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.

Height of Rectal Cancer: A Comparison between Rectoscopic and Different MRI Measurements.

PURPOSE: To compare rigid rectoscopy with three different MRI measurement techniques for rectal cancer height determination, all starting at the anal verge, in order to evaluate whether MRI measurements starting from the anal verge could be an alternative to rigid rectoscopy. Moreover, potential cut-off values for MRI in categorizing tumor height measurements were evaluated. METHODS: In this retrospective study, 106 patients (75 men, 31 female, mean age 64 ± 11.59 years) with primary rectal cancer underwent rigid rectoscopy as well as MR imaging. Three different measurements (MRI1-3) in T2w sagittal scans were used to evaluate the exact distance from the anal verge (AV) to the distal ending of the tumor (MRI1: two unbowed lines, AV to the upper ending of the anal canal and upper ending of the anal canal to the lower border of the tumor; MRI2: one straight line from the AV to the lower boarder of the tumor; MRI3: a curved line beginning at the AV and following the course of the rectum wall ending at the lower border of the tumor). Furthermore, agreement between the gold standard rigid rectoscopy (UICC classification: low part, 0-6 cm; mid part, 6-12 cm; and high part, >12 cm) and each MRI measuring technique was analyzed. RESULTS: Only a fair correlation in terms of individual measures between rectoscopy and all 3 MRI measurement techniques was shown. The proposed new cut-off values utilizing ROC analysis for the three different MRI beginning at the anal verge were low 0-7.7 cm, mid 7.7-13.3 cm, and high > 13.3 cm (MRI1); low 0-7.4 cm, mid 7.4-11.2 cm, and high > 11.2 cm (MRI2); and low 0-7.1 cm, mid 7.1-13.7 cm, and high > 13.7 cm (MRI3). For MRI1 and MRI3, the agreement to the gold standard was substantial (r = 0.66, r = 0.67, respectively). CONCLUSION: This study illustrates that MRI1 and MRI3 measures can be interchangeably used as a valid method to determine tumor height compared to the gold standard rigid rectoscopy.

Prostate cancer detection among readers with different degree of experience using ultra-high b-value diffusion-weighted Imaging: Is a non-contrast protocol sufficient to detect significant cancer?

AIM: To evaluate the accuracy of a T2-weighted (T2w) - and a parallel transmit zoomed b = 2000 s/mm2 (b2000) - diffusion-weighted imaging sequence among three readers with different degrees of experience for prostate cancer (Pca) detection. METHODS: Ninety-three patients with suspected Pca were enrolled. For b2000 a two-dimensional spatially-selective RF pulse using an echo-planar transmit trajectory was applied, and the field of view (FOV) was reduced to one-third. All three readers (Reader A: 7, B 4 and C <1 years of experience in prostate MRI) independently evaluated b2000 with regard to the presence of suspicious lesions that displayed increased signal. The results were compared to histopathology obtained by real-time MR/ultrasound fusion and systematic biopsy. RESULTS: In 62 patients Pca was confirmed. One significant Pca (Gleason score (GS) 7b) was missed by Reader C. Overall, sensitivity/specificity/positive predictive value/negative predictive value were 90/71/86/79% for Reader A, 87/84/92/76% for Reader B and 85/74/87/72% for Reader C, respectively. Detection rates for significant Pca (GS >7a) were 100/100/94% for Readers A/B/C, respectively. Inter-reader agreement was generally good (Kappa A/B: 0.8; A/C: 0.82; B/C: 0.74). CONCLUSION: B2000 in combination with a T2w could be useful to detect clinically significant Pca. KEY POINTS: • Significant prostate cancer using zoomed ultra-high b-value DWI was detected. • Diagnostic performance among readers with different degrees of experience was good. • mp- MRI of the prostate using a comprehensive non-contrast protocol is clinically feasible.

[CT and MRI of the liver: when, what, why?] / CT und MRT der Leber: wann, was, warum?

The detection and differential diagnostic clarification of liver pathologies play an important role in almost all medical disciplines. Because of its superior soft tissue contrast, the availability of liver-specific contrast agents and functional techniques, magnetic resonance imaging (MRI) is the method of choice for the diagnostics of focal and diffuse liver pathologies. In addition to its superior detection and differentiation capabilities, MRI can provide prognostic information and enable early assessment of the therapy response for malignant liver lesions using functional techniques, especially diffusion imaging. Computed tomography (CT) is the imaging method of choice for the detection of traumatic liver injury. Despite the increasing availability of functional techniques in CT, MRI remains the overall modality of choice in liver imaging.

[Importance of diffusion imaging in liver metastases]. / Bedeutung der Diffusionsbildgebung bei Lebermetastasen.

CLINICAL/METHODICAL ISSUE: Detection and characterization of focal liver lesions. STANDARD RADIOLOGICAL METHODS: Due to its excellent soft tissue contrast, the availability of liver-specific contrast agents and the possibility of functional imaging, magnetic resonance imaging (MRI) is the method of choice for the evaluation of focal liver lesions. METHODICAL INNOVATIONS: Diffusion-weighted imaging (DWI) enables generation of functional information about the microstructure of a tissue besides morphological information. PERFORMANCE: In the detection of focal liver lesions DWI shows a better detection rate compared to T2w sequences and a slightly poorer detection rate compared to dynamic T1w sequences. In principle, using DWI it is possible to distinguish malignant from benign liver lesions and also to detect a therapy response at an early stage. ACHIEVEMENTS: For both detection and characterization of focal liver lesions, DWI represents a promising alternative to the morphological sequences; however, a more detailed characterization with the use of further sequences should be carried out particularly for the characterization of solid benign lesions. For the assessment and prognosis of therapy response, DWI offers advantages compared to morphological sequences. PRACTICAL RECOMMENDATIONS: For the detection of focal liver lesions DWI is in principle sufficient. After visual detection of a solid liver lesion a more detailed characterization should be carried out using further sequences (in particular dynamic T1w sequences). The DWI procedure should be used for the assessment and prognosis of a therapy response.

Image quality of mean temporal arterial and mean temporal portal venous phase images calculated from low dose dynamic volume perfusion CT datasets in patients with hepatocellular carcinoma and pancreatic cancer.

PURPOSE: Dynamic volume perfusion CT (dVPCT) provides valuable information on tissue perfusion in patients with hepatocellular carcinoma (HCC) and pancreatic cancer. However, currently dVPCT is often performed in addition to conventional CT acquisitions due to the limited morphologic image quality of dose optimized dVPCT protocols. The aim of this study was to prospectively compare objective and subjective image quality, lesion detectability and radiation dose between mean temporal arterial (mTA) and mean temporal portal venous (mTPV) images calculated from low dose dynamic volume perfusion CT (dVPCT) datasets with linearly blended 120-kVp arterial and portal venous datasets in patients with HCC and pancreatic cancer. MATERIALS AND METHODS: All patients gave written informed consent for this institutional review board-approved HIPAA compliant study. 27 consecutive patients (18 men, 9 women, mean age, 69.1 years±9.4) with histologically proven HCC or suspected pancreatic cancer were prospectively enrolled. The study CT protocol included a dVPCT protocol performed with 70 or 80kVp tube voltage (18 spiral acquisitions, 71.2s total acquisition times) and standard dual-energy (90/150kVpSn) arterial and portal venous acquisition performed 25min after the dVPCT. The mTA and mTPV images were manually reconstructed from the 3 to 5 best visually selected single arterial and 3 to 5 best single portal venous phases dVPCT dataset. The linearly blended 120-kVp images were calculated from dual-energy CT (DECT) raw data. Image noise, SNR, and CNR of the liver, abdominal aorta (AA) and main portal vein (PV) were compared between the mTA/mTPV and the linearly blended 120-kVp dual-energy arterial and portal venous datasets, respectively. Subjective image quality was evaluated by two radiologists regarding subjective image noise, sharpness and overall diagnostic image quality using a 5-point Likert Scale. In addition, liver lesion detectability was performed for each liver segment by the two radiologists using the linearly blended120-kVp arterial and portal venous datasets as the reference standard. RESULTS: Image noise, SNR and CNR values of the mTA and mTPV were significantly higher when compared to the corresponding linearly blended arterial and portal venous 120-kVp datasets (all p<0.001) except for image noise within the PV in the portal venous phases (p=0.136). OBJECTIVE: image quality of mTA and mTPV were rated significantly better when compared to the linearly blended 120-kVp arterial and portal venous datasets. Both readers were able to detect all liver lesions found on the linearly blended 120-kVp arterial and portal venous datasets using the mTA and mTPV datasets. The effective radiation dose of the dVPCT was 27.6mSv for the 80kVp protocol and 14.5mSv for the 70kVp protocol. The mean effective radiation dose for the linearly blended 120-kVp arterial and portal venous CT protocol together of the upper abdomen was 5.60mSv±1.48mSv. CONCLUSION: Our preliminary data suggest that subjective and objective image quality of mTA and mTPV datasets calculated from low-kVp dVPCT datasets is non-inferior when compared to linearly blended 120-kVp arterial and portal venous acquisitions in patients with HCC and pancreatic cancer. Thus, dVPCT could be used as a stand-alone imaging technique without additionally performed conventional arterial and portal venous CT acquisitions.

Splenomegaly, elevated alkaline phosphatase and mutations in the SRSF2/ASXL1/RUNX1 gene panel are strong adverse prognostic markers in patients with systemic mastocytosis.

We evaluated the impact of clinical and molecular characteristics on overall survival (OS) in 108 patients with indolent (n=41) and advanced systemic mastocytosis (SM) (advSM, n=67). Organomegaly was measured by magnetic resonance imaging-based volumetry of the liver and spleen. In multivariate analysis of all patients, an increased spleen volume ⩾450 ml (hazard ratio (HR), 5.2; 95% confidence interval (CI), (2.1-13.0); P=0.003) and an elevated alkaline phosphatase (AP; HR 5.0 (1.1-22.2); P=0.02) were associated with adverse OS. The 3-year OS was 100, 77, and 39%, respectively (P<0.0001), for patients with 0 (low risk, n=37), 1 (intermediate risk, n=32) or 2 (high risk, n=39) parameters. For advSM patients with fully available clinical and molecular data (n=60), univariate analysis identified splenomegaly ⩾1200 ml, elevated AP and mutations in the SRSF2/ASXL1/RUNX1 (S/A/R) gene panel as significant prognostic markers. In multivariate analysis, mutations in S/A/R (HR 3.2 (1.1-9.6); P=0.01) and elevated AP (HR 2.6 (1.0-7.1); P=0.03) remained predictive adverse prognostic markers for OS. The 3-year OS was 76 and 38%, respectively (P=0.0003), for patients with 0-1 (intermediate risk, n=28) or 2 (high risk, n=32) parameters. We conclude that splenomegaly, elevated AP and mutations in the S/A/R gene panel are independent of the World Health Organization classification and provide the most relevant prognostic information in SM patients.

Comparison of organ-specific-radiation dose levels between 70 kVp perfusion CT and standard tri-phasic liver CT in patients with hepatocellular carcinoma using a Monte-Carlo-Simulation-based analysis platform.

PURPOSE: The aim of this study was to systematically compare organ-specific-radiation dose levels between a radiation dose optimized perfusion CT (dVPCT) protocol of the liver and a tri-phasic standard CT protocol of the liver using a Monte-Carlo-Simulation-based analysis platform. METHODS AND MATERIALS: The complete CT data of 52 patients (41 males; mean age 65 ± 12) with suspected HCC that underwent dVPCT examinations on a 3rd generation dual-source CT (Somatom Force, Siemens) with a dose optimized tube voltage of 70 kVp or 80 kVp were exported to an analysis platform (Radimetrics, Bayer). The dVPCT studies were matched with a reference group of 50 patients (35 males; mean age 65 ± 14) that underwent standard tri-phasic CT (sCT) examinations of the liver with 130 kVp using the calculated water-equivalent-diameter of the patients. The analysis platform was used for the calculation of the organ-specific effective dose (ED) as well as global radiation-dose parameters (ICRP103). RESULTS: The organ-specific ED of the dVPCT protocol was statistically significantly lower when compared to the sCT in 14 of 21, and noninferior in a total of 18 of 21 examined items (all p < 0.05). The EDs of the dVPCT examinations were especially in the dose sensitive organs such as the red marrow (17.3 mSv vs 24.6 mSv, p = < 0.0001) and the liver (33.3 mSv vs 46.9 mSv, p = 0.0003) lower when compared to the sCT. CONCLUSION: Our results suggest that dVPCT performed at 70 or 80 kVp compares favorably to sCT performed with 130 kVp with regard to effective organ dose levels, especially in dose sensitive organs, while providing additional functional information which is of paramount importance in patients undergoing novel targeted therapies.

Region of interest-based versus whole-lung segmentation-based approach for MR lung perfusion quantification in 2-year-old children after congenital diaphragmatic hernia repair.

OBJECTIVE: With a region of interest (ROI)-based approach 2-year-old children after congenital diaphragmatic hernia (CDH) show reduced MR lung perfusion values on the ipsilateral side compared to the contralateral. This study evaluates whether results can be reproduced by segmentation of whole-lung and whether there are differences between the ROI-based and whole-lung measurements. METHODS: Using dynamic contrast-enhanced (DCE) MRI, pulmonary blood flow (PBF), pulmonary blood volume (PBV) and mean transit time (MTT) were quantified in 30 children after CDH repair. Quantification results of an ROI-based (six cylindrical ROIs generated of five adjacent slices per lung-side) and a whole-lung segmentation approach were compared. RESULTS: In both approaches PBF and PBV were significantly reduced on the ipsilateral side (p always <0.0001). In ipsilateral lungs, PBF of the ROI-based and the whole-lung segmentation-based approach was equal (p=0.50). In contralateral lungs, the ROI-based approach significantly overestimated PBF in comparison to the whole-lung segmentation approach by approximately 9.5 % (p=0.0013). CONCLUSIONS: MR lung perfusion in 2-year-old children after CDH is significantly reduced ipsilaterally. In the contralateral lung, the ROI-based approach significantly overestimates perfusion, which can be explained by exclusion of the most ventral parts of the lung. Therefore whole-lung segmentation should be preferred. KEY POINTS: • Ipsilaterally, absolute lung perfusion after CDH is reduced in whole-lung analysis. • Ipsilaterally, the ROI- and whole-lung-based approaches generate identical results. • Contralaterally, the ROI-based approach significantly overestimates perfusion results. • Whole lung should be analysed in MR lung perfusion imaging. • MR lung perfusion measurement is a radiation-free parameter of lung function.

[Quantitative perfusion imaging in magnetic resonance imaging]. / Quantitative Perfusionsbildgebung in der Magnetresonanztomographie.

CLINICAL/METHODICAL ISSUE: Magnetic resonance imaging (MRI) is recognized for its superior tissue contrast while being non-invasive and free of ionizing radiation. Due to the development of new scanner hardware and fast imaging techniques during the last decades, access to tissue and organ functions became possible. One of these functional imaging techniques is perfusion imaging with which tissue perfusion and capillary permeability can be determined from dynamic imaging data. STANDARD RADIOLOGICAL METHODS: Perfusion imaging by MRI can be performed by two approaches, arterial spin labeling (ASL) and dynamic contrast-enhanced (DCE) MRI. While the first method uses magnetically labelled water protons in arterial blood as an endogenous tracer, the latter involves the injection of a contrast agent, usually gadolinium (Gd), as a tracer for calculating hemodynamic parameters. PERFORMANCE: Studies have demonstrated the potential of perfusion MRI for diagnostics and also for therapy monitoring. ACHIEVEMENTS: The utilization and application of perfusion MRI are still restricted to specialized centers, such as university hospitals. A broad application of the technique has not yet been implemented. PRACTICAL RECOMMENDATIONS: The MRI perfusion technique is a valuable tool that might come broadly available after implementation of standards on European and international levels. Such efforts are being promoted by the respective professional bodies.

The value of dynamic magnetic resonance imaging in interdisciplinary treatment of pelvic floor dysfunction.

PURPOSE: The purpose of this study was to determine the value of dynamic pelvic floor MRI relative to standard clinical examinations in treatment decisions made by an interdisciplinary team of specialists in a center for pelvic floor dysfunction. METHODS: 60 women were referred for dynamic pelvic floor MRI by an interdisciplinary team of specialists of a pelvic floor center. All patients were clinically examined by an urologist, gynecologist, a proctological, and colorectal surgeon. The specialists assessed individually and in consensus, whether (1) MRI provides important additional information not evident by physical examination and in consensus whether (2) MRI influenced the treatment strategy and/or (3) changed management or the surgical procedure. RESULTS: MRI was rated essential to the treatment decision in 22/50 cases, leading to a treatment change in 13 cases. In 12 cases, an enterocele was diagnosed by MRI but was not detected on physical exam. In 4 cases an enterocele and in 2 cases a rectocele were suspected clinically but not confirmed by MRI. In 4 cases, MRI proved critical in assessment of rectocele size. Vaginal intussusception detected on MRI was likewise missed by gynecologic exam in 1 case. CONCLUSION: MRI allows diagnosis of clinically occult enteroceles, by comprehensively evaluating the interaction between the pelvic floor and viscera. In nearly half of cases, MRI changed management or the surgical approach relative to the clinical evaluation of an interdisciplinary team. Thus, dynamic pelvic floor MRI represents an essential component of the evaluation for pelvic floor disorders.

(18) F-FDG PET/CT for initial staging in breast cancer patients - Is there a relevant impact on treatment planning compared to conventional staging modalities?

OBJECTIVE: To evaluate the impact of whole-body (18) F-FDG PET/CT on initial staging of breast cancer in comparison to conventional staging modalities. METHODS: This study included 102 breast cancer patients, 101 patients were eligible for evaluation. Preoperative whole-body staging with PET/CT was performed in patients with clinical stage ≥ T2 tumours or positive local lymph nodes (n = 91). Postoperative PET/CT was performed in patients without these criteria but positive sentinel lymph node biopsy (n = 10). All patients underwent PET/CT and a conventional staging algorithm, which included bone scan, chest X-ray and abdominal ultrasound. PET/CT findings were compared to conventional staging and the impact on therapeutic management was evaluated. RESULTS: PET/CT led to an upgrade of the N or M stage in overall 19 patients (19 %) and newly identified manifestation of breast cancer in two patients (2 %). PET/CT findings caused a change in treatment of 11 patients (11 %). This is within the range of recent studies, all applying conventional inclusion criteria based on the initial T and N status. CONCLUSIONS: PET/CT has a relevant impact on initial staging and treatment of breast cancer when compared to conventional modalities. Further studies should assess inclusion criteria beyond the conventional T and N status, e.g. tumour grading and receptor status. KEY POINTS: • PET/CT may be relevant in staging breast cancer patients at higher risk for metastases • PET/CT may modify the N and M stage in multiple patients • PET/CT may impact treatment planning in breast cancer patients.

DCE-MRI of the breast in a stand-alone setting outside a complementary strategy - results of the TK-study.

OBJECTIVES: To evaluate the accuracy of MRI of the breast (DCE-MRI) in a stand-alone setting with extended indications. MATERIALS AND METHODS: According to the inclusion criteria, breast specialists were invited to refer patients to our institution for DCE-MRI. Depending on the MR findings, patients received either a follow-up or biopsy. Between 04/2006 and 12/2011 a consecutive total of 1,488 women were prospectively examined. RESULTS: Of 1,488 included patients, 393 patients were lost to follow-up, 1,095 patients were evaluated. 124 patients were diagnosed with malignancy by DCE-MRI (76 TP, 48 FP, 971 TN, 0 FN cases). Positive cases were confirmed by histology, negative cases by MR follow-ups or patient questionnaires over the next 5 years in 1,737 cases (sensitivity 100 %; specificity 95.2 %; PPV 61.3 %; NPV 100 %; accuracy 95.5 %). For invasive cancers only (DCIS excluded), the results were 63 TP; 27 FP; 971 TP and 0 FN (sensitivity 100 %; specificity 97.2 %; PPV 70 %; NPV 100 %; accuracy 97.5 %). CONCLUSION: The DCE-MRI indications tested imply that negative results in DCE-MRI reliably exclude cancer. The results were achieved in a stand-alone setting (single modality diagnosis). However, these results are strongly dependent on reader experience and adequate technical standards as prerequisites for optimal diagnoses. KEY POINTS: • DCE-MRI of the breast has a high accuracy in finding breast cancer. • The set of indications for DCE-MRI of the breast is still very limited. • DCE-MRI can achieve a high accuracy in a 'screening-like' setting. • Accuracy of breast DCE-MRI is strongly dependent on technique and reader experience. • A negative DCE-MRI effectively excludes cancer.

High temporal versus high spatial resolution in MR quantitative pulmonary perfusion imaging of two-year old children after congenital diaphragmatic hernia repair.

OBJECTIVES: Congenital diaphragmatic hernia (CDH) leads to lung hypoplasia. Using dynamic contrast-enhanced (DCE) MR imaging, lung perfusion can be quantified. As MR perfusion values depend on temporal resolution, we compared two protocols to investigate whether ipsilateral lung perfusion is impaired after CDH, whether there are protocol-dependent differences, and which protocol is preferred. METHODS: DCE-MRI was performed in 36 2-year old children after CDH on a 3 T MRI system; protocol A (n = 18) based on a high spatial (3.0 s; voxel: 1.25 mm(3)) and protocol B (n = 18) on a high temporal resolution (1.5 s; voxel: 2 mm(3)). Pulmonary blood flow (PBF), pulmonary blood volume (PBV), mean transit time (MTT), and peak-contrast-to-noise-ratio (PCNR) were quantified. RESULTS: PBF was reduced ipsilaterally, with ipsilateral PBF of 45 ± 26 ml/100 ml/min to contralateral PBF of 63 ± 28 ml/100 ml/min (p = 0.0016) for protocol A; and for protocol B, side differences were equivalent (ipsilateral PBF = 62 ± 24 vs. contralateral PBF = 85 ± 30 ml/100 ml/min; p = 0.0034). PCNR was higher for protocol B (30 ± 18 vs. 20 ± 9; p = 0.0294). Protocol B showed higher values of PBF in comparison to protocol A (p always <0.05). CONCLUSIONS: Ipsilateral lung perfusion is reduced in 2-year old children following CDH repair. Higher temporal resolution and increased voxel size show a gain in PCNR and lead to higher perfusion values. Protocol B is therefore preferred. KEY POINTS: • Quantitative lung perfusion parameters depend on temporal and spatial resolution. • Reduction of lung perfusion in CDH can be measured with different MR protocols. • Temporal resolution of 1.5 s with spatial resolution of 2 mm (3) is suitable.

Multi-parametric MRI of rectal cancer - do quantitative functional MR measurements correlate with radiologic and pathologic tumor stages?

PURPOSE: The purpose of this study is two-fold. First, to evaluate, whether functional rectal MRI techniques can be analyzed in a reproducible manner by different readers and second, to assess whether different clinical and pathologic T and N stages can be differentiated by functional MRI measurements. MATERIALS AND METHODS: 54 patients (38 men, 16 female; mean age 63.2 ± 12.2 years) with pathologically proven rectal cancer were included in this retrospective IRB-approved study. All patients were referred for a multi-parametric MRI protocol on a 3 Tesla MR-system, consisting of a high-resolution, axial T2 TSE sequence, DWI and perfusion imaging (plasma flow -s PFTumor) prior to any treatment. Two experienced radiologists evaluated the MRI measurements, blinded to clinical data and outcome. Inter-reader correlation and the association of functional MRI parameters with c- and p-staging were analyzed. RESULTS: The inter-reader correlation for lymph node (ρ 0.76-0.94; p<0.0002) and primary tumor (ρ 0.78-0.92; p<0.0001) apparent diffusion coefficient and plasma flow (PF) values was good to very good. PFTumor values decreased with cT stage with significant differences identified between cT2 and cT3 tumors (229 versus 107.6 ml/100ml/min; p=0.05). ADCTumor values did not differ significantly. No substantial discrepancies in lymph node ADCLn values or short axis diameter were found among cN1-3 stages, whereas PFLn values were distinct between cN1 versus cN2 stages (p=0.03). In the patients without neoadjuvant RCT no statistically significant differences in the assessed functional parameters on the basis of pathologic stage were found. CONCLUSION: This study illustrates that ADC as well as MR perfusion values can be analyzed with good interobserver agreement in patients with rectal cancer. Moreover, MR perfusion parameters may allow accurate differentiation of tumor stages. Both findings suggest that functional MRI parameters may help to discriminate T and N stages for clinical decision making.

Whole-body CT for lymphoma staging: feasibility of halving radiation dose and risk by iterative image reconstruction.

OBJECTIVES: Patients with lymphoma are at higher-risk of secondary malignancies mainly due to effects of cancer therapy as well as frequent radiological surveillance. We thus aimed to investigate the objective and subjective image quality as well as radiation exposure and risk of full-dose standard (FDS), full-dose iterative (FDI), and half-dose iterative (HDI) image reconstruction in patients with lymphoma. MATERIAL AND METHODS: In 100 lymphoma patients, contrast-enhanced whole-body staging was performed on a dual-source CT. To acquire full-dose and half-dose CT data simultaneously, the total current-time product was equally distributed on both tubes operating at 120 kV. HDI reconstructions were calculated by using only data from one tube. Quantitative image quality was assessed by measuring image noise in different tissues of the neck, thorax, and abdomen. Overall diagnostic image quality was assessed using a 5-point Likert scale. Radiation doses and risks were estimated for a male and female reference person. RESULTS: For all anatomical regions apart from the lungs image noise was significantly lower and the overall subjective image quality significantly better when using FDI and HDI instead of FDS reconstruction (p<0.05). For the half-dose protocol, the risk to develop a radiation-induced cancer was estimated to be less than 0.11/0.19% for an adult male/female. CONCLUSIONS: Image quality of FDI and more importantly of HDI is superior to FDS reconstruction, thus enabling to halve radiation dose and risk to lymphoma patients.

3 Tesla proton MRI for the diagnosis of pneumonia/lung infiltrates in neutropenic patients with acute myeloid leukemia: initial results in comparison to HRCT.

PURPOSE: To evaluate the diagnostic accuracy of 3 Tesla proton MRI for the assessment of pneumonia/lung infiltrates in neutropenic patients with acute myeloid leukemia. MATERIAL AND METHODS: In a prospective study, 3 Tesla MRI was performed in 19 febrile neutropenic patients (5 women, 14 men; mean age 61 years ± 14.2; range 23-77 years). All patients underwent high-resolution CT less than 24h prior to MRI. The MRI protocol (Magnetom Tim Trio, Siemens) included a T2-weighted HASTE sequence (TE/TR: 49 ms/∞, slice thickness 6mm) and a high-resolution 3D VIBE sequence with an ultra-short TE<1 ms (TE/TR 0.8/2.9 ms, slice thickness 2mm). The VIBE sequence was examined before and after intravenous injection of 0.1 mmol/kg gadoterate meglumine (Dotarem, Guerbet). The presence of pulmonary abnormalities, their location within the lung, and lesion type (nodules, consolidations, glass opacity areas) were analyzed by one reader and compared to the findings of HRCT, which was evaluated by a second independent radiologist who served as the reference standard. The findings were compared per lobe in each patient and rated as true positive (TP) findings if all three characteristics (presence, location, and lesion type) listed above were concordant to HRCT. RESULTS: Pulmonary abnormalities were characterized by 3 Tesla MRI with a sensitivity of 82.3% and a specificity of 78.6%, resulting in an overall accuracy of 88% (NPV/PPV 66.7%/89.5%). In 51 lobes (19 of 19 patients), pulmonary abnormalities visualized by MR were judged to be concordant in their location and in the lesion type identified by both readers. In 22 lobes (11 of 19 patients), no abnormalities were present on either MR or HRCT (true negative). In 6 lobes (5 of 19 patients), ground glass opacity areas were detected on MRI but were not visible on HRCT (false positives). In 11 lobes (7 of 19 patients), MRI failed to detect ground glass opacity areas identified by HRCT. However, since the abnormalities were disseminated in these patients, accurate treatment decisions were possible in every case based on MRI. In one case MRI showed a central area of cavitation, which was not visualized by HRCT. CONCLUSION: Infectious nodules and consolidations can be detected in neutropenic patients with acute myeloid leukemia with a sufficient diagnostic accuracy by 3 Tesla MRI. Detection of ground glass opacity areas is the main limitation of 3-Tesla MRI when compared to HRCT.

Diffusion-weighted imaging of focal renal lesions: a meta-analysis.

OBJECTIVES: Contrast-enhanced MRI can only distinguish to a limited extent between malignant and benign focal renal lesions. The aim of this meta-analysis is to review renal diffusion-weighted imaging (DWI) to compare apparent diffusion coefficient (ADC) values for different renal lesions that can be applied in clinical practice. METHODS: A PubMed search was performed to identify relevant articles published 2004-2011 on renal DWI of focal renal lesions. ADC values were extracted by lesion type to determine whether benign or malignant. The data table was finalised in a consensus read. ADC values were evaluated statistically using meta-regression based on a linear mixed model. Two-sided P value <5 % indicated statistical significance. RESULTS: The meta-analysis is based on 17 studies with 764 patients. Renal cell carcinomas have significant lower ADC values than benign tissue (1.61 ± 0.08 × 10(-3) mm(2)/s vs 2.10 ± 0.09 × 10(-3) mm(2)/s; P < 0.0001). Uroepithelial malignancies can be differentiated by lowest ADC values (1.30 ± 0.11 × 10(-3) mm(2)/s). There is a significant difference between ADC values of renal cell carcinomas and oncocytomas (1.61 ± 0.08 × 10(-3) mm(2)/s vs 2.00 ± 0.08 × 10(-3) mm(2)/s; P < 0.0001). CONCLUSIONS: Evaluation of ADC values can help to determine between benign and malignant lesions in general but also seems able to differentiate oncocytomas from malignant tumours, hence potentially reducing the number of unnecessarily performed nephrectomies. KEY POINTS: • This meta-analysis assesses the role of diffusion-weighted MRI in renal lesions. • ADC values obtained by DW MRI have been compared for different renal lesions. • ADC values can help distinguish between benign and malignant tumours. • Differentiating oncocytomas from malignant tumours can potentially reduce inappropriate nephrectomies.

[Value of new MR techniques in MR-PET]. / Stellenwert neuer MR-Techniken in der MR-PET.

The unparalleled soft tissue contrast of magnetic resonance imaging (MRI) and the functional information obtainable with 18-F fluorodeoxyglucose positron emission tomography (FDG-PET) render MR-PET well-suited for oncological and psychiatric imaging. The lack of ionizing radiation with MRI also makes MR-PET a promising modality for oncology patients requiring frequent follow-up and pediatric patients. Lessons learned with PET computed tomography (CT) over the last few years do not directly translate to MR-PET. For example, in PET-CT the Hounsfield units derived from CT are used for attenuation correction (AC). As 511 keV photons emitted in PET examinations are attenuated by the patient's body CT data are converted directly to linear attenuation coefficients (LAC); however, proton density measured by MRI is not directly related to the radiodensity or LACs of biological tissue. Thus, direct conversion to LAC data is not possible making AC more challenging in simultaneous MRI-PET scanning. In addition to these constraints simultaneous MRI-PET acquisitions also improve on some solutions to well-known challenges of hybrid imaging techniques, such as limitations in motion correction. This article reports on initial clinical experiences with simultaneously acquired MRI-PET data, focusing on the potential benefits and limitations of MRI with respect to motion correction as well as metal and attenuation correction artefacts.

Axillary lymph node characterization in breast cancer patients using magnetic resonance mammography: a prospective comparative study with FDG PET-CT and healthy women.

OBJECTIVE: The aim of this study was to evaluate the capability of dynamic contrast enhanced MR-mammography (MRM) for the interpretation of axillary lymph nodes (LNs) in patients with breast cancer. MATERIAL AND METHODS: 25 patients with breast cancer preoperatively underwent both FDG positron emission computed tomography (PET-CT) and dynamic contrast enhanced MRM. The maximum signal increase (SImax) and curve shape (types I-III) of contrast enhanced LNs ≥ 0.5 cm (short-axis) were analyzed in MRM and correlated to the maximum standard uptake value (SUVmax) of FDG PET-CT. 29 healthy women with MRM served as control group. Enhancement kinetics of all malignant LNs were compared to LN findings of the healthy control group. RESULTS: Overall 33 contrast enhanced LNs on preoperative MRM had a corresponding FDG uptake on PET-CT. 30 of the PET positive LNs were classified as surely malignant (mean SUVmax 7.3 (± 5.4)). The mean SImax of these LNs was not significantly different to the control group (222% vs 197%), but malignant LNs had a significantly higher rate of type III curves with rapid washout (93% vs 66%, p = 0.008). CONCLUSION: The maximum signal increase is not capable of differentiating malignant from benign axillary LNs. However, since malignant LNs showed a higher frequency of rapid washout curves (type III curves) on corresponding MRM future studies should concentrate on the analysis of this parameter. In clinical routine the curve shape still should be taken with care as there is a high overlap with benign LNs.