Protocol requirements and diagnostic value of PET/MR imaging for liver metastasis detection

Purpose

To compare the accuracy of PET/MR imaging with that of FDG PET/CT and to determine the MR sequences necessary for the detection of liver metastasis using a trimodality PET/CT/MR set-up.

Methods

Included in this single-centre IRB-approved study were 55 patients (22 women, age 61?±?11 years) with suspected liver metastases from gastrointestinal cancer. Imaging using a trimodality PET/CT/MR set-up (time-of-flight PET/CT and 3-T whole-body MR imager) comprised PET, low-dose CT, contrast-enhanced (CE) CT of the abdomen, and MR with T1-W/T2-W, diffusion-weighted (DWI), and dynamic CE imaging. Two readers evaluated the following image sets for liver metastasis: PET/CT (set A), PET/CECT (B), PET/MR including T1-W/T2-W (C), T1-W/T2-W with either DWI (D) or CE imaging (E), and a combination (F). The accuracy of each image set was determined by receiver-operating characteristic analysis using image set B as the standard of reference.

Results

Of 120 liver lesions in 21/55 patients (38 %), 79 (66 %) were considered malignant, and 63/79 (80 %) showed abnormal FDG uptake. Accuracies were 0.937 (95 % CI 89.5 – 97.9 %) for image set A, 1.00 (95 % CI 99.9 – 100.0 %) for set C, 0.998 (95 % CI 99.4 – 100.0 %) for set D, 0.997 (95 % CI 99.3 – 100.0 %) for set E, and 0.995 (95 % CI 99.0 – 100.0 %) for set F. Differences were significant for image sets D – F (P?<?0.05) when including lesions without abnormal FDG uptake. As shown by follow-up imaging after 50 – 177 days, the use of image sets D and both sets E and F led to the detection of metastases in one and three patients, respectively, and further metastases in the contralateral lobe in two patients negative on PET/CECT (P?=?0.06).

Conclusion

PET/MR imaging with T1-W/T2-W sequences results in similar diagnostic accuracy for the detection of liver metastases to PET/CECT. To significantly improve the characterization of liver lesions, we recommend the use of dynamic CE imaging sequences. PET/MR imaging has a diagnostic impact on clinical decision making.     

Detection of liver metastasis: is diffusion-weighted imaging needed in Gd-EOB-DTPA-enhanced MR imaging for evaluation of colorectal liver metastases?

Purpose

We compared diagnostic ability for detecting hepatic metastases between gadolinium ethoxy benzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) on a 1.5-T system, and determined whether DWI is necessary in Gd-EOB-DTPA-enhanced MRI for diagnosing colorectal liver metastases.

Materials and methods

We assessed 29 consecutive prospectively enrolled patients with suspected metachronous colorectal liver metastases; all patients underwent surgery and had preoperative Gd-EOB-DTPA-enhanced MRI. Overall detection rate, sensitivity for detecting metastases and benign lesions, positive predictive value, and diagnostic accuracy (Az value) were compared among three image sets [unenhanced MRI (DWI set), Gd-EOB-DTPA-enhanced MRI excluding DWI (EOB set), and combined set].

Results

Gd-EOB-DTPA-enhanced MRI yielded better overall detection rate (77.8?C79.0?%) and sensitivity (87.1?C89.4?%) for detecting metastases than the DWI set (55.9?% and 64.7?%, respectively) for one observer (P?<?0.001). No statistically significant difference was seen between the EOB and combined sets, although several metastases were newly detected on additional DWI.

Conclusions

Gd-EOB-DTPA-enhanced MRI yielded a better overall detection rate and higher sensitivity for detecting metastases compared with unenhanced MRI. Additional DWI may be able to reduce oversight of lesions in Gd-EOB-DTPA-enhanced 1.5-T MRI for detecting colorectal liver metastases.     

The value of diffusion-weighted imaging in the detection of prostate cancer: a meta-analysis

Objectives

To evaluate the diagnostic performance of diffusion-weighted imaging (DWI) as a single non-invasive method in detecting prostate cancer (PCa) and to deduce its clinical utility.

Methods

A systematic literature search was performed to identify relevant original studies. Quality of included studies was assessed by QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies). Data were extracted to calculate sensitivity and specificity as well as running the test of heterogeneity and threshold effect. The summary receiver operating characteristic (SROC) curve was drawn and area under SROC curve (AUC) served as a determination of the diagnostic performance of DWI for the detection of PCa.

Results

A total of 21 studies were included, with 27 subsets of data available for analysis. The pooled sensitivity and specificity with corresponding 95 % confidence interval (CI) were 0.62 (95 % CI 0.61–0.64) and 0.90 (95 % CI 0.89–0.90), respectively. Pooled positive likelihood ratio and negative likelihood ratio were 5.83 (95 % CI 4.61–7.37) and 0.30 (95 % CI 0.23–0.39), respectively. The AUC was 0.8991. Significant heterogeneity was observed. There was no notable publication bias.

Conclusions

DWI is an informative MRI modality in detecting PCa and shows moderately high diagnostic accuracy. General clinical application was limited because of the absence of standardized DW-MRI techniques.

Key points

? DWI provides incremental information for the detection and evaluation of PCa ? DWI has moderately high diagnostic accuracy in detecting PCa ? Patient condition, imaging protocols and study design positively influence diagnostic performance ? General clinical application requires optimization of image acquisition and interpretation     

Accuracy and confidence of Gd-EOB-DTPA enhanced MRI and diffusion-weighted imaging alone and in combination for the diagnosis of liver metastases

Purpose

To evaluate the accuracy and confidence in diagnosing liver metastases using combined gadolinium-EOB-DTPA (Gd-EOB-DTPA) enhanced magnetic resonance imaging (MRI)/diffusion-weighted imaging (DWI) in comparison to Gd-EOB-DTPA enhanced MRI and DWI alone.

Materials and methods

Forty-three patients (age, 58 ± 13 years) with 89 liver lesions (28 benign, 61 malignant) underwent liver MRI for suspected liver metastases. Three image sets (DWI, Gd-EOB-DTPA and combined Gd-EOB-DTPA/DWI) in combination with unenhanced T1- and T2-weighted images were reviewed by three readers. Detection rates of focal liver lesions were assessed and diagnostic accuracy was evaluated by calculating the areas under the receiver-operating-characteristics curve (AUC). Confidence in diagnosis was evaluated on a 3-point scale. Histopathology and imaging follow-up served as the standard of reference.

Results

Detection of liver lesions and confidence in final diagnosis for all readers were significantly higher for the combined Gd-EOB-DTPA/DWI dataset than for DWI. The combination of DWI and Gd-EOB-DTPA rendered a significantly higher confidence in final diagnosis (2.44 vs. 2.50) than Gd-EOB-DTPA alone for one reader. For two readers, accuracy in diagnosis of liver metastases was significantly higher for Gd-EOB-DTPA/DWI (AUCs of 0.84 and 0.83) than for DWI datasets (AUCs of 0.73 and 0.72). Adding DWI to Gd-EOB-DTPA did not significantly increase diagnostic accuracy as compared to Gd-EOB-DTPA imaging alone.

Conclusion

Addition of DWI sequences to Gd-EOB-DTPA enhanced MRI did not significantly increase diagnostic accuracy as compared to Gd-EOB-DTPA enhanced MRI alone in the diagnosis of liver metastases. However, the increase in diagnostic confidence might justify acquisition of DWI sequences in a dedicated MRI protocol.     

Diffusion-weighted and T2-weighted MR imaging for colorectal liver metastases detection in a rat model at 7 T: a comparative study using histological examination as reference

Objectives

To compare diffusion-weighted (DW) and T2-weighted MR imaging in detecting colorectal liver metastases in a rat model, using histological examination as a reference method.

Methods

Eighteen rats had four liver injections of colon cancer cells. MR examinations at 7 T included FSE-T2-weighted imaging and SE-DW MR imaging (b?=?0, 20 and 150 s/mm²) and were analysed by two independent readers. Histological examination was performed on 0.4-mm slices. McNemar’s test was used to compare the sensitivities and the Wilcoxon matched pairs test to compare the average number of false-positives per rat.

Results

One hundred and sixty-six liver metastases were identified on histological examination. The sensitivity in detecting liver metastases was significantly higher on DW MR than on T2-weighted images (99/166 (60 %) (reader 1) and 92/166 (55 %) (reader 2) versus 77/166 (46 %), P?≤?0.001), without an increase in false-positives per rat (P?=?0.773/P?=?0.850). After stratification according to metastasis diameter, DW MR imaging had a significantly higher sensitivity than T2-weighted imaging only for metastases with a diameter (0.6–1.2 mm) similar to that of the spatial resolution of MR imaging in the current study.

Conclusions

This MR study with histological correlations shows the higher sensitivity of DW relative to T2-weighted imaging at 7 T for detecting liver metastases, especially small ones.

Key Points

? Diffusion weighted (DW) sequences are increasingly used in magnetic resonance imaging (MRI). ? DW has higher sensitivity for liver metastases than T2-weighted imaging at 7 T. ? This increase in sensitivity is especially marked for small liver metastasis detection. ? This higher sensitivity is confirmed in an animal model with histological correlation. ? DW imaging has the potential for earlier diagnosis of small liver metastases.     

Thermal ablation therapies in patients with breast cancer liver metastases: A review

Background

The liver is involved in about half of patients with metastatic breast cancer. Unfortunately systemic chemotherapy as the treatment of choice is limited. Due to multifocality and/or insufficient remnant liver volume, the majority of liver metastases are also unresectable. Currently, thermal ablations are used in these patients with acceptable impact.

Methods

We reviewed studies on radiofrequency ablation (RFA), laser-induced thermotherapy (LITT) and microwave ablation (MWA) regarding local tumour response, progression and survival indexes in patients with breast cancer liver metastases (BCLM).

Results

The reviewed literature showed positive response rates of 63 % to 97 % in RF-ablated lesions, 98.2 % in LITT-treated lesions and 34.5–62.5 % in MW-ablated lesions. Median survival was 10.9–60 months using RFA, 51–54 months after LITT and 41.8 months using MWA. Five-year survival rates were 27–30 %, 35 % and 29 %, respectively. Local tumour progression ranged from 13.5 % to 58 % using RFA, 2.9 % with LITT and 9.6 % with MWA.

Conclusion

The reviewed literature demonstrated that ablation therapies either as single therapy or combined with other locoregional therapies are a good alternative as an adjunction to resection in patients with resectable lesions or with positive response using chemotherapy. However, multicentre randomised studies should be conducted to obtain further evidence of the benefits of these treatments in patients with BCLM.

Key points

? Thermal ablation is an alternative treatment for hepatic metastases from breast cancer ? This review assesses thermal ablation therapies and local chemoembolisation techniques ? It helps prioritise treatment options for managing hepatic metastases from breast cancer     

Sonoelastography for qualitative and quantitative evaluation of superficial soft tissue lesions: a feasibility study

Objectives

To evaluate the feasibility of qualitative and quantitative analysis using sonoelastography (SE) for differentiating between benign and malignant superficial soft-tissue lesions.

Methods

For this prospective study, 32 patients with superficial soft-tissue lesions detected with grey-scale ultrasound and colour and/or power Doppler ultrasound were evaluated between October 2011 and December 2012. Qualitative analysis: visual grading system was adopted according to colour variation (red-soft, green-medium, blue-hard). Quantitative analysis: median and fraction area of each colour were computed within a region of interest. Differences between fraction areas and median values in compression and decompression phases were calculated. Reference standard: histological findings.

Results

Twelve out of 32 lesions (37.5 %) were malignant. Intraclass correlation coefficient (ICC) was 0.989 (95 % confidence interval [CI] 0.980–0.994, P?<?0.01) with optimal reliability. Area under the curve was 0.823 (95 % CI 0.677–0.969) and 0.958 (95 % CI 0.989–1.019) for blue and blue area differences, and 0.777 (95 % CI 0.615–0.939) and 0.629 (95 % CI 0.426–0.833) for red and red area differences, respectively. Blue variations predicted malignancy more accurately (variation ≥0.431: 100 % sensitivity, 80 % specificity); the blue area difference was highly accurate.

Conclusions

Preliminary results showed good correlations between SE and reference standards. SE could be useful in the evaluation of superficial soft tissue lesions.

Key Points

? Sonoelastography helps clarify ambiguous soft-tissue lesions identified using conventional ultrasound techniques. ? Addition of this tool increases the diagnostic accuracy of ultrasound. ? Sonoelastography provides both qualitative and quantitative analysis. ? Sonoelastography may help clinicians improve patient care.     

Diagnostic performances of shear-wave elastography for identification of malignant breast lesions: a meta-analysis

Purpose

To examine the performance of shear-wave elastography (SWE) for the differentiation of benign and malignant breast lesions using a meta-analysis.

Materials and methods

PubMed, Embase and the Cochrane library were searched for studies published up to January 2014. The references of retrieved relevant articles were reviewed to identify potential publications. Random-effect meta-analysis was conducted to assess the overall sensitivity and specificity of SWE in the differentiation of breast lesions.

Results

A total of 11 articles, including 2424 patients, were included in the present meta-analysis. The summarized sensitivity and specificity of the shear wave elastography performance based on maximum elasticity were 0.93 (95 % CI 0.91–0.95) and 0.81 (95 % CI 0.78–0.83), respectively. For the mean elasticity, the summarized sensitivity and specificity were 0.94 (95 % CI 0.92–0.96) and 0.71 (95 % CI 0.69–0.74), respectively. The summarized sensitivity and specificity were 0.77 (95 % CI 0.70–0.83) and 0.88 (95 % CI 0.84–0.91) for the SD of elasticity.

Conclusion

SWE has a high sensitivity and specificity in the differentiation of benign and malignant breast lesions. More large and prospective studies are warranted to further examine the performance of SWE.     

Comparison of gadolinium-EOB-DTPA-enhanced and diffusion-weighted liver MRI for detection of small hepatic metastases

Objective

To compare the accuracy of gadolinium ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI with that of diffusion-weighted MRI (DWI) in the detection of small hepatic metastases (2 cm or smaller).

Methods

Forty-five patients underwent abdominal MRI at 3 T, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), heavily T2WI (HASTE), DWI with a b-value of 500 s/mm² and contrast-enhanced MRI with Gd-EOB-DTPA. Two groups were assigned and compared: group A (T1WI, T2WI, HASTE and contrast-enhanced study with Gd-EOB-DTPA), and group B (T1WI, T2WI, HASTE and DWI). Two observers independently interpreted the images obtained in a random order. For all hepatic metastases, the diagnostic performance using each imaging set was evaluated by receiver-operating characteristic (ROC) curve analysis.

Results

A total of 51 hepatic metastases were confirmed. The area under the ROC curve (Az) of group A was larger than that of group B, and the difference in the mean Az values between the two image sets was statistically significant, whereas, there were three metastases that lay near thin vessels or among multiple cysts and were better visualised in group B than in group A.

Conclusion

Gd-EOB-DTPA-enhanced MRI showed higher accuracy in the detection of small metastases than DWI.     

Prostate cancer recurrence after radical prostatectomy: the role of 3-T diffusion imaging in multi-parametric magnetic resonance imaging

Objectives

To validate the role of 3-T diffusion-weighted imaging (DWI) in the detection of local prostate cancer recurrence after radical prostatectomy (RP).

Methods

T2-weighted imaging, DWI and dynamic contrast-enhanced MRI (DCE-MRI) were performed with a 3-T magnet in 262 patients after RP. Twenty out of 262 patients evaluated were excluded. MRI results were validated by prostate-specific antigen (PSA) reduction after external beam radiotherapy in group A (126 patients, local recurrence size range 4–8 mm) and by transrectal ultrasound biopsy in group B (116 patients, local recurrence size range 9–15 mm).

Results

In group A combined T2-weighted and DCE-MRI (T2+DCE) shows 98 % sensitivity, 94 % specificity and 93 % accuracy in identifying local recurrence; combined T2-weighted and DWI with a b value of 3,000 s/mm² (T2+DW3) displays 97 % sensitivity, 95 % specificity and 92 % accuracy, while with a b value of 1,000 s/mm² (T2+DW1) affords 93 % sensitivity, 89 % specificity and 88 % accuracy. In group B T2+DCE shows 100 % sensitivity, 97 % specificity and 91 % accuracy in detecting local cancer recurrence; T2+DW3 displays 98 % sensitivity, 96 % specificity and 89 % accuracy; T2+DW1 has 94 % sensitivity, 92 % specificity and 86 % accuracy.

Conclusion

DCE-MRI is the most reliable technique in detecting local prostate cancer recurrence after RP, though DWI can be proposed as a reliable alternative.

Key Points

? Diffusion-weighted magnetic resonance imaging (DWI-MRI) is being increasingly used in oncology. ? PSA analysis does not distinguish prostate cancer recurrence from distant metastasis. ? DWI-MR can diagnose local prostate cancer recurrence after radical prostatectomy. ? DWI-MR is almost comparable to DCE-MRI in detecting local recurrence.     

Diffusion-weighted imaging for the detection of mesenteric small bowel tumours with Magnetic Resonance--enterography

Purpose

To retrospectively investigate the added value of diffusion-weighted MR imaging (DWI) for detecting mesenteric small bowel tumours (MSBTs) via MR-enterography.

Materials and methods

MR-enterographies of 98 patients with suspected MSBTs were blindly analyzed by two independent readers for the presence of MSBTs. Four imaging sets including “standard” (Haste and TrueFisp), “standard + DWI,” “standard + gadolinium-enhanced” and “standard + DWI + gadolinium-enhanced” were reviewed. Diagnostic performance of different readings were compared with McNemar’s test.

Results

Twenty-nine MSBTs were pathologically confirmed. For R1 (junior radiologist) sensitivity, specificity, PPV, NPV and accuracy for the detection of MSBTs via standard MRI were 52 % [95 % CI: 34 %-70 %] (15/29), 94 % [95 % CI: 89 %-100 %] (65/69), 79 % [95 % CI: 61 %-97 %] (15/19), 82 % [95 % CI: 74 %-91 %] (65/79) and 82 % [95 % CI: 74 %-89 %] (80/98), respectively. For R2 (senior radiologist) they were 76 % [95 % CI: 60 %-91 %] (22/29), 96 % [95 % CI: 91-100 %] (66/69), 88 % [95 % CI: 75 %-100 %] (22/25), 90 % [95 % CI: 84 %-97 %] (66/73) and 90 % [95 % CI: 84 %-96 %] (88/98), respectively. Adding DWI they were 72 % [95 % CI: 56 %-89 %] (21/29), 91 % [95 % CI: 85 %-98 %] (63/69), 78 % [95 % CI: 62 %-94 %] (21/27), 89 % [95 % CI: 81 %-96 %] (63/71) and 87 % [95 % CI: 80 %-94 %] (85/98) for R1 and 79 % [95 % CI: 65 %-94 %] (23/29), 97 % [95 % CI: 93 %-100 %] (67/69), 92 % [95 % CI: 81 %-100 %] (23/25), 92 % [95 % CI: 86 %-98 %] (67/73) and 92 % [95 % CI: 86 %-97 %] (90/98) for R2. Sensitivities for tumour detection were higher after adding DWI to standard MRI, although only for R1 was this significant (P?=?0.03). Adding DWI to standard + gadolinium-enhanced MRI did not significantly increase MR performance.

Conclusion

DWI improves MSBT detection via MR-enterography compared to standard unenhanced MR-enterography, especially for unexperienced readers.

Key Points

? MR-enterography is accurate for the detection of mesenteric small-bowel tumours. ? Diffusion-weighted sequencing helps inexperienced readers detect small-bowel tumours with MR-enterography. ? Diffusion-weighted sequencing adds value to standard MR-enterography when gadolinium is contraindicated.     

Diagnostic accuracy of 18F-FDG PET/CT for assessing response to radiofrequency ablation treatment in lung metastases: a multicentre prospective study

Purpose

To assess diagnostic accuracy of ¹⁸F-FDG PET/CT at 3 months for the detection of local recurrence after radiofrequency ablation (RFA) of lung metastases.

Methods

The PET/CT scan at 3 months was compared with a baseline PET/CT scan from a maximum of 2 months before RFA, with the reference standard as recurrence diagnosed by CT during a 12-month follow-up. Local recurrence was diagnosed on the PET/CT scan if lesional uptake was greater than the mediastinal background. Maximum standardized uptake values (SUVmax) were recorded. ROC curve analysis for SUVmax was performed. Overall survival (OS) and time to local relapse were computed from the date of RFA using the Kaplan-Meier method (www.clinicaltrials.gov: NCT 00382252).

Results

Between 2005 and 2009, 89 patients (mean age 65 years) underwent RFA for 115 lung metastases (mean size 16.2 ± 6.9 mm). The median SUVmax before RFA was 5.8?±?4. PET/CT at 3 months and the reference standard were available in 77 patients and 100 lesions. Accuracy was 66.00 % (95 % CI 55.85–75.18 %), sensitivity 90.91 % (95 % CI 58.72–99.77 %), specificity 62.92 % (95 % CI 52.03–72.93 %), PPV 23.26 % (95 % CI 11.76–38.63 %), and NPV 98.25 % (95 % CI 90.61–99.96 %). One-year OS was 94.2 % (95 % CI 86.6–97.5 %) and the probability of being free of local recurrence 1 year after RFA was 84.6 % (95 % CI 75.0–90.8 %).

Conclusion

The specificity of PET/CT at 3 months is low because of persistent inflammation, especially when the lesion is close to the pleura. This technique is useful for its negative predictive value, but positive findings need to be confirmed by histology before new treatment is planned.     

Contrast enhanced ultrasound in the detection of liver metastases: a prospective multi-centre dose testing study using a perfluorobutane microbubble contrast agent (NC100100)

Objective

To conduct a dose testing analysis of perfluorobutane microbubble (NC100100) contrast-enhanced ultrasound (CEUS) to determine the optimal dose for detection of liver metastases in patients with extra-hepatic primary malignancy.

Methods

157 patients were investigated with conventional US and CEUS. CEUS was performed following intravenous administration of perfluorobutane microbubbles (using one dose of either 0.008, 0.08, 0.12 or 0.36 μL/kg body weight). Three blinded off-site readers recorded the number and locations of metastatic lesions detected by US and CEUS. Contrast enhanced CT and MRI were used as the “Standard Of Reference” (SOR). Sensitivity, specificity and accuracy of liver metastasis detection with US versus CEUS, for each dose group were obtained. Dose group analysis was performed using the Chi-square test.

Results

165 metastases were present in 92 patients who each had 1–7 lesions present on the SOR. Sensitivity of US versus CEUS (for all doses combined) was 38% and 67% (p?=?0.0001). The 0.12 dose group with CEUS (78%) had significantly higher sensitivity and accuracy (70%) compared to other dose groups (p?Conclusion The diagnostic performance of CEUS is dose dependent with the 0.12 μL/kg NC100100 dose group showing the greatest sensitivity and accuracy in detection of liver metastases.     

Characterisation of solitary pulmonary lesions combining visual perfusion and quantitative diffusion MR imaging

Objective

To evaluate the diagnostic accuracy of dynamic contrast-enhanced (DCE) magnetic resonance (MR) and diffusion-weighted imaging (DWI) sequences for defining benignity or malignancy of solitary pulmonary lesions (SPL).

Methods

First, 54 consecutive patients with SPL, clinically staged (CT and PET or integrated PET-CT) as N0M0, were included in this prospective study. An additional 3-Tesla MR examination including DCE and DWI was performed 1 day before the surgical procedure. Histopathology of the surgical specimen served as the standard of reference. Subsequently, this functional method of SPL characterisation was validated with a second cohort of 54 patients.

Results

In the feasibility group, 11 benign and 43 malignant SPL were included. Using the combination of conventional MR sequences with visual interpretation of DCE-MR curves resulted in a sensitivity, specificity and accuracy of 100 %, 55 % and 91 %, respectively. These results can be improved by DWI (with a cut-off value of 1.52?×?10^?3 mm²/s for ADC_high) leading to a sensitivity, specificity and accuracy of 98 %, 82 % and 94 %, respectively. In the validation group these results were confirmed.

Conclusion

Visual DCE-MR-based curve interpretation can be used for initial differentiation of benign from malignant SPL, while additional quantitative DWI-based interpretation can further improve the specificity.

Key Points

? Magnetic resonance imaging is increasingly being used to help differentiate lung lesions. ? Solitary pulmonary lesions (SPL) are accurately characterised by combining DCE-MRI and DWI. ? Visual DCE-MRI assessment facilitates the diagnostic throughput in patients with SPL. ? DWI provides additional information in inconclusive DCE-MRI (type B pattern).     

Diagnostic accuracy of two-dimensional shear wave elastography for the non-invasive staging of hepatic fibrosis in chronic hepatitis B: a cohort study with internal validation

Objectives

To determine the accuracy of two-dimensional shear wave elastography (2D-SWE) for noninvasive staging of hepatic fibrosis in chronic hepatitis B (CHB).

Methods

Patients with CHB infection who underwent liver biopsy were consecutively included. Receiver-operating characteristic (ROC) curves were constructed to assess the overall accuracy and identify optimal cutoff values.

Results

Three hundred three patients were analysed. The diagnostic performance characteristics were determined for the first 202 patients (the index cohort) and were validated on the next 101 patients (validation cohort). The areas under the ROC curves for significant fibrosis, severe fibrosis and cirrhosis were all greater than 0.90 and did not differ significantly between the index and validation cohorts. Using the cutoff values generated from the index cohort, the validation cohort 2D-SWE had negative predictive values of 82.6 % (95 % confidence interval [CI]: 68.4 %???92.3 %) for significant fibrosis, 95.1 % (95 % CI: 86.3 %???99.0 %) for severe fibrosis and 97.4 % (95 % CI: 90.8 %???99.7 %) for cirrhosis. The positive predictive values were 83.6 % (95 % CI: 71.2 %???92.2 %), 65.0 % (95 % CI: 48.1???79.5 %) and 60.0 % (95 % CI: 38.7 %???78.9 %), respectively.

Conclusion

The 2D-SWE showed good diagnostic accuracy in staging liver fibrosis in patients with CHB infection and assisted in excluding liver fibrosis and cirrhosis.

Key Points

? Two-dimensional shear wave elastography showed good diagnostic accuracy in assessing liver fibrosis. ? Diagnostic performance did not differ significantly between the index and validation cohorts. ? Two-dimensional shear wave elastography assisted in excluding liver fibrosis and cirrhosis.     

Effect of b value and pre-admission of contrast on diagnostic accuracy of 1.5-T breast DWI: a systematic review and meta-analysis

Objectives

To evaluate the effect of the choice of b values and prior use of contrast medium on apparent diffusion coefficients (ADCs) of breast lesions derived from diffusion-weighted imaging (DWI), and on the discrimination between benign and malignant lesions.

Methods

A literature search of relevant DWI studies was performed. The accuracy of DWI to characterize lesions by using b value ≤600 s/mm² and b value >600 s/mm² was presented as pooled sensitivity and specificity, and the ADC was calculated for both groups. Lesions were pooled as pre- or post-contrast DWI.

Results

Of 198 articles, 26 met the inclusion criteria. Median ADCs were significantly higher (13.2–35.1 %, p?b values ≤600 s/mm² compared to >600 s/mm². The sensitivity in both groups was similar (91 % and 89 %, p?=?0.495) as well as the specificity (75 % and 84 %, p?=?0.237). Contrast medium had no significant effects on the ADCs (p?≥?0.08). The differentiation between benign and malignant lesions was optimal (58.4 %) for the combination of b?=?0 and 1,000 s/mm².

Conclusions

The wide variety of b value combinations applied in different studies significantly affects the ADC of breast lesions and confounds quantitative DWI. If only a couple of b values are used, those of b?=?0 and 1,000 s/mm² are recommended for the best improvement of differentiating between benign and malignant lesions.

Key Points

? The choice of b values significantly affects the ADC of breast lesions. ? Sensitivity and specificity are not affected by the choice of b values. ? b values 0 and 1,000 s/mm ² are recommended for optimal differentiation between benign and malignant lesions. ? Contrast medium prior to DWI does not significantly affect the ADC.     

Correlation between therapy response assessment using FDG PET/CT and histopathologic tumor regression grade in hepatic metastasis of colorectal carcinoma after neoadjuvant therapy

Purpose

To evaluate the correlation between change in FDG uptake before and after chemotherapy in hepatic metastases of colorectal carcinoma (HCRC) and a histopathologic tumor regression grade (TRG).

Methods

In patients with HCRC, PET/CT data prior to hepatic surgery were retrospectively analyzed under an IRB waiver. The maximum standard uptake value (SUV_max) was measured before and after chemotherapy. The relative change of FDG activity in the identified lesions was calculated (dSUV). Histopathological specimens of resected metastases were graded on a 5-score TRG scale. A TRG of 1–3 was rated as a responding to therapy, whereas TRG 4–5 were regarded as non-responding lesions.

Results

31 lesions were identified in 23 patients. Mean SUV_max before and after therapy was 6.9 ± 3.7 and 3.5 ± 1.8, respectively. The area under the receiver operator characteristic curve revealed a conclusive correlation between TRG and dSUV (AUC 0.773; 95 % confidence interval 0.599–0.946) with a cut off at 41 % decrease in FDG activity yielding a sensitivity and specificity of 72 and 75 %, respectively.

Conclusion

A relative change in FDG activity (dSUV) of more than 41 % decrease correlated significantly with histopathological tumor regression and might be a prognostic tool for response to chemotherapy in HCRC.     

Suspected invasive placenta: evaluation with magnetic resonance imaging

Purpose

To determine the utility of magnetic resonance imaging (MRI) in diagnosing invasive placenta (IP).

Materials and methods

MRI findings in 32 women with suspected IP were evaluated independently by four readers. Interobserver agreement was calculated with kappa (κ) statistics. Associations between MRI findings and IP were assessed by univariate and multivariate analyses. Sensitivity, specificity and accuracy of MRI for the diagnosis of IP were estimated.

Results

Sixteen women (16/32; 50 %) had confirmed IP. Interobserver correlation for the diagnosis of IP was fair (κ?=?0.40). Univariate analysis revealed that thinning or focal defect of the uteroplacental interface (P?P?=?0.0006; OR?=?64.99).

Conclusion

MR imaging has 84 % sensitivity [95 % CI: 75–94 %] and 80 % specificity [95 % CI: 66–93 %] for the diagnosis of IP. Thinning or focal defect of the uteroplacental interface is the most discriminating independent MR variable in differentiating between normal placenta and IP.

Key points

? MR imaging has acceptable degrees of accuracy to diagnose invasive placenta. ? Focal uteroplacental interface defect is the best finding to diagnose invasive placenta. ? Focal uteroplacental interface defect is the single independent predictor of invasive placenta.     

Accuracy of CT angiography in the diagnosis of acute gastrointestinal bleeding: systematic review and meta-analysis

Objective

To assess the diagnostic accuracy of computed tomography (CT) angiography in the evaluation of patients with an episode of acute gastrointestinal haemorrhage.

Methods

Systematic review and meta-analysis to estimate pooled accuracy indices. A bivariate random effects model was adjusted to obtain a summary receiver-operating characteristic (sROC) curve and the corresponding area under the curve (AUC).

Results

Twenty-two studies were included and provided data on 672 patients (range of age 5–74) with a mean age of 65 years. The overall sensitivity of CT angiography for detecting active acute GI haemorrhage was 85.2 % (95 % CI 75.5 % to 91.5 %). The overall specificity of CT angiography was 92.1 % (95 % CI 76.7 % to 97.7 %). The likelihood ratios for positive and negative test results were 10.8 (95 % CI 3.4 to 34.4) and 0.16 (95 % CI 0.1 to 0.27) respectively, with an AUC of 0.935 (95 % CI 0.693 to 0.989). The sources of heterogeneity explored had no significant impact on diagnostic performance.

Conclusions

CT shows high diagnostic accuracy and is an excellent diagnostic tool for detection and localising of intestinal bleeding sites. It is highly available, provides fast detection and localisation of the bleeding site, and is minimally invasive.

Key Points

? CT angiography is increasingly used for investigating severe gastrointestinal bleeding. ? This systematic review and meta-analysis updates previous ones. ? In patients with massive gastrointestinal bleeding, CT angiography/MDCT detects bleeding accurately. ? CT angiography is useful in locating the bleeding site and determining appropriate treatment.     

The usefulness of diffusion-weighted/fluid-attenuated inversion recovery imaging in the diagnostics and timing of lacunar and nonlacunar stroke

Introduction

The DWI/FLAIR mismatch is a potential radiological marker for the timing of stroke onset. The aim of the study was to assess if the DWI/FLAIR mismatch can help to identify patients with both lacunar and nonlacunar acute ischemic stroke within 4.5 h of onset.

Methods

A retrospective study was performed in which the authors analysed data from 86 ischemic lacunar and nonlacunar stroke patients with a known time of symptom onset, imaged within the first 24 h from stroke onset (36 patients <4.5 h, 14 patients 4.5–6 h, 15 patients 6–12 h, and 21 patients 12–24 h). Patients underwent the admission CT and MR scan. The presence of lesions was assessed in correlation with the duration of the stroke.

Results

The time from stroke onset to neuroimaging was significantly shorter in patients with an ischemic lesion visible only in the DWI (mean 2.78 h, n?=?24) as compared to patients with signs of ischemia also in other modalities (mean 8.6 h, n?=?62) (p?=?0.0001, Kruskal–Wallis ANOVA). The DWI/FLAIR mismatch was characterised by a global sensitivity of 58 %, specificity 94 %, PPV 87.5 %, and NPV 76 % in identifying patients in the 4.5 h thrombolysis time window. For lacunar strokes (n?=?20), these parameters were as follows: sensitivity 50 %, specificity 92.8 %, PPV 75 %, and NPV 81.2 %.

Conclusions

The presence of acute ischemic lesions only in DWI can help to identify both lacunar and nonlacunar stroke patients who are in the 4.5 h time window for intravenous thrombolysis with high specificity.