W. Schima

Clinical value of MRI liver-specific contrast agents: a tailored examination for a confident non-invasive diagnosis of focal liver lesions

Screening of the liver for hepatic lesion detection and characterization is usually performed with either ultrasound or CT. However, both techniques are suboptimal for liver lesion characterization and magnetic resonance (MR) imaging has emerged as the preferred radiological investigation. In addition to unenhanced MR imaging techniques, contrast-enhanced MR imaging can demonstrate tissue-specific physiological information, thereby facilitating liver lesion characterization. Currently, the classes of contrast agents available for MR imaging of the liver include non-tissue-specific extracellular gadolinium chelates and tissue-specific hepatobiliary or reticuloendothelial agents. In this review, we describe the MR features of the more common focal hepatic lesions, as well as appropriate imaging protocols. A special emphasis is placed on the clinical use of non-specific and liver-specific contrast agents for differentiation of focal liver lesions. This may aid in the accurate diagnostic workup of patients in order to avoid invasive procedures, such as biopsy, for lesion characterization. A diagnostic strategy that considers the clinical situation is also presented.

Anastomotic recurrence of Crohn’s disease after ileocolic resection: comparison of MR enteroclysis with endoscopy

The purpose of this study was to assess the accuracy of MR enteroclysis in patients with Crohn’s disease recurrence after ileocolic resection and to establish an MR scoring sytem. MR enteroclysis and endoscopy were performed in 30 patients with suspected Crohn’s disease recurrence after ileocolic resection. Findings were evaluated by three radiologists, using an MR score based on image quality, contrast enhancement, and mural and extramural bowel-wall changes: MR0 (no abnormal features), MR1 (minimal mucosal changes), MR2 (diffuse aphtoid ileitis, moderate recurrence), and MR3 (severe recurrence with trans- and extramural changes). The endoscopic Rutgeerts score defines changes at the ileum on a scale from I0 to I4. In 3/30 (10%) patients, evaluation was not possible. The mean overall image quality was rated as 1.7 (kappa 0.78). Comparing MR and Rutgeerts score, the mean observer agreement for the total score rating was 77.8% (kappa 0.67). When comparing only scores below or above MR2—the threshold indicative of the necessity of medical treatment—there was a total agreement of 95.1% (kappa 0.84). MR enteroclysis allows assessment of Crohn’s disease recurrence after ileocolic resection. The MR score is reproducible and shows high agreement with the approved endoscopic Rutgeerts score.

Endoscopy and MR enteroclysis: Equivalent tools in predicting clinical recurrence in patients with Crohn's disease after ileocolic resection

Background: Ileocolonoscopy poses the gold standard in the evaluation of postoperative recurrence of Crohns disease (CD) at the site of ileocolonic anastomosis. Magnetic resonance enteroclysis (MRE) on the other hand is a promising technique for small bowel imaging. The aim was to compare MRE and ileocolonoscopy for predicting clinical recurrence in CD patients who have undergone ileocolonic resection. Methods: We included 29 patients in the study. The median time since index operation was 35 months and between ileocolonoscopy and MRE was 3 days. Patients were followed up for a maximum of 2 years unless clinical recurrence occurred earlier. Endoscopic findings were evaluated on a 5‐grade scale (i0–i4), whereas MRE findings on the neoterminal ileum and anastomosis were assessed according to a previously validated 4‐grade scale MR score (MR0‐MR3). Results: By classifying patients into subgroups of endoscopic severity of postoperative recurrence using as a threshold an endoscopic score of i3, we found that 10% of patients in the i0 to i2 group had a clinical recurrence during the 2‐year follow‐up period as compared to 52.6% of subjects with i3 to i4 (P = 0.043). The corresponding clinical exacerbation rates in the subgroups based on MRE severity assessment were 12.5% for MR0 to MR1 and 50% for MR2 to MR3 (P = 0.09). Conclusions: Our data suggest that colonoscopy and MR enteroclysis are of similar value to predict the risk of clinical recurrence in postoperative patients with Crohns disease. Inflamm Bowel Dis 2009

Size of surgical margin does not influence recurrence rates after curative liver resection for colorectal cancer liver metastases.

The aim of this study was to examine the relationship between surgical margin status and site of recurrence after potentially curative liver resection for colorectal metastases using an ultrasonic dissection technique.

Artifacts in body MR imaging: their appearance and how to eliminate them

A wide variety of artifacts can be seen in clinical MR imaging. This review describes the most important and most prevalent of them, including magnetic susceptibility artifacts and motion artifacts, aliasing, chemical-shift, zipper, zebra, central point, and truncation artifacts. Although the elimination of some artifacts may require a service engineer, the radiologist and MR technologist have the responsibility to recognize MR imaging problems. This review shows the typical MR appearance of the described artifacts, explains their physical basis, and shows the way to solve them in daily practice.

Effect of computer-aided detection as a second reader in multidetector-row CT colonography

Our purpose was to assess the effect of computer-aided detection (CAD) on lesion detection as a second reader in computed tomographic colonography, and to compare the influence of CAD on the performance of readers with different levels of expertise. Fifty-two CT colonography patient data-sets (37 patients: 55 endoscopically confirmed polyps ≥0.5xa0cm, seven cancers; 15 patients: no abnormalities) were retrospectively reviewed by four radiologists (two expert, two nonexpert). After primary data evaluation, a second reading augmented with findings of CAD (polyp-enhanced view, Siemens) was performed. Sensitivities and reading time were calculated for each reader without CAD and supported by CAD findings. The sensitivity of expert readers was 91% each, and of nonexpert readers, 76% and 75%, respectively, for polyp detection. CAD increased the sensitivity of expert readers to 96% (Pu2009=u20090.25) and 93% (Pu2009=u20091), and that of nonexpert readers to 91% (Pu2009=u20090.008) and 95% (Pu2009=u20090.001), respectively. All four readers diagnosed 100% of cancers, but CAD alone only 43%. CAD increased reading time by 2.1xa0min (mean). CAD as a second reader significantly improves sensitivity for polyp detection in a high disease prevalence population for nonexpert readers. CAD causes a modest increase in reading time. CAD is of limited value in the detection of cancer.

Preoperative evaluation of colorectal liver metastases: comparison between gadoxetic acid-enhanced 3.0-T MRI and contrast-enhanced MDCT with histopathological correlation

AbstractObjectivesThe aim of this prospective study was to compare the diagnostic performance of 64-row MDCT and gadoxetic-acid-enhanced MRI at 3.0 T in patients with colorectal liver metastases in correlation with histopathological findings.MethodsLesions detected at MDCT and MRI were interpreted by three blinded readers and compared with histopathological workup as the term of reference. Two subgroups of lesions were additionally evaluated: (1) metastases smaller than 10xa0mm and (2) lesions in patients with and without steatosis of the liver, assessed histopathologically.ResultsSurgery and histopathological workup revealed 81 colorectal liver metastases in 35 patients and diffuse metastatic involvement in 3 patients. In a lesion-by-lesion analysis, significant sensitivity differences could only be found for reader 1 (Pu2009=u20090.035) and reader 3 (Pu2009=u20090.003). For segment-based evaluation, MRI was more sensitive only for reader 3 (Pu2009=u20090.012). The number of false-positive results ranged from 3 to 12 for MDCT and 8 to 11 for MRI evaluation. In the group of small lesions, the sensitivity differed significantly between both methods (Pu2009=u20090.003). In patients with hepatic steatosis, MRI showed a trend toward better performance than MDCT, but without statistical performance.ConclusionsThe 3.0-T MRI with liver-specific contrast agents is the preferred investigation in the preoperative setting, especially for the assessment of small colorectal liver metastases.Key Points• Potential surgical treatment requires accurate radiological assessment of colorectal liver metastasesn • Magnetic resonance imaging with gadoxetic acid is the preferred imaging investigation.n • MRI is better than multidetector CT for detecting small liver metastases.

Detection of histologically proven peritoneal carcinomatosis with fused 18F-FDG-PET/MDCT

OBJECTIVEnTo evaluate peritoneal carcinomatosis in patients with gastrointestinal and gynecologic malignancies and to assess the diagnostic role for 18-FDG-PET and MDCT alone in comparison to the diagnostic accuracy of fused 18F-FDG-PET/MDCT by using surgical and histopathological findings as the standard of reference.nnnMETHODS AND SUBJECTSnSixty-two patients (13 males, 49 females; age range 43-81; mean age, 62 years with suspected peritoneal carcinomatosis were reviewed for the presence of peritoneal lesions on 18F-FDG-PET/MDCT scans (Discovery LS, GE Medical Systems). The results were compared with the histological findings at laparatomy. Thirty-one patients had peritoneal metastases, while 31 patients had negative histological findings at laparotomy.nnnRESULTSnCT detected peritoneal seeding in 26/31 patients, 18F-FDG-PET in 25/31 patients, and 18F-FDG-PET/MDCT in 30/31 patients, for a sensitivity of 88%, 88%, and 100%, respectively. False-positive findings were seen in MDCT in one patient, in 18F-FDG-PET in two patients, and in 18F-MDCT-PET/MDCT in one patient, for a specificity of 97%, 94%, and 97%, respectively.nnnCONCLUSIONnFused 18F-FDG-PET/MDCT is superior to MDCT and 18F-FDG-PET alone for the detection of peritoneal carcinomatosis especially in small lesions and it offers exact anatomic information for surgical treatment.

Gadoxetic acid-enhanced 3.0 T MR imaging versus multidetector-row CT in the detection of colorectal metastases in fatty liver using intraoperative ultrasound and histopathology as a standard of reference.

OBJECTIVEnTo compare the diagnostic value of gadoxetic acid-enhanced MRI at 3.0 T with 64-row MDCT in the detection of colorectal liver metastases in diffuse fatty infiltration of the liver after neoadjuvant chemotherapy.nnnMETHODSnTwenty-three patients with colorectal liver metastases and at moderate to severe steatosis (25-90%) underwent prospectively preoperative tri-phasic MDCT (Somatom Sensation 64, Siemens) and gadoxetic acid-enhanced MRI (3-T Magnetom Trio, Siemens). All patients underwent surgical resection of liver metastases. Intraoperative ultrasound (IOUS) was carried out, which served as the standard of reference, together with histopathology.nnnRESULTSnOverall, 68 metastases (range, 0.4-6 cm; 31/68 metastases [46%] ≤ 1 cm) were found at histology. MDCT detected 49/68 lesions (72%), and MRI 66/68 (97%, p < 0.001). For lesions ≤ 1 cm, MDCT detected only 13/31 (41.9%) and MRI 29/31 (93%, p < 0.001). Eight false-positive lesions were detected by MDCT, seven small lesions by MRI. There was no statistically significant difference between the two modalities in the detection of lesions > 1 cm (p = 0.250). IOUS detected all metastases and revealed two false-positive diagnoses.nnnCONCLUSIONnGadoxetic acid-enhanced 3.0 T MRI is superior to 64-row MDCT in detecting colorectal liver metastases ≤ 1 cm during preoperative staging in patients with liver steatosis. A combination of MRI and IOUS may further improve the outcome of surgical treatment.

Post-treatment imaging of liver tumours.

Abstract In the past few years, great improvements have been made to achieve local tumour control of primary liver malignancies and liver metastases. For hepatocellular carcinoma (HCC), transarterial chemoembolisation (TACE) and tumour ablation techniques, including percutaneous ethanol injection (PEI), radiofrequency ablation (RF), and laser-induced interstitial thermotherapy (LITT) have been developed. For colorectal liver metastases, surgery is still the standard technique in localised disease, although percutaneous RF ablation has gained considerable acceptance. In patients with widespread disease, chemotherapy with new drugs offers improved survival. Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) are the modalities of choice to evaluate treatment response. The present review demonstrates imaging findings of complete and incomplete tumour control after intervention as well as the imaging spectrum of complications. Imaging guidelines according to the World Health Organization and Response Evaluation Criteria In Solid Tumors (RECIST) for assessment of chemotherapy response are presented.