2)-weighted MR imaging of liver lesions. The DFSE acquisition (EffTE1/EffTE2/TR = 66/143/2100 ms) imaged 5 sections per 17 s breathhold. T2SE imaging (TE1/TE2/TR = 60/120/2500 ms) required 16:55 (min:s) for 14 sections. Both techniques used a receive-only phased-array abdominal multicoil and provided 192 x 256 effective resolution. The results showed first and second echo relative DFSE/T2SE contrast values for 27 representative lesions (15 consecutive patients) were 1.08 +/- 0.05 and 1.16 +/- 0.09 (mean +/- STD mean), respectively. Corresponding CNR values were 1.12 +/- 0.09 and 0.97 +/- 0.12. Overall DFSE was comparable-to-superior to T2SE for lesion sizing and image artifact. DFSE lesion detection was inferior to T2SE's in several patient studies because of decreased conspicuity of lesions located near multicoil edges and because of poor breathhold-to-breathhold reproducibility and lack of breathholding. However both DFSE (and T2SE) provided lesion detection rated to be of diagnostic quality for all patient studies. In conclusion, we found that DFSE provides diagnostically useful dual-echo T(2)-weighted MR liver images in a greatly decreased acquisition time.

Vesicouterine fistula: MRI diagnosis

A case of vesicouterine fistula in a young woman following caesarean section is presented. The diagnosis was established successfully using heavily T2-weighted MRI which clearly demonstrated fluid within the fistula, obviating the need for conventional radiographic contrast examination.

How reliable is modern breast imaging in differentiating benign from malignant breast lesions in the symptomatic population?

AIM

To assess the ability of mammography and ultrasound individually and in combination to predict whether a breast abnormality is benign or malignant in patients with symptomatic breast disease.

MATERIALS AND METHODS

Patients included were those in whom histological confirmation of the abnormality following surgical excision was available. Mammographic and ultrasound appearances were prospectively classified using a four-point scale (1 = no significant lesion, 2 = benign lesion, 3 = possibly malignant, 4 = probably malignant).

RESULTS

Histological confirmation following surgical excision was available in 559 patients, of which 303 were benign and 256 were malignant. The imaging classification was correlated with histology in these 559 lesions. In predicting final histology, the sensitivity and specificity of mammography alone were 78.9 and 82.7%, respectively, of ultrasound alone were 88.9 and 77.9%, respectively, and of mammography and ultrasound in combination were 94.2 and 67.9%, respectively. Only one patient had both a mammogram and ultrasound reported as normal (category 1 for both tests) in whom subsequent histology revealed a carcinoma (0.4% of all carcinomas).

CONCLUSION

We found that the extensive use of ultrasound increases the cancer detection rate in this selected population by 14%.

Small bowel MRI using water as a contrast medium

Magnetic resonance imaging (MRI) of the small bowel has been limited by lack of an adequate luminal contrast medium and problems with image artefacts. In this study we investigate the feasibility of imaging the luminal small bowel using rapid heavily T2w techniques, similar to those used for MR cholangiopancreatography, combined with oral water loading. Eight volunteers were examined after drinking 1-21 of water using serial, multisection, half-Fourier single shot rapid acquisition with relaxation enhancement (RARE) acquisitions. The examinations were continued until the terminal ileum was reached or the water reabsorbed. The results were subjectively assessed for visibility of the small bowel. In all subjects the duodenum, jejunum and ileum were well demonstrated with valvulae conniventes clearly visible. The water column reached the terminal ileum and the caecum in six of the eight subjects but in the remaining two water remained in the small bowel and was ultimately reabsorbed. These preliminary results suggest that with further refinement such an approach may be practical for clinical magnetic resonance imaging of the small bowel.

MR cholangiopancreatography: prospective comparison of a breath-hold 2D projection technique with diagnostic ERCP

The aim of this study was to compare prospectively a breath-hold projection magnetic resonance cholangiopancreatography (MRCP) technique with diagnostic endoscopic retrograde cholangiopancreatography (ERCP). Seventy-six patients with suspected strictures or choledocholithiasis were referred for MRCP and subsequent ERCP examination, which were performed within 4 h of each other. The MRCP technique was performed using fat-suppressed rapid acquisition with relaxation enhancement (RARE) projection images obtained in standardised planes with additional targeted projections as required by the supervising radiologist. Two radiologists (in consensus) assessed the MRCP results prospectively and independently for the presence of bile duct calculi, strictures, non-specific biliary dilatation and pancreatic duct dilatation, and recorded a single primary diagnosis. The ERCP was assessed prospectively and independently by a single endoscopist and used as a gold standard for comparison with MRCP. Diagnostic agreement was assessed by the Kappa statistic. The MRCP technique failed in two patients and ERCP in five. In the remaining 69 referrals ERCP demonstrated normal findings in 23 cases, strictures in 19 cases, choledocholithiasis in 9 cases, non-specific biliary dilatation in 14 cases and chronic pancreatitis in 4 cases. The MRCP technique correctly demonstrated 22 of 23 normal cases, 19 strictures with one false positive (sensitivity 100 %, specificity 98 %), all 9 cases of choledocholithiasis with two false positives (sensitivity 100 %, specificity 97 %), 12 of 14 cases of non-specific biliary dilatation and only 1 of 4 cases of chronic pancreatitis. There was overall good agreement for diagnosis based on a kappa value of 0.88. Breath-hold projection MRCP can provide non-invasively comparable diagnostic information to diagnostic ERCP for suspected choledocholithiasis and biliary strictures and may allow more selective use of therapeutic ERCP.

Magnetic resonance imaging or arthrography of the shoulder: which do patients prefer?

110 consecutive patients were asked about their degree of anxiety (SAI scores), pain (VAS scores) and preferences at various stages before and after imaging in order to determine whether patients with shoulder problems prefer MRI or shoulder arthrography. 88 patients underwent MRI, 42 arthrography and 19 both. Mean levels of anxiety were slightly higher for patients undergoing MRI than those having arthrography, but this difference was not statistically significant. There was a statistically significant (p < 0.03) reduction in anxiety after arthrography, but not following MRI. Pain scores fell for both patient groups while at rest during the imaging procedure compared with their pre-imaging baseline measurement. This was statistically significant (p < 0.03) for MRI, but not for arthrography. A significantly higher proportion (p < 0.001) of patients found MRI unpleasant or extremely unpleasant (20/77) compared with arthrography (3/41). Of the 25 patients who expressed a preference on the basis of past or current experience, 11 preferred MRI and 14 arthrography (NS). There was no significant difference in the proportion of patients who would not allow the test to be repeated (29/73 for MRI, 15/39 for arthrography): Although there were minor differences in both the anxiety and pain experienced by patients undergoing MRI and arthrography, this study did not reveal any firm preference for either investigation.

Non-invasive cholangio-pancreatography by breath-hold magnetic resonance imaging: preliminary results

AIMS

A preliminary comparison of a prototype breath-hold magnetic resonance cholangio-pancreatography (MRCP) technique for non-invasive imaging of the pancreatic and biliary ducts with endoscopic retrograde cholangio-pancreatography (ERCP).

METHOD

Twenty ERCP and MRCP examinations were performed in 19 patients referred for routine ERCP with suspected biliary or pancreatic abnormalities. The MRCP technique employed a modified heavily T2-weighted thick slice RARE sequence that allowed up to three images to be obtained in a 16 second breath-hold. The examinations were reported independently and the findings compared.

RESULTS

MRCP accurately discriminated between patients without obstruction (n = 12) and those with (n = 8) and correctly diagnosed the cause of obstruction (three choledocholithiasis, five malignant stricture). In the 12 patients without obstruction the examinations were concordant in eight. In the remaining four patients MRCP provided more information than the corresponding ERCP study, diagnosing a pseudocyst in one patient and visualizing the entire pancreatic duct in three patients in whom this was not possible at ERCP.

CONCLUSIONS

These preliminary results suggest that a breath-hold MRCP technique may allow the selection of those patients with obstructive lesions that require therapeutic ERCP intervention, and may have the potential to reduce the need for diagnostic ERCP examinations.

Magnetic resonance imaging of the shoulder: assessment of effectiveness

OBJECTIVES

To quantify how magnetic resonance imaging (MRI) influences clinicians' diagnosis, diagnostic confidence and management plans in patients with shoulder problems. To investigate whether such changes are associated with an improvement in health.

METHODS

A prospective observational study on all patients referred to a regional centre for MRI of the shoulder over a 6-month period. Data on diagnosis, diagnostic confidence and proposed management before MRI were compared with diagnoses and actual management after MRI. In addition, short form 36 item (SF-36) health survey data were collected at referral and again 6 months later.

RESULTS

In 86 of 99 MRI referrals there was sufficient clinical data for the patient to enter the study. MRI led to previously unsuspected diagnoses in 20 of 59 patients where the clinicians had provided full diagnostic information before and after the examination. When MRI confirmed the clinical diagnosis, significant improvements in clinicians' diagnostic confidence were found (P < 0.001). MRI led to a change in management (P < 0.05) in 44 (62%) of the 71 patients where full management plans were available. Health survey results were available in 62 patients; although there were some improvements in SF-36 scores, these did not reach statistical significance.

CONCLUSION

Magnetic resonance imaging of the shoulder significantly influences clinicians' diagnoses and management plans. However, patients do not record a statistically significant improvement in health-related quality of life over 6 months.

Magnetic resonance imaging of transverse acoustic strain waves

We describe a phase contrast based MRI technique with high sensitivity to cyclic displacement that is capable of quantitatively imaging acoustic strain waves in tissue-like materials. A formalism for considering gradient waveforms as basis functions to measure arbitrary cyclic motion waveforms is introduced. Experiments with tissue-like agarose gel phantoms show that it is possible to measure small cyclic displacements at a submicron level by an appropriate choice of the applied gradient basis function and to use this capability to observe the spatial and temporal pattern of displacements caused by acoustic strain waves. The propagation characteristics of strain waves are determined by the mechanical properties of the media. It is therefore possible to use this technique to noninvasively estimate material properties such as elastic modulus.