Rectal tumour volume (GTV) delineation using T2-weighted and diffusion-weighted MRI: Implications for radiotherapy planning.

PURPOSE: To compare the rectal tumour gross target volume (GTV) delineated on T2 weighted (T2W MRI) and diffusion weighted MRI (DWI) images by two different observers and to assess if agreement is improved by DWI. MATERIAL AND METHODS: 27 consecutive patients (15 male, range 27.1-88.8 years, mean 66.9 years) underwent 1.5T MRI prior to chemoradiation (45Gy in 25 fractions; oral capecitabine 850mg/m(2)), including axial T2W MRI (TR=6600ms, TE=90ms) and DWI (TR=3000ms, TE=77ms, b=0, 100, 800s/mm(2)). 3D tumour volume (cm(3)) was measured by volume of interest (VOI) analysis by two independent readers for the T2W MRI and b800 DWI axial images, and the T2W MRI and DWI volumes compared using Mann-Whitney test. Observer agreement was assessed using Bland-Altman statistics. Significance was at 5%. RESULTS: Artefacts precluded DWI analysis in 1 patient. In the remaining 26 patients evaluated, median (range) T2W MRI MRI and DWI (b=800s/mm(2)) 3D GTVin cm(3) were 33.97 (4.44-199.8) and 31.38 (2.43-228), respectively, for Reader One and 43.78 (7.57-267.7) and 42.45 (3.68-251) for Reader Two. T2W MRI GTVs were slightly larger but not statistically different from DWI volumes: p=0.52 Reader One; p=0.92 Reader Two. Interobserver mean difference (95% limits of agreement) for T2W MRI and DWI GTVs were -9.84 (-54.96 to +35.28) cm(3) and -14.79 (-54.01 to +24.43) cm(3) respectively. CONCLUSION: Smaller DWI volumes may result from better tumour conspicuity but overall observer agreement is not improved by DWI.

MRI of anal cancer: assessing response to definitive chemoradiotherapy.

Anal cancer is an uncommon malignancy of the gastrointestinal tract but has a relatively good prognosis with an 80% 5-year overall survival. In this article, we review the role of MRI for assessing treatment response in anal cancer after completion of definitive chemoradiotherapy. New generation MRI scanners with optimal-phased array body coils, resulting in better signal to noise and improved contrast and spatial resolution, have contributed to high-resolution imaging in clinical practice enabling visualization of relevant anatomy including the sphincter complex, adjacent structures, mesorectal and pelvic lymph nodes with a diameter down to 2 mm. Multiplanar, high-resolution T2-weighted and diffusion-weighted sequences have a role in initial locoregional staging of anal SCC, assisting radiotherapy planning, as well as in assessing response to treatment and treatment-related complications.

Reproducibility and clinical correlations of post-treatment changes on CT of prostate cancer bone metastases treated with chemotherapy.

OBJECTIVES: The objective of this study was to determine whether, in patients with prostate cancer (PCa) bone metastases receiving chemotherapy, early post-treatment changes on CT are reproducible and associated with clinical outcomes. METHODS: Blinded to outcomes, two radiologists with 1 year and 5 years of experience independently reviewed CTs obtained before and 3 months after chemotherapy initiation in 38 patients with bone metastases from castration-resistant PCa, recording the size, matrix and attenuation of ≤5 lesions; presence of new lesions, extraosseous components, periosteal reactions and cortical thickening; and overall CT assessment (improved, no change or worse). Kappa statistics were used to assess inter-reader agreement; the Kruskal-Wallis test and Cox regression model were used to evaluate associations. RESULTS: Inter-reader agreement was low/fair for size change (concordance correlation coefficient=0.013), overall assessment and extraosseous involvement (κ=0.3), moderate for periosteal reaction and cortical thickening (κ=0.4-0.5), and substantial for CT attenuation (κ=0.7). Most metastases were blastic (Reader 1, 58%; Reader 2, 67%) or mixed lytic-blastic (Reader 1, 42%; Reader 2, 34%). No individual CT features correlated with survival. Readers 1 and 2 called the disease improved in 26% and 5% of patients, unchanged in 11% and 21%, and worse in 63% and 74%, respectively, with 64% interreader agreement. Overall CT assessment did not correlate with percentage change in prostate-specific antigen level. For the more experienced reader (Reader 2), patients with improved or unchanged disease had significantly longer median survival (p=0.036). CONCLUSIONS: In PCa bone metastases, interreader agreement is low in overall CT post-treatment assessment and varies widely for individual CT features. Improved or stable disease identified by an experienced reader is statistically associated with longer survival.

Standardisation of liver MDCT by tracking liver parenchyma enhancement to trigger imaging.

OBJECTIVE: To assess parenchymal bolus-triggering in terms of liver enhancement, lesion-to-liver conspicuity and inter-image variability across serial follow-up MDCTs. METHODS: We reviewed MDCTs of 50 patients with hepatic metastases who had a baseline CT and two follow-up examinations. In 25 consecutive patients CT data acquisition was initiated by liver parenchyma triggering at a 50-HU enhancement threshold. In a matched control group, imaging was performed with an empirical delay of 65 s. CT attenuation values were assessed in vessels, liver parenchyma and metastasis. Target lesions were classified according to five enhancement patterns. RESULTS: Compared with the control group, liver enhancement was significantly higher with parenchyma triggering (59.8 ± 7.6 HU vs. 48.8 ± 11.2 HU, P = 0.0002). The same was true for conspicuity (liver parenchyma - lesion attenuation) of hypo-enhancing lesions (72.2 ± 15.9 HU vs. 52.7 ± 19.4 HU, P = 0.0006). Liver triggering was associated with reduced variability for liver enhancement among different patients (P = 0.035) and across serial follow-up examinations in individual patients (P < 0.0001). The number of patients presenting with uniform lesion enhancement pattern across serial examinations was significantly higher in the triggered group (20 vs. 11; P = 0.018). CONCLUSION: Liver parenchyma triggering provides superior lesion conspicuity and improves standardisation of image quality across follow-up examinations with greater uniformity of enhancement patterns. KEY POINTS: Liver parenchyma tracking improves liver enhancement and lesion-to-liver conspicuity in abdominal CT. In serial CT studies this technique reduces variability of conspicuity and enhancement patterns. Higher liver-to-lesion conspicuity is a prerequisite for reliable detection of liver lesions. Stabilisation of enhancement permits more accurate follow-up of oncology patients.

MRI at the completion of chemoradiotherapy can accurately evaluate the extent of disease in women with advanced urethral carcinoma undergoing anterior pelvic exenteration.

AIM: To demonstrate the value of pelvic magnetic resonance imaging (MRI) in mapping tumour extension after chemoradiotherapy and before anterior pelvic exenteration in patients with primary carcinoma of the urethra. MATERIALS AND METHODS: The Institutional Review Board approved and issued a waiver of informed consent for this retrospective study, which was compliant with the Health Insurance Portability and Accountability Act. Six women (median age 51 years, range 39-63 years) with histopathology-proven urethral carcinoma who underwent neoadjuvant chemoradiotherapy before anterior pelvic exenteration were included in the study. All had MRI performed at first presentation and after completion of chemoradiotherapy. MRI images were analysed by an experienced reader, who was blinded to the clinical data. The tumour location, signal intensity, size, local extension, and presence of enlarged lymph nodes were recorded for each patient at baseline and after chemoradiotherapy. Surgical histopathology constituted the reference standard. RESULTS: All tumours were locally advanced (stage T3) at baseline MRI. The mean maximum diameter of the tumour at baseline MRI was 3.7 cm (range 2.4-5 cm). After chemoradiotherapy, the mean reduction in maximum tumour diameter on MRI was 44% (range 13-67%), but only three cases were down-staged. MRI was accurate in the evaluation of tumour extension after completion of chemoradiotherapy in all cases. Persistence of bladder neck and anterior vaginal wall invasion was correctly identified in three cases. CONCLUSION: In women with advanced primary urethral cancer, MRI is an excellent tool for monitoring neo-adjuvant chemoradiotherapy changes and evaluating the extent of disease before exenterative surgery.

Air trapping in Wegener's granulomatosis: an additional finding on expiratory chest HRCT.

PURPOSE: This study was undertaken to assess the presence and extent of air trapping (AT) on high-resolution computed tomography (HRCT) in patients with Wegener's granulomatosis (WG) and to correlate the finding with the inspiratory pattern and bronchial/bronchiolar involvement. MATERIALS AND METHODS: Twenty-one patients (7 M/14 F) with WG underwent inspiratory and expiratory HRCT. Images were evaluated for the presence and extent of AT and for airway involvement (bronchi/bronchioles); the predominant HRCT pattern was also documented. The attenuation difference was measured between the areas of AT on expiration and the same areas on inspiration in order to verify the finding of AT. The extent of AT was calculated by visual scoring and correlated with the predominant inspiratory patterns and bronchial/bronchiolar involvement. RESULTS: AT was found in seven patients (33.3%) and its extent ranged between 3% and 70% (mean 15.8±7). Two patients showed no lesions on inspiratory HRCT, and the only finding was AT on expiration. The attenuation difference between areas of AT on expiration and the same areas on inspiration ranged between 32 and 89 HU. Inspiratory HRCT was pathological in 19 patients (90.4%), and the principal lung patterns were nodular, cavitary or noncavitary (n=7, 38.9%); ground-glass opacities (n=5, 26.3%); masses (n=3, 15.8%); fibrotic (n=3, 15.8%); and consolidation with air bronchogram (n=1, 5.3%). Bronchial and bronchiolar involvement was found in 14 and five patients, respectively. No statistically significant correlation was found between AT extent and the findings on inspiration. In addition, there were no specific patterns that caused higher or lower scores of AT. Moreover, when bronchial or bronchiolar involvement was absent, the mean AT score was statistically significantly higher. CONCLUSIONS: Areas of AT represent a new and indirect HRCT finding--and in rare cases the only finding--of pulmonary WG. The nonsignificant correlation between AT extent and inspiratory findings may suggest AT as an additional HRCT finding in patients with WG.

[Comparison of 2D and 3D sequences for MRCP. Clinical value of the different techniques]. / Vergleich von 2D- und 3D-Sequenzen für die MRCP. Klinischer Stellenwert der einzelnen Techniken.

Magnetic resonance cholangio-pancreaticograpy (MRCP) is a non-invasive imaging modality of the pancreatico-biliary system which plays an increasingly important role in the clinical and diagnostic workup of patients with biliary or pancreatic diseases. The present review is designed to give an overview of the currently available and appropriate sequences, their technical background, as well as new developments and their relevance to the various clinical issues and challenges. The impact of the latest technical innovations, such as integrated parallel imaging techniques and navigator-based respiratory triggering, on the diagnostic capacities of MRCP is discussed. In this context, the individual value of RARE, T2w single shot turbo/fast spin echo (SSFSE) and the recently introduced 3D T2w turbo/fast spin echo sequences (T2w 3D-T/FSE) is reviewed. RARE imaging may be preferred in severely ill patients with limitations in cooperation, SSFSE is particularly effective in differentiating benign and malignant stenosis, and 3D-FSE offers additional advantages in the detection of small biliary concrements.