Low-dose CT for diagnosing intestinal obstruction and pneumoperitoneum; need for retakes and diagnostic accuracy.

BACKGROUND: One of the main concerns using low-dose (LD) CT for evaluation of patients with suspected intestinal obstruction or pneumoperitoneum is the potential need to make an additional standard-dose (SD) CT scan (retake) due to insufficient diagnostic accuracy of the LD CT. PURPOSE: To determine the frequency of retakes and evaluate the diagnostic accuracy of LD CT for the assessment of intestinal obstruction and pneumoperitoneum. MATERIAL AND METHODS: This retrospective study registered all LD CT scans over a one-year period at Aarhus University Hospital, Denmark in patients with suspected intestinal obstruction or perforation, comprising a total of 643 LD CT scans. A retake was defined as a SD CT scan of the abdomen and pelvis performed with or without intravenous contrast within 72 h after the initial LD CT due to either continued suspicion of intestinal obstruction or perforation or due to unclarified secondary findings. The sensitivity and specificity of LD CT for diagnosing intestinal obstruction and pneumoperitoneum compared to the discharge diagnoses of the scanned patients were determined. RESULTS: The frequency of retakes was 3%. The overall LD CT sensitivity and specificity for assessment of patients with suspected intestinal obstruction and pneumoperitoneum was 83% and 99%, respectively, but higher in certain subgroups. CONCLUSIONS: LD CT led to few retakes and had a high diagnostic accuracy for diagnosing intestinal obstruction and pneumoperitoneum. Thus, LD CT can be recommended as the examination of choice in patients with suspected intestinal obstruction or perforation in order to reduce radiation dose.

ß-Blockers Improve Presinusoidal Portal Hypertension.

BACKGROUND: Presinusoidal portal hypertension is a clinically important cause of gastric and gastroesophageal varices. Whereas ß-blockers have an established prophylactic role against bleeding from esophageal and gastric varices in portal hypertension due to cirrhosis, the effect on presinusoidal portal hypertension is unknown. AIMS: To evaluate the hemodynamic effect of ß-blockers in non-cirrhotic patients with presinusoidal portal hypertension. METHODS: We measured the blood pressure gradient from spleen pulp to free hepatic vein in 12 patients with presinusoidal portal hypertension by combined hepatic vein catheterization and spleen pulp puncture while on and off ß-blocker treatment (random sequence). RESULTS: The ß-blockers reduced the gradient from a mean off-treatment value of 32 mm Hg to a on-treatment value of 26 mm Hg (P < 0.05) with a reduction of at least 20% in five patients (42%). CONCLUSIONS: ß-blocker treatment caused a clinically significant reduction in the pressure gradient from spleen pulp to the free hepatic vein. This finding supports the recommendation for prophylactic ß-blockage in patients with presinusoidal portal hypertension.

Diagnostic accuracy of CE-CT, MRI and FDG PET/CT for detecting colorectal cancer liver metastases in patients considered eligible for hepatic resection and/or local ablation.

PURPOSE: To compare the diagnostic performance of contrast-enhanced computed tomography (CE-CT), magnetic resonance imaging (MRI) and combined fluorodeoxyglucose/positron emission tomography/computed tomography (FDG-PET/CT) for detection of colorectal liver metastases (CRLM) in patients eligible for local treatment. MATERIALS AND METHODS: This health-research ethics-committee-approved prospective consecutive diagnostic accuracy study, with written informed consent, included 80 cases (76 patients, four participating twice) between 29 June 2015 and 7 February 2017. Prior chemotherapy or local treatment did not exclude participation. Combined FDG-PET/CT including CE-CT and MRI was performed within 0-3 days shortly before local treatment. CE-CT and MRI images were read independently by two readers for each modality. The combined FDG-PET/CT images were read independently by two pairs of readers. A composite reference standard was used. Sensitivities, specificities and area under the receiver operating characteristic curves (AUCROC) were calculated and compared. RESULTS: In total, 260 CRLMs were confirmed. The MRI readers had significantly higher per-lesion sensitivity (85.9% and 83.8%) than both CE-CT readers (69.1% and 62.3%) and both PET/CT reader pairs (72.0% and 72.1%) (p<0.001). There were no significant differences in per-lesion specificity. MRI readers had significantly higher AUCROC (0.92 and 0.88) than both CE-CT readers (0.80 and 0.82) (p≤0.001). AUCROC for MR reader 1 was higher than that of both PET/CT reader pairs (0.83 and 0.84) (p≤0.0001). CONCLUSION: MRI performed significantly better than both CE-CT and combined FDG-PET/CT for detection of CRLM in consecutive patients eligible for local treatment irrespective of prior chemotherapy or local treatment. KEY POINTS: • Patients eligible for local treatment of colorectal liver-metastases require optimal imaging. • In 80 consecutive patients, MRI had superior per lesion diagnostic performance. • Findings were independent of prior treatment and type of planned local treatment. • Equally, MRI had superior diagnostic performance on per segment basis.

A Prospective Cohort Study of Gated Stereotactic Liver Radiation Therapy Using Continuous Internal Electromagnetic Motion Monitoring.

PURPOSE: Intrafraction motion can compromise the treatment accuracy in liver stereotactic body radiation therapy (SBRT). Respiratory gating can improve treatment delivery; however, gating based on external motion surrogates is inaccurate. The present study reports the use of Calypso-based internal electromagnetic motion monitoring for gated liver SBRT. METHODS AND MATERIALS: Fifteen patients were included in a study of 3-fraction respiratory gated liver SBRT guided by 3 implanted electromagnetic transponders. The planning target volume was created by a 5-mm axial and 7-mm (n = 12) or 10-mm (n = 3) craniocaudal expansion of the clinical target volume (CTV) and covered with 67% of the prescribed CTV mean dose. Treatment was gated to the end-exhale phase of the respiratory cycle with beam-on when the target deviated <3 mm (left-right/anteroposterior) and 4 mm (craniocaudal) from the planned position, according to the monitored (25-Hz) transponder centroid position. The couch was adjusted remotely if baseline drifts >1 to 2 mm occurred. Log files of transponder motion were used to determine the geometric error and reconstruct the delivered CTV dose in the actual gated treatments and in simulated nongated treatments. RESULTS: No severe side effects were observed in relation to transponder implantation. All 45 treatment fractions were successfully guided using the Calypso system. The mean number of couch corrections during each gated fraction was 2.8 (range 0-7). The mean duty cycle during gated treatment was 62.5% (range 29.1%-84.9%). Without gating, the mean 3-dimensional geometric error during a fraction would have been 5.4 mm (range 2.7-12.1). Gating reduced this error to 2.0 mm (range 1.2-3.0). The patient mean reduction in minimum dose to 95% of the CTV relative to the planned dose was 6.0 percentage points (range 0.7-22.0) without gating and 0.8 percentage point (range 0.2-2.0) with gating. CONCLUSIONS: Gating using internal motion monitoring was successfully applied for liver SBRT. It markedly improved the geometric and dosimetric accuracy compared with nongated standard treatment.

Comparison of four MRI protocols for detection of extrahepatic colorectal cancer metastases.

PURPOSE: To compare three magnetic resonance imaging (MRI) protocols containing diffusion-weighted imaging with background suppression (DWIBS) and one traditional protocol for detecting extrahepatic colorectal cancer metastases. MATERIALS AND METHODS: Thirty patients with extrahepatic colorectal cancer metastases were scanned in three stations from the skull base to the upper thighs using a 1.5T MRI system with six different MRI sequences; transverse and coronal T2 -weighted (T2 W) turbo spin-echo (TSE), coronal short tau inversion recovery (STIR), 3D T1 W TSE, DWIBS, and a contrast-enhanced T1 W 3D gradient echo (GRE) sequence. The six sequences were used to build four hypothetical MRI interpretive sets which were read by two readers in consensus, blinded to prior imaging. Lesions were categorized into 13 anatomic regions. Fluorodeoxyglucose / positron emission tomography / computed tomography (FDG-PET/CT) read with full access to prior imaging and clinical records was used as the reference standard. Sensitivity, specificity, and false discovery rate (FDR) were calculated as appropriate and receiver operating characteristic (ROC) curves were constructed. RESULTS: In all, 177 malignant lesions were detected by FDG-PET/CT and distributed in 92 out of 390 scanned anatomic regions. The sensitivity was statistically higher in two out of three sets incorporating DWIBS on a per-lesion basis (66.7%, 63.3%, and 66.7% vs. 57.6%) (P = 0.01, P = 0.11, and P = 0.01, respectively) and in all sets incorporating DWIBS on a per-region basis (75.0%, 75.0%, and 77.2 vs. 66.3%) (P = 0.04, P = 0.04, and P = 0.01, respectively). There was no difference in specificity, FDR, or AUCROC . There was no difference between sets containing DWIBS irrespective of the use of a contrast-enhanced sequence. CONCLUSION: MRI sets containing DWIBS had superior sensitivity. This sensitivity was retained when omitting a contrast-enhanced sequence. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1619-1630.

Fiducial marker guided stereotactic liver radiotherapy: Is a time delay between marker implantation and planning CT needed?

To minimize the risk of marker migration in fiducial marker guided liver SBRT it is common to add a delay of a week between marker implantation and planning CT. This study found that such a delay is unnecessary and could be avoided to minimize the treatment preparation time.

Black or white coffee before anaesthesia?: A randomised crossover trial.

BACKGROUND: In current preoperative fasting guidelines, coffee with milk is still regarded by many as solid food. Evidence on the consequences for gastric volume of adding milk to coffee 2 h before anaesthesia is still weak. OBJECTIVES: The aim of this study was to compare the gastric volume by MRI in healthy volunteers after drinking coffee with and without added milk. DESIGN: A randomised crossover trial where all participants were exposed to three coffee and milk mixtures performed as a noninferiority study with a predefined noninferiority limit of 12 ml. SETTING: Department of Day Surgery and Department of Radiology, Aarhus University Hospital, Aarhus, Denmark. The study was conducted between August 2013 and February 2014. PARTICIPANTS: Total 32 healthy volunteers, aged 18 to 71 years. INTERVENTIONS: The participants fasted for 6 h for solid food, and 2 h before the MRI examination of gastric volume, each participant ingested one of three coffee mixtures: 175 ml coffee, including either 0 or 20 or 50% full fat milk. Each participant was studied by MRI three times separated by a minimum time interval of 2 days. The order of coffee mixture ingested was determined by random allocation. MAIN OUTCOME MEASURE: Gastric volume as measured by MRI. RESULTS: The mean gastric volume for black coffee was 27.8 ml, for coffee with 20% milk 17.9 ml and for coffee with 50% milk 20.6 ml. Compared to black coffee, the gastric volume for 20% milk was significantly decreased with a difference of -10.0 ml (95% confidence interval, -18.2, -1.8), and for 50% milk it was insignificantly decreased, -7.2 ml (95% confidence interval, -17.4, +2.9). The upper confidence interval for the difference in gastric volume between the 'no milk added' group and each 'milk added' group did not reach the noninferiority limit of 12 ml. CONCLUSION: The study provides evidence that adding up to 50% full fat milk to coffee leads to no or only a minimal increase of the gastric volume 2 h later. The results support a liberalisation of policy on the addition of milk to hot drinks before planned anaesthesia. TRIAL REGISTRATION: www.Clinicaltrials.gov identifier: NCT02361632.

Percutaneous cholecystostomy is an effective treatment option for acute calculous cholecystitis: a 10-year experience.

BACKGROUND: Percutaneous cholecystostomy (PC) can be used to treat patients with acute calculous cholecystitis (ACC) who are considered to be unfit for surgery. However, this procedure has been insufficiently investigated. This paper presents the results of a 10-year experience with this treatment modality. METHODS: A retrospective observational study of all consecutive patients treated with PC for ACC in the period from 1 May 2002 to 30 April 2012 was conducted. All data were collected from patients' medical records. RESULTS: A total of 278 patients were treated with PC for ACC. Of these, 13 (4.7%) died within 30 days, 28 (10.1%) underwent early laparoscopic cholecystectomy and three (1.1%) patients were lost from follow-up. Of the remaining 234 patients, 55 (23.5%) were readmitted for the recurrence of cholecystitis. In 128 (54.7%) patients, PC was the definitive treatment (median follow-up time: 5 years), whereas 51 (21.8%) patients were treated with elective laparoscopic cholecystectomy. The frequency of recurrence of cholecystitis in patients with contrast passage to the duodenum on cholangiography was lower than that in patients without contrast passage (21.1% versus 36.7%; P = 0.037). CONCLUSIONS: The present study, which is the largest ever conducted in this treatment area, supports the hypothesis that PC is an effective treatment modality for critically ill patients with ACC unfit for surgery and results in a low rate of 30-day mortality.

On-line use of three-dimensional marker trajectory estimation from cone-beam computed tomography projections for precise setup in radiotherapy for targets with respiratory motion.

PURPOSE: To develop and evaluate accurate and objective on-line patient setup based on a novel semiautomatic technique in which three-dimensional marker trajectories were estimated from two-dimensional cone-beam computed tomography (CBCT) projections. METHODS AND MATERIALS: Seven treatment courses of stereotactic body radiotherapy for liver tumors were delivered in 21 fractions in total to 6 patients by a linear accelerator. Each patient had two to three gold markers implanted close to the tumors. Before treatment, a CBCT scan with approximately 675 two-dimensional projections was acquired during a full gantry rotation. The marker positions were segmented in each projection. From this, the three-dimensional marker trajectories were estimated using a probability based method. The required couch shifts for patient setup were calculated from the mean marker positions along the trajectories. A motion phantom moving with known tumor trajectories was used to examine the accuracy of the method. Trajectory-based setup was retrospectively used off-line for the first five treatment courses (15 fractions) and on-line for the last two treatment courses (6 fractions). Automatic marker segmentation was compared with manual segmentation. The trajectory-based setup was compared with setup based on conventional CBCT guidance on the markers (first 15 fractions). RESULTS: Phantom measurements showed that trajectory-based estimation of the mean marker position was accurate within 0.3 mm. The on-line trajectory-based patient setup was performed within approximately 5 minutes. The automatic marker segmentation agreed with manual segmentation within 0.36 ± 0.50 pixels (mean ± SD; pixel size, 0.26 mm in isocenter). The accuracy of conventional volumetric CBCT guidance was compromised by motion smearing (≤21 mm) that induced an absolute three-dimensional setup error of 1.6 ± 0.9 mm (maximum, 3.2) relative to trajectory-based setup. CONCLUSIONS: The first on-line clinical use of trajectory estimation from CBCT projections for precise setup in stereotactic body radiotherapy was demonstrated. Uncertainty in the conventional CBCT-based setup procedure was eliminated with the new method.