Normal width of the linea alba, prevalence, and risk factors for diastasis recti abdominis in adults, a cross-sectional study.

AIM: The prevalence and definition of diastasis recti abdominis (DRA) is under debate. This retrospective cross-sectional study evaluated the interrectal distance and the prevalence of DRA in computed tomography (CT) in an asymptomatic population. MATERIALS AND METHODS: Patients undergoing CT scans for suspected appendicitis or kidney stones from 01/2016 to 12/2018 were screened retrospectively to participate. A study population with equal distribution according to gender and age (18-90 years) was generated (n = 329 patients) and the interrectal distance was measured at six reference points. RESULTS: DRA (defined as > 2 cm at 3 cm above the umbilicus) was present in 57% of the population. The 80th percentile of the interrectal distance was 10 mm at the xiphoid (median 3 mm, 95% confidence interval (CI) 0-19 mm), 27 mm halfway from xiphoid to umbilicus (median 17 mm, 95% CI 0-39 mm), 34 mm at 3 cm above the umbilicus (median 22 mm, 95% CI 0-50 mm), 32 mm at the umbilicus (median 25 mm, 95% CI 0-45 mm), 25 mm at 2 cm below the umbilicus (median 14 mm, 95% CI 0-39 mm), and 4 mm halfway from umbilicus to pubic symphysis (median 0 mm, 95% CI 0-19 mm). In the multivariate analysis, higher age (p = 0.001), increased body mass index (p < 0.001), and parity (p < 0.037) were independent risk factors for DRA, while split xiphoid, tobacco abuse, and umbilical hernia were not. CONCLUSION: The prevalence of DRA is much higher than commonly estimated (57%). The IRD 3 cm above the umbilicus may be considered normal up to 34 mm. To avoid over-treatment, the definition of DRA should be revised.

Reduced and standard field-of-view diffusion weighted imaging in patients with rectal cancer at 3 T-Comparison of image quality and apparent diffusion coefficient measurements.

PURPOSE: To compare a zoomed EPI-DWI (z-EPI) with a standard EPI-DWI (s-EPI) in the primary diagnostics of rectal cancer and assess its potential of reduced image artifacts. METHOD: 22 therapy-naïve patients with rectal cancer underwent rectal MRI at a 3 T-system. The protocols consisted of a z-EPI DWI and s-EPI DWI sequence. Images were assessed by two independent and experienced readers regarding overall image quality and artifacts on a 5-point Likert scale, as well as overall sequence preference. In a lesion-based analysis, tumor and lymph node detection were rated on a 4-point Likert scale. Apparent diffusion coefficient (ADC) measurements were performed. RESULTS: Overall Image quality score for z-EPI and s-EPI showed no statistically significant differences (p = 0.80/0.54, reader 1/2) with a median score of 4 ("good" image quality) for both sequences. The image quality preference rank for z-EPI and s-EPI was given the category 'no preference' in 64 % (reader 1) and 50 % (reader 2). Most artifact-related scores (susceptibility, motion and distortion) did not show reproducible significant differences between z-EPI and s-EPI. The two sequences exhibited comparable, mostly good and excellent quality scores for tumor and lymph node detection (p = 0.19-0.99). ADC values were significantly lower for z-EPI than for s-EPI (p = 0.001/0.002, reader 1/2) with good agreement of ADC measurements between both readers. CONCLUSION: Our data showed comparable image quality and lesion detection for the z-EPI and the s-EPI sequence in MRI of rectal cancer, whereas the mean ADC of the tumor was significantly lower in z-EPI compared to s-EPI.

Enterothorax After Hepatic Surgery: A Single-Center Experience.

BACKGROUND: Enterothorax (ET) is a rare complication after hepatic surgery. The literature in this field is limited and mainly based on case reports. The aim of this study was to review our department's experience. PATIENTS AND METHODS: We retrospectively analyzed 602 patients who underwent hepatic resection between November 2008 and December 2016. Major hepatic surgery (n = 321) was defined as right or extended right hepatectomy (n = 227), left or extended left hepatectomy (n = 63), trisegmentectomy (n = 13), and living donor liver transplantation (n = 18). ET cases were identified by analyzing clinical courses and radiological imaging. RESULTS: ET was observed in five out of 602 patients (0.8%). All patients developed the complication after major hepatic surgery (five out of 321, 1.6%). ET exclusively occurred after right (n = 3) or extended right hepatectomy (n = 2). Median time to diagnosis was 22 months. Radiological imaging showed herniation of small (n = 2), large bowel (n = 2), or omental fat (n = 1) with a median diaphragmatic defect of 3.9 cm. Two patients presented with acute incarceration and underwent emergency surgery, one patient reported recurrent pain and underwent elective repair, and two patients refused surgery. Follow-up imaging in two operated patients showed no recurrence of ET after 36 and 8 months. CONCLUSIONS: Patients after right hepatectomy have a substantial risk of ET. Acute right upper quadrant pain and/or dyspnea after hepatectomy should be investigated with adequate radiological imaging. Elective surgical repair of ET is recommended to avoid emergency surgery in case of incarceration.

Short Chemotherapy-Free Interval Improves Oncological Outcome in Patients Undergoing Two-Stage Hepatectomy for Colorectal Liver Metastases.

BACKGROUND: In patients undergoing two-stage hepatectomy (TSH) for colorectal liver metastases (CRLM), chemotherapy is discontinued before portal vein occlusion and restarted after curative resection. Long chemotherapy-free intervals (CFI) may lead to tumor progression and poor oncological outcomes. OBJECTIVE: The aim of this study was to investigate the impact of the length of CFI on oncological outcome in patients undergoing TSH for CRLM. PATIENTS AND METHODS: Overall, 74 patients suffering from bilobar CRLM who underwent ALPPS (associating liver partition with portal vein ligation for staged hepatectomy; n = 43) or conventional TSH (n = 31) at two tertiary centers were investigated. The impact of CFI on long-term outcomes was analyzed by univariable and multivariable analysis. RESULTS: Preoperative chemotherapy was administered in 91 % (67/74) of patients, and chemotherapy was resumed postoperatively in 69 % (44/64) of patients who completed TSH. The use of postoperative chemotherapy was significantly associated with improved mean overall survival (36 ± 3 vs. 13 ± 3 months; p < 0.001). Overall, the median CFI from surgery to postoperative chemotherapy was 16 weeks (interquartile range 11-31) and was significantly shorter in the ALPPS group when compared with the conventional TSH group (10 vs. 21 weeks; p < 0.001). Multivariable analysis revealed a CFI ≤ 10 weeks as an independent factor associated with improved overall survival (p = 0.006) and disease-free survival (p = 0.010). CONCLUSION: A short CFI is associated with improved oncological outcome in patients undergoing TSH for CRLM. Decreased interstage intervals after ALPPS may facilitate the timely resumption of chemotherapy.

Model-based iterative reconstruction for improvement of low-contrast detectability in liver CT at reduced radiation dose: ex-vivo experience.

AIM: To compare low-contrast detectability, and qualitative and quantitative image parameters on standard and reduced radiation dose abdominal CT reconstructed with filtered back projection (FBP) and model-based iterative reconstruction (MBIR). MATERIALS AND METHODS: A custom built liver phantom containing 43 lesions was imaged at 120 kVp and four radiation dose levels (100% = 188 mAs, 50%, 25%, and 10%). Image noise and contrast-to-noise ratios (CNR) were assessed. Lesion detection and qualitative image analysis (five-point Likert scale with 1 = worst, 5 = best for confidence) was performed by three independent radiologists. RESULTS: CNR on MBIR images was significantly higher (mean 246%, range 151-383%) and image noise was significantly lower (69%, 59-78%) than on FBP images at the same radiation dose (both p < 0.05). On MBIR 10% images, CNR (3.3 ± 0.3) was significantly higher and noise (15 ± 1HU) significantly lower than on FBP 100% images (2.5 ± 0.1; 21 ± 1 HU). On 100% images, lesion attenuation was significantly lower with MBIR than with FBP (mean difference -2 HU). Low-contrast detectability and qualitative results were similar with MBIR 50% and FBP 100%. CONCLUSION: Low-contrast detectability with MBIR 50% and FBP 100% were equal. Quantitative parameters on even lower dose MBIR images are superior to 100%-dose FBP images. Some attenuation values differ significantly with MBIR compared with FBP.

Contrast-enhanced free-breathing 3D T1-weighted gradient-echo sequence for hepatobiliary MRI in patients with breath-holding difficulties.

OBJECTIVE: Evaluate the image quality and diagnostic performance of a free-breathing 3D-gradient-echo sequence with radial acquisition (rGRE) compared with a Cartesian breath-hold 3D-GRE (cGRE) sequence on hepatobiliary phase MRI in patients with breath-holding difficulties. METHODS: Twenty-eight consecutive patients (15 males; mean age 61 ± 11.9 years) were analysed in this retrospective IRB-approved study. Breath-holding difficulties during gadoxetate-disodium-enhanced liver MRI manifested as breathing artefacts during dynamic-phase imaging. MRI included axial and coronal cGRE and a radially sampled rGRE sequence during the hepatobiliary phase. Two radiologists independently evaluated cGRE and rGRE images for image quality, liver lesion detection and conspicuity, and bile duct conspicuity on a four-point scale. RESULTS: Liver edge sharpness was significantly higher on rGRE images (P < 0.001). Overall image quality was slightly but significantly higher for rGRE than for cGRE (P < 0.001 and P = 0.039). Bile duct conspicuity scores of rGRE and cGRE were not significantly different. Sensitivity for detection of the 26 liver lesions was similar for rGRE and cGRE (81-77 % and 73-77 %, P = 0.5 and 1.0). Lesion conspicuity scores were significantly higher for rGRE for one reader (P = 0.012). CONCLUSION: In patients with breath-holding difficulties, overall image quality and liver lesion conspicuity on hepatobiliary phase MRI can be improved using the rGRE sequence. KEY POINTS: • Patients with diminished breath-holding capacities present a major challenge in abdominal MRI. • A free-breathing sequence for hepatobiliary-phase MRI can improve image quality. • Further advances are needed to reduce acquisition time of the free-breathing gradient-echo sequence.

MR defecography in patients with dyssynergic defecation: spectrum of imaging findings and diagnostic value.

OBJECTIVES: We describe the spectrum of findings and the diagnostic value of MR defecography in patients referred with suspicion of dyssynergic defecation. METHODS: 48 patients (34 females, 14 males; mean age 48 years) with constipation and clinically suspected dyssynergic defecation underwent MR defecography. Patients were divided into patients with dyssynergic defecation (n = 18) and constipated patients without dyssynergic defecation (control group, n = 30). MRIs were analysed for evacuation ability, time to initiate evacuation, time of evacuation, changes in the anorectal angle (ARA-change), presence of paradoxical sphincter contraction and presence of additional pelvic floor abnormalities. Sensitivity, specificity, positive and negative predictive values and accuracy for the diagnosis of dyssynergic defecation were calculated. RESULTS: The most frequent finding was impaired evacuation, which was seen in 100% of patients with dyssynergic defecation and in 83% of the control group, yielding a sensitivity for MR defecography for the diagnosis of dyssynergic defecation of 100% (95% confidence interval (CI) 97-100%), but a specificity of only 23% (95% CI 7-40%). A lower sensitivity (50%; 95% CI 24-76%) and a high specificity (97%; 95% CI 89-100%) were seen with abnormal ARA-change. The sensitivity of paradoxical sphincter contraction was relatively high (83%; 95% CI 63-100%). A combined analysis of abnormal ARA-change and paradoxical sphincter contraction allowed for the detection of 94% (95% CI 81-100%) of the patients with dyssynergic defecation. CONCLUSION: MR defecography detects functional and structural abnormal findings in patients with clinically suspected dyssynergic defecation. Impaired evacuation is seen in patients with functional constipation owing to other pelvic floor abnormalities than dyssynergic defecation.

18F-FDG-PET and MRI in patients with malignancies of the liver and pancreas. Accuracy of retrospective multimodality image registration by using the CT-component of PET/CT.

PURPOSE: To evaluate the accuracy of retrospective rigid image registration and fusion between F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and magnetic resonance imaging (MRI) of the upper abdomen. PATIENTS, MATERIAL, METHODS: Image fusion of PET and MRI was performed in 30 patients with suspected malignancy of the liver or pancreas. Using a commercially available image fusion tool capable of rigid manual point-based registration, PET-Images were retrospectively registered and fused by matching eight homologous points in the 3D spoiled gradient echo (GRE) MRI sequences acquired in portal venous phase and in the CT-component of PET/CT. Two separate observers (R1, R2) assessed accuracy of image registration by determining the distances in the x-, y- and z-axis as well as the absolute distance between anatomical landmarks which differed from the landmarks chosen for registration. Quality of fusion was graded using a three point grading scale (1 poorly fused; 2 satisfactory fused; 3 correctly fused) and compared to hybrid PET/CT fusion. RESULTS: Mean time of registration per patient was less than 2 minutes. Objective registration assessment showed errors between 2.4-6.3 mm in x-axis: mean 3.6 mm (R1); 4.6 mm (R2), 2.3-9.3 mm in y-axis (mean 5.1 mm; 5.5 mm) and 3.3-12.0 mm in z-axis (mean 5.9 mm; 5.9 mm.) The mean error in absolute distance between points was 6.0-16.8 mm (mean 9.9 mm; 10.6 mm). In visual assessment, most fusions were graded to be satisfactory or correctly fused: R1, R2: grade 3, 11/30 (36.7%), 22/30 (73.3%); grade 2, 13/30 (43.3%), 8/30 (26.7%); grade 1, 6/30 (20%), 0/30 (0%). Fusions were mostly comparable to hybrid PET/CT fusions. All of the fusions were defined as diagnostically relevant by both observers. CONCLUSION: Retrospective rigid image fusion of FDG-PET and MRI of the upper abdomen using the CT-component of PET/CT for registration is feasible without adaptation in image acquisition protocols and shows sub-centimeter registration errors in most cases.

CT- and MRI-based volumetry of resected liver specimen: comparison to intraoperative volume and weight measurements and calculation of conversion factors.

OBJECTIVE: To compare virtual volume to intraoperative volume and weight measurements of resected liver specimen and calculate appropriate conversion factors to reach better correlation. METHODS: Preoperative (CT-group, n=30; MRI-group, n=30) and postoperative MRI (n=60) imaging was performed in 60 patients undergoing partial liver resection. Intraoperative volume and weight of the resected liver specimen was measured. Virtual volume measurements were performed by two readers (R1,R2) using dedicated software. Conversion factors were calculated. RESULTS: Mean intraoperative resection weight/volume: CT: 855 g/852 mL; MRI: 872 g/860 mL. Virtual resection volume: CT: 960 mL(R1), 982 mL(R2); MRI: 1112 mL(R1), 1115 mL(R2). Strong positive correlation for both readers between intraoperative and virtual measurements, mean of both readers: CT: R=0.88(volume), R=0.89(weight); MRI: R=0.95(volume), R=0.92(weight). Conversion factors: 0.85(CT), 0.78(MRI). CONCLUSION: CT- or MRI-based volumetry of resected liver specimen is accurate and recommended for preoperative planning. A conversion of the result is necessary to improve intraoperative and virtual measurement correlation. We found 0.85 for CT- and 0.78 for MRI-based volumetry the most appropriate conversion factors.

USPIO-enhanced magnetic resonance imaging of the knee in asymptomatic volunteers.

The aim of this study was to compare signal characteristics of the synovium in knees of asymptomatic volunteers before and after intravenous administration of ultrasmall superparamagnetic iron oxide particles (USPIO). Ten knees of 10 asymptomatic volunteers were examined before and 36 h after intravenous administration of USPIO on a 1.5-T MR system using T1-weighted spin-echo, T2-weighted fast spin-echo, T2*-weighted gradient-echo (GRE), and short inversion time inversion-recovery sequences. In addition, synovial perfusion was measured using Gd-enhanced GRE imaging during the first imaging session. Images were analyzed qualitatively for any visual changes before and after USPIO administration. Signal-to-noise ratios (SNR) of the synovium were determined on unenhanced and USPIO-enhanced sequences. All MR images were reviewed for presence of any degenerative changes. Qualitative image analysis revealed no visually detectable changes of any knee joint before and after USPIO administration. The SNR values of the synovium on T1w, T2w, and T2*w images before and after USPIO administration showed no significant difference (T1, P = 0.86; T2, P = 0.95; T2*, P = 0.86). None of the volunteers showed any relevant degenerative changes of the knee and synovial perfusion was within normal limits. In knees of asymptomatic volunteers without any relevant degenerative changes and normal synovial perfusion neither visual changes nor changes of SNR values of the synovium can be depicted after USPIO administration. This means that USPIO-enhanced MRI may be used for assessment of knee disorders with increased macrophage activity.

Mammography, sonography and MRI for detection and characterization of invasive lobular carcinoma of the breast.

Imaging of invasive lobular carcinoma (ILC) is more challenging than other types of breast cancer because of its spider web like growth pattern. Mammography has a relevant number of false negative exams, especially in dense breasts. Mammographic appearance of ILC is often subtle. Distinct mass like aspects are absent more often when compared with other types of breast cancer, and lesions are frequently only mildly opaque. Microcalcifications are uncommon. The addition of an ultrasound exam can improve rates of detection and diagnosis of ILC, but even when combining modalities ILC can be missed. If clinical signs are suspicious, magnetic resonance imaging (MRI) can help to detect ILC. MRI should also be considered in preoperative staging if treatment with breast conservation is favoured, particularly to assess maximal tumor dimensions. Mammographic findings do not correlate well with pathological tumor size. Additional tumor sites detected by MRI only should be validated cautiously, and guidelines established for multicentricity detected by mammography should not be used in the same way.