Ultrasound of the gall bladder and biliary tree: part 2

Ultrasound is the modality of choice for the initial assessment of the gall bladder and the biliary tree. This article details normal ultrasound appearances of the biliary tree, as well as appearances of biliary obstruction, biliary cirrhosis, biliary gall-stones, developmental disorders, cholangiopathies and cholangiocarcinoma.

Prostate MRI: evaluating tumor volume and apparent diffusion coefficient as surrogate biomarkers for predicting tumor Gleason score

PURPOSE

To investigate whether tumor volume derived from apparent diffusion coefficient (ADC) maps (VolumeADC) and tumor mean ADC value (ADCmean) are independent predictors of prostate tumor Gleason score (GS).

EXPERIMENTAL DESIGN

Tumor volume and GS were recorded from whole-mount histopathology for 131 men (median age, 60 years) who underwent endorectal diffusion-weighted MRI for local staging of prostate cancer before prostatectomy. VolumeADC and ADCmean were derived from ADC maps and correlated with histopathologic tumor volume and GS. Univariate and multivariate analyses were performed to evaluate prediction of tumor aggressiveness. Areas under receiver-operating characteristics curves (AUC) were calculated to evaluate the performance of VolumeADC and ADCmean in discriminating tumors of GS 6 and GS ≥7.

RESULTS

Histopathology identified 116 tumor foci >0.5 mL. VolumeADC correlated significantly with histopathologic tumor volume (ρ = 0.683). The correlation increased with increasing GS (ρ = 0.453 for GS 6 tumors; ρ = 0.643 for GS 7 tumors; ρ = 0.980 for GS ≥8 tumors). Both VolumeADC (ρ = 0.286) and ADCmean (ρ = -0.309) correlated with GS. At univariate analysis, both VolumeADC (P = 0.0325) and ADCmean (P = 0.0033) could differentiate GS = 6 from GS ≥7 tumor foci. However, at multivariate analysis, only ADCmean (P = 0.0156) was a significant predictor of tumor aggressiveness (i.e., GS 6 vs. GS ≥7). For differentiating GS 6 from GS ≥7 tumors, AUCs were 0.644 and 0.704 for VolumeADC and ADCmean, respectively, and 0.749 for both parameters combined.

CONCLUSION

In patients with prostate cancer, ADCmean is an independent predictor of tumor aggressiveness, but VolumeADC is not. The latter parameter adds little to the ADCmean in predicting tumor GS.

Prostate cancer aggressiveness: assessment with whole-lesion histogram analysis of the apparent diffusion coefficient

PURPOSE

To evaluate the relationship between prostate cancer aggressiveness and histogram-derived apparent diffusion coefficient (ADC) parameters obtained from whole-lesion assessment of diffusion-weighted magnetic resonance (MR) imaging of the prostate and to determine which ADC metric may help best differentiate low-grade from intermediate- or high-grade prostate cancer lesions.

MATERIALS AND METHODS

The institutional review board approved this retrospective HIPAA-compliant study of 131 men (median age, 60 years) who underwent diffusion-weighted MR imaging before prostatectomy for prostate cancer. Clinically significant tumors (tumor volume > 0.5 mL) were identified at whole-mount step-section histopathologic examination, and Gleason scores of the tumors were recorded. A volume of interest was drawn around each significant tumor on ADC maps. The mean, median, and 10th and 25th percentile ADCs were determined from the whole-lesion histogram and correlated with the Gleason score by using the Spearman correlation coefficient (ρ). The ability of each parameter to help differentiate tumors with a Gleason score of 6 from those with a Gleason score of at least 7 was assessed by using the area under the receiver operating characteristic curve (Az).

RESULTS

In total, 116 clinically significant lesions (89 in the peripheral zone, 27 in the transition zone) were identified in 85 of the 131 patients (65%). Forty-six patients did not have a clinically significant lesion. For mean ADC, median ADC, 10th percentile ADC, and 25th percentile ADC, the Spearman ρ values for correlation with Gleason score were -0.31, -0.30, -0.36, and -0.35, respectively, whereas the Az values for differentiating lesions with a Gleason score of 6 from those with a Gleason score of at least 7 were 0.704, 0.692, 0.758, and 0.723, respectively. The Az of 10th percentile ADC was significantly higher than that of the mean ADC for all lesions and peripheral zone lesions (P = .0001).

CONCLUSION

When whole-lesion histograms were used to derive ADC parameters, 10th percentile ADC correlated with Gleason score better than did other ADC parameters, suggesting that 10th percentile ADC may prove to be optimal for differentiating low-grade from intermediate- or high-grade prostate cancer with diffusion-weighted MR imaging.

Areas of normal pulmonary parenchyma on HRCT exhibit increased FDG PET signal in IPF patients

PURPOSE

Patients with idiopathic pulmonary fibrosis (IPF) show increased PET signal at sites of morphological abnormality on high-resolution computed tomography (HRCT). The purpose of this investigation was to investigate the PET signal at sites of normal-appearing lung on HRCT in IPF.

METHODS

Consecutive IPF patients (22 men, 3 women) were prospectively recruited. The patients underwent (18)F-FDG PET/HRCT. The pulmonary imaging findings in the IPF patients were compared to the findings in a control population. Pulmonary uptake of (18)F-FDG (mean SUV) was quantified at sites of morphologically normal parenchyma on HRCT. SUVs were also corrected for tissue fraction (TF). The mean SUV in IPF patients was compared with that in 25 controls (patients with lymphoma in remission or suspected paraneoplastic syndrome with normal PET/CT appearances).

RESULTS

The pulmonary SUV (mean ± SD) uncorrected for TF in the controls was 0.48 ± 0.14 and 0.78 ± 0.24 taken from normal lung regions in IPF patients (p < 0.001). The TF-corrected mean SUV in the controls was 2.24 ± 0.29 and 3.24 ± 0.84 in IPF patients (p < 0.001).

CONCLUSION

IPF patients have increased pulmonary uptake of (18)F-FDG on PET in areas of lung with a normal morphological appearance on HRCT. This may have implications for determining disease mechanisms and treatment monitoring.

Qualitative and quantitative comparison of PET/CT and PET/MR imaging in clinical practice

The aim of this study was to prospectively compare whole-body PET/MR imaging and PET/CT, qualitatively and quantitatively, in oncologic patients and assess the confidence and degree of inter- and intraobserver agreement in anatomic lesion localization.

METHODS

Fifty patients referred for staging with known cancers underwent PET/CT with low-dose CT for attenuation correction immediately followed by PET/MR imaging with 2-point Dixon attenuation correction. PET/CT scans were obtained according to standard protocols (56 ± 20 min after injection of an average 367 MBq of (18)F-FDG, 150 MBq of (68)Ga-DOTATATE, or 333.8 MBq of (18)F-fluoro-ethyl-choline; 2.5 min/bed position). PET/MR was performed with 5 min/bed position. Three dual-accredited nuclear medicine physicians/radiologists identified the lesions and assigned each to an exact anatomic location. The image quality, alignment, and confidence in anatomic localization of lesions were scored on a scale of 1-3 for PET/CT and PET/MR imaging. Quantitative analysis was performed by comparing the standardized uptake values. Intraclass correlation coefficients and the Wilcoxon signed-rank test were used to assess intra- and interobserver agreement in image quality, alignment, and confidence in lesion localization for the 2 modalities.

RESULTS

Two hundred twenty-seven tracer-avid lesions were identified in 50 patients. Of these, 225 were correctly identified on PET/CT and 227 on PET/MR imaging by all 3 observers. The confidence in anatomic localization improved by 5.1% when using PET/MR imaging, compared with PET/CT. The mean percentage interobserver agreement was 96% for PET/CT and 99% for PET/MR imaging, and intraobserver agreement in lesion localization across the 2 modalities was 93%. There was 10% (5/50 patients) improvement in local staging with PET/MR imaging, compared with PET/CT.

CONCLUSION

In this first study, we show the effectiveness of whole-body PET/MR imaging in oncology. There is no statistically significant difference between PET/MR imaging and PET/CT in respect of confidence and degree of inter- and intraobserver agreement in anatomic lesion localization. The PET data on both modalities were similar; however, the observed superior soft-tissue resolution of MR imaging in head and neck, pelvis, and colorectal cancers and of CT in lung and mediastinal nodal disease points to future tailored use in these locations.

PET/MRI: a new technology in the field of molecular imaging

BACKGROUND

The introduction of the new simultaneous PET/MRI scanner opens new opportunities in functional imaging.

SOURCES OF DATA

This article is based on the literature review and our personal experience of the first simultaneous PET/MRI scanner in the UK.

AREAS OF AGREEMENT

PET/CT is well established and a key component of management guidance in a range of diseases. MRI has superior soft tissue resolution, which is useful in the evaluation of many diseases.

AREAS OF CONTROVERSY

There are currently no guidelines regarding clinical use of PET/MRI, and those centres with a PET/MRI facility are undertaking research to look for a 'key application'.

GROWING POINTS AND AREAS TIMELY FOR DEVELOPING RESEARCH

This review briefly describes some of the technical advances, present comparisons with the diagnostic performance of current imaging modalities (PET/CT and MRI) and identifies potential indications and research directions.

Magnetic resonance imaging for predicting prostate biopsy findings in patients considered for active surveillance of clinically low risk prostate cancer

PURPOSE

A barrier to the acceptance of active surveillance for men with prostate cancer is the risk of underestimating the cancer burden on initial biopsy. We assessed the value of endorectal magnetic resonance imaging in predicting upgrading on confirmatory biopsy in men with low risk prostate cancer.

MATERIALS AND METHODS

A total of 388 consecutive men (mean age 60.6 years, range 33 to 89) with clinically low risk prostate cancer (initial biopsy Gleason score 6 or less, prostate specific antigen less than 10 ng/ml, clinical stage T2a or less) underwent endorectal magnetic resonance imaging before confirmatory biopsy. Three radiologists independently and retrospectively scored tumor visibility on endorectal magnetic resonance imaging using a 5-point scale (1-definitely no tumor to 5-definitely tumor). Inter-reader agreement was assessed with weighted kappa statistics. Associations between magnetic resonance imaging scores and confirmatory biopsy findings were evaluated using measures of diagnostic performance and multivariate logistic regression.

RESULTS

On confirmatory biopsy, Gleason score was upgraded in 79 of 388 (20%) patients. Magnetic resonance imaging scores of 2 or less had a high negative predictive value (0.96-1.0) and specificity (0.95-1.0) for upgrading on confirmatory biopsy. A magnetic resonance imaging score of 5 was highly sensitive for upgrading on confirmatory biopsy (0.87-0.98). At multivariate analysis patients with higher magnetic resonance imaging scores were more likely to have disease upgraded on confirmatory biopsy (odds ratio 2.16-3.97). Inter-reader agreement and diagnostic performance were higher for the more experienced readers (kappa 0.41-0.61, AUC 0.76-0.79) than for the least experienced reader (kappa 0.15-0.39, AUC 0.61-0.69). Magnetic resonance imaging performed similarly in predicting low risk and very low risk (Gleason score 6, less than 3 positive cores, less than 50% involvement in all cores) prostate cancer.

CONCLUSIONS

Adding endorectal magnetic resonance imaging to the initial clinical evaluation of men with clinically low risk prostate cancer helps predict findings on confirmatory biopsy and assess eligibility for active surveillance.

Imaging assessment of tumor response: past, present and future

Anatomical response assessment criteria have been in use for decades, with the WHO guidelines being replaced by Response Evaluation Criteria in Solid Tumors (RECIST), updated in 2009 to RECIST 1.1. These methods rely on a change in size of a tumor as the main response criteria, but newer cytostatic agents tend to target tumor function at a molecular level before changing the size of a lesion. Recent modifications, such as the Choi criteria, have improved assessment by taking into account density of tumor, but all of these criteria fail to utilize functional imaging parameters, which are becoming increasingly available, including perfusion CT, perfusion MRI, diffusion-weighted imaging, magnetic resonance spectroscopy, dynamic contrast-enhanced ultrasound and combined PET/computed tomography. Developments in these modalities and standardization of imaging acquisition will help to optimize the next set of response criteria, with inclusion of multiparametric, functional modalities, evaluating tumors at the same molecular level at which they are being targeted by therapeutic agents.

Clinical utility of diffusion-weighted magnetic resonance imaging in prostate cancer

What's known on the subject? and What does the study add? This article reviews what is currently known about diffusion weighted MRI (DW-MRI) in prostate cancer. This mini-review concisely summarises, for clinical managing patients with prostate cancer, the clinical utility of diffusion weighted MRI.

OBJECTIVE

• To review the clinical utility of diffusion-weighted magnetic resonance imaging (DW-MRI) in patients with prostate cancer.

MATERIAL AND METHODS

• The current literature on prostate cancer and DW-MRI was reviewed.

RESULTS

• DW-MRI can be readily acquired on a modern scanner with a short image acquisition time and no need for i.v. contrast medium. • The image contrast is based on the diffusion of water molecules and thus reflects tissue cellularity. • There is increasing evidence that DW- MRI improves the sensitivity and specificity of prostate cancer detection as well as the identification of tumour aggressiveness. • DW-MRI is also showing substantial promise as a response biomarker for both local and metastatic disease

CONCLUSIONS

• DW-MRI is proving to be a useful adjunct to conventional T2-weighted MRI sequences. • The eventual role of DW-MRI in combination with other MRI techniques for multiparametric assessment of prostate cancer needs to be defined further.

Diffusion-weighted magnetic resonance imaging for tumour response assessment: why, when and how?

Diffusion-weighted magnetic resonance imaging (DWI) is increasingly being used to assess tumour response to a variety of anticancer treatments. The technique is quick to perform without the need for administration of exogenous contrast medium, and enables the apparent diffusion coefficient (ADC) of tissues to be quantified. Studies have shown that ADC increases in response to a variety of treatments including chemotherapy, radiotherapy, minimally invasive therapies and novel therapeutics. In this article, we review the rationale of applying DWI for tumour assessment, the evidence for ADC measurements in relation to specific treatments and some of the practical considerations for using ADC to evaluate treatment response.

Abdominal X-ray signs of intra-intestinal drug smuggling

INTRODUCTION

"Body packers" either swallow or insert drug filled packets rectally or vaginally in order to smuggle illicit drugs. AXR is used routinely to screen suspects for the presence of intra-intestinal drug packages. AXR diagnosis can be difficult as stool or gas within the intestine may resemble ingested foreign bodies. We identify the frequency and co-existence of several signs; tic-tac sign, rosette sign, double condom sign, dense surrounding material, density and discover a new sign; parallelism, which will aid in increasing the radiological accuracy.

METHODS

We retrospectively reviewed 285 AXRs performed for suspicion of drug smuggling during the period of March 2006-March 2009 to identify the frequency of these signs.

RESULTS

Of the 285 AXRs performed 59 were positive, 221 negative and five were indeterminate. The tic-tac sign was present in 93%, double condom sign in 73%, dense surrounding wrapping material in 36% and parallelism in 27%. Sixty one percentage of drug packages were iso-dense to faeces and 39% hyperdense. Twenty percentage of the positive abdominal radiographs demonstrated one of the radiographic signs, 39% demonstrated two signs, 32% demonstrated three and 7% four. The most common radiographic sign combination was the tic-tac sign with either dense surrounding material or double condom sign.

CONCLUSION

The most commonly encountered radiographic sign is the tic-tac sign, followed by the double condom sign and dense surrounding material. We also discover a new sign, "parallelism" which although uncommon is highly specific. Accuracy is further increased by comparing the density of packages to faeces and looking for the co-existence of multiple signs.

Predictors of change in walking distance in patients with peripheral arterial disease undergoing endovascular intervention

BACKGROUND

Endovascular treatment of peripheral artery disease is becoming frequent, yet the clinical factors which predict ambulatory outcomes are not known.

HYPOTHESIS

To identify predictors of change in walking distance in patients who underwent endovascular intervention for their lower extremity peripheral arterial disease (PAD).

METHODS

A total of 134 patients underwent lower extremity peripheral arterial intervention, 52 patients were contacted via phone between 1 and 36 months (a mean of 22 mo) after their initial procedure. The remaining 82 patients were excluded due to the following reasons: death (n = 13), contact information was not available (n = 50), and refusal to participate in the follow-up (n = 19).

RESULTS

The patients were 63 +/- 12 years old (mean +/- standard deviation [SD]), 46% were male, 47% were diabetics, 49% had coronary artery disease, of whom 29% had prior revascularization, and 22% had coronary artery bypass grafts (CABG). The disease severity described by Fontaine classification were as follows: 44.2% were in stage II, 15.4% were in stage III, and 40.4% were in stage IV. Walking distance was improved in 21% of patients, worsened in 73% of patients, and unchanged in 6% of patients. Stepwise multiple regression demonstrated that patients who started to walk or exercise (R = 0.372, P < 0.012) and who had a prior history of CABG (R = 0.467, P < 0.006) were the only independent predictors of the change in walking distance at follow-up. Those who started to walk reported worse walking distance at follow-up, while those with a history of CABG reported better walking distance at follow-up.

CONCLUSION

CABG prior to endovascular intervention is predictive of favorable change in walking distance in patients with PAD at follow-up. Therefore, post-CABG patients are good candidates for exercise rehabilitation and risk factor modification.

Port exteriorization appendectomy: is it the future?

The time honoured surgical procedure open appendectomy seems to be on the decline, it may be replaced in the modern era by laparoscopic appendectomy ("in appendectomy") performed with three trocars, or by the port exteriorization appendectomy ("out appendectomy") which can be done with two ports or even one. These techniques combine the benefits of decreased tissue trauma and operative time in addition to other advantages of minimal invasion. We conducted this study to know the effectiveness of Port Exteriorization Appendectomy, to analyze its complications and to assess the conversion rate. A one year prospective study consisted of fifty cases; a combination of emergency and elective group. They were operated under general anaesthesia and different variables were documented. Mean operative time, conversion rate, hospital stay, complications and patient satisfaction. There were 27 females with the (F: M) ratio of 1.17:1. The operative time of 23.3 mins, conversion in 4 (8.0%) patients and 2.4 days of hospital stay contributed to 86.0% operative success rate. Surgical site infection was seen in 5 (10.0%) patients and one (2.0%) developed pelvic abscess. On analysis of the satisfaction level, 44(93.6%) were completely satisfied and one (2.1%) patient seemed disappointed with the technique for cosmesis though, 42 (89.3%) remained completely satisfied and 5(10.7%) didn't like their scars. Port exteriorization appendectomy's efficacy can be verified by 86.0% success rate, operative time of 23.3 mins, indoor stay of 2.4 days, and minimal undesirable sequlae. However, more authentic results could be obtained if this technique is compared to open or laparoscopic appendectomy in a well designed randomized controlled clinical trial.

Factors influencing mortality in perforated duodenal ulcer following emergency surgical repair

Duodenal perforation is a common abdominal catastrophe with excellent outcome if prompt resuscitation and surgical repair of perforation are done. The aim of this study was to identify factors associated with death after surgery in patients with duodenal perforation. One hundred and forty-five patients who underwent Graham's patch repair for perforated duodenal ulcer between 14 April 2002 and 31 December 2004 were studied. The mean age was 45.99 years and 61 patients (42.07 %) were referrals. There were 124 (85.52 %) males and 21 (14.48 %) females. There were 10 deaths (6.9 %). The mean time delay was 2.46 days. It was 2.37 days in survivors, 3.7 days in non-survivors. The time delay was 3.25 days for females and 3.13 days for patients referred from another hospital. The mortality was significantly associated with time delay between perforation and operation (p<0.01), presence of co-morbid conditions (P<0.04), respiratory rate (p<0.02), raised blood urea (p<0.01) and serum creatinine (p<0.001), size of perforation (p<0.005), amount of peritoneal fluid (p=0.003) and requirement of postoperative intensive care unit support (p=0.003). Time delay between perforation and operation, preoperative blood urea and serum creatinine, size of perforation and amount of peritoneal fluid, presence of co-morbid conditions and need for post operative ICU support are the important predictors of outcome after emergency surgery for duodenal perforation.

Epidemiology and clinical pattern of hepatitis delta virus infection in Pakistan

BACKGROUND AND AIMS

The global epidemiology of hepatitis delta virus (HDV) infection is changing. This study was performed to determine the epidemiology and clinical impact of hepatitis delta in Pakistan.

METHODS

Countrywide data was collected from 1994 to 2001. A total of 8721 patients were tested for hepatitis delta antibody. A subset of 97 hepatitis delta antibody reactive inpatients with chronic liver disease were compared to 97 patients admitted with liver disease due to hepatitis B alone.

RESULTS

Of the 8721 patients tested, 1444 (16.6%) were reactive for hepatitis delta antibody. Most were males (87.4%, P < 0.001) and younger (mean age 31 years, P < 0.001) compared to HDV non-reactive patients. Prevalence of delta infection was highest in the rural (range 25-60%) compared to the urban population (range 6.5-11%). Analysis of the inpatient data showed that delta infected patients had significantly less severe clinical liver disease and a trend towards lesser development of hepatocellular carcinoma compared to delta negative patients.

CONCLUSIONS

(i) HDV infection is present in 16.6% of hepatitis B infected patients in Pakistan, most commonly in younger males living in rural areas; and (ii) delta virus infected patients have less severe clinical liver disease compared to delta negative, hepatitis B patients.