Intraductal papillary mucinous neoplasm of the pancreas: differentiate from chronic pancreatits by MR imaging

Purpose

To evaluate the differentiating factors for intraductal papillary mucinous neoplasm of the pancreas and chronic pancreatitis as determined by MR imaging.

Materials and methods

During a three-year period, we performed MR imaging on 33, consecutive patients with IPMN and on 41 patients with chronic pancreatitis. All IPMNs were confirmed by surgery. Two radiologists retrospectively analyzed the ductal change, the cyst shape, CBD dilatation, lymphadenopathy, and parenchymal change. The sensitivity and specificity were calculated for each MRI findings using the Chi square test. Statistically significant MR findings were further analyzed using multivariate logistic regression analysis. The diagnostic performance was evaluated according to the area under the receiver operating characteristic curve (A_z) using specific MRI findings. Simple κ statistics were used to evaluate the inter-observer reliability.

Results

Statistically specific findings for IPMN compared with those for chronic pancreatitis, were duct dilatation without stricture (specificity = 95.1%, sensitivity = 75.8%, p < 0.0001), bulging ampulla (specificity = 97.6%, sensitivity = 30.3%, p < 0.0001), nodule in a duct (specificity = 100%, sensitivity = 15.2%, p < 0.0004), grape-like cyst shape (specificity = 97.6%, sensitivity = 78.8%, p < 0.0001), and nodule in a cyst (specificity = 100%, sensitivity = 24.2%, p < 0.0001). Statistically specific findings for chronic pancreatitis compared with those for IPMN, were duct dilatation with strictures (specificity = 93.9%, sensitivity = 95.1%, p < 0.0001), the presence of a stone (specificity = 97.0%, sensitivity = 56.1%, p < 0.0001), and a unilocular cyst shape (specificity = 93.9%, sensitivity = 34.1%, p < 0.0004). Duct dilatation without stricture and a grape-like cyst shape were independently associated with the IPMN. Duct dilatation with strictures was independently associated with the chronic pancreatitis. Interobserver agreement was good to excellent for each finding (κ = 0.762–1.000).

Conclusion

Highly specific findings for IPMN include duct dilatation without stricture, bulging ampulla, nodule in a duct, grape-like cyst shape, and nodule in a cyst. MRI is very useful for differentiating IPMN from chronic pancreatitis using these specific findings.     

Clinical usefulness of free-breathing navigator-triggered 3D MRCP in non-cooperative patients: comparison with conventional breath-hold 2D MRCP

Purpose

To assess the clinical usefulness of free-breathing 3D MRCP in non-cooperative patients compared conventional breath-hold 2D MRCP.

Materials and methods

We performed FB navigator-triggered 3D MRCP using prospective acquisition correction and BH 2D MRCP in 48 consecutive, non-cooperative patients among 772 patients. Thirteen patients had malignant obstruction. Two radiologists independently graded the likelihood of a malignant obstruction, the overall image quality, and the visibility of ten, individual anatomic segments of both the biliary and pancreatic duct in each sequence. The area under the ROC curve and the repeated measures analyses of variance with multiple comparisons were used for the comparison. The κ statistics were used for interobserver agreement.

Result

The diagnostic performance for detecting malignancy was significantly higher on FB MRCP (A_z = 0.962) than on either BH SS-RARE (A_z = 0.820, P < 0.0185) or MS-HASTE MRCP (A_z = 0.816, P < 0.0067). Interobserver agreement was excellent for FB MRCP (κ = 0.889) and fair for both BH SS-RARE (κ = 0.578) and MS-HASTE MRCP (κ = 0.49). FB MRCP had a significantly higher technical quality than BH MRCP (P < 0.001). FB MRCP was seen to have statistically better visibility of peripheral IHD, right main IHD, CHD, cystic duct, and CBD than BH MRCP (P < 0.001). FB MRCP and BH SS-RARE MRCP had statistically better visibility of both the left main IHD and pancreatic duct than did BH MS-HASTE MRCP (P < 0.001).

Conclusion

FB 3D MRCP is useful for non-cooperative patients in whom conventional BH 2D methods cannot be used successfully.     

Comparison of three-dimensional negative-contrast CT cholangiopancreatography with three-dimensional MR cholangiopancreatography for the diagnosis of obstructive biliary diseases

Purpose

The purpose of our study was to compare three-dimensional (3D) negative-contrast CT cholangiopancreatography (3D-nCTCP) with 3D MR cholangiopancreatography (3D-MRCP) for the diagnosis of obstructive biliary diseases.

Materials and methods

3D-nCTCP and 3D-MRCP were performed on seventy clinically documented obstructive biliary diseases patients. The accuracy of each technique in determining the location and cause of biliary obstruction was evaluated compared with the final clinical diagnoses.

Results

Both methods achieved 100% of accuracy in the diagnosis of the presence and location of biliary obstruction, and had a similar sensitivity, specificity, accuracy in differentiating benign from malignant biliary obstruction or calculous from noncalculous biliary obstruction (p > 0.05). At 3D-nCTCP, six patients with stones were misinterpreted as cholangitis (N = 2), papillitis (N = 3), or bile duct adenocarcinoma (N = 1); two metastases were mistaken as acute pancreatitis or pancreatic head carcinomas, and one intrahepatic cholangiocarcinoma was misled as bile duct adenoma. At 3D-MRCP, one small stone, one ampullary adenoma, and one intrahepatic cholangiocarcinoma were mistaken as cholangitis, ampullary stone, and intrahepatic bile duct stone, respectively, and three gallbladder carcinomas and another intrahepatic cholangiocarcinoma were misdiagnosed as hilar cholangiocarcinoma (N = 3) or common hepatic duct stone (N = 1); four metastases were mistaken as pancreatic head carcinomas (N = 3) or distal cholangiocarcinoma (N = 1). The overall accuracy in making specific diagnosis of the cause of biliary obstruction was 87.1% for 3D-nCTCP and 84.3% for 3D-MRCP, respectively, (p > 0.05).

Conclusion

3D-nCTCP has the similar effects as 3D-MRCP for the diagnosis of biliary obstruction and, the location and the cause of biliary obstruction. In view of selected cases contraindications for MRI, 3D-nCTCP is a potential substitute.     

Extended staging of oesophageal cancer using FDG-PET - a critical appraisal

Background and aim

Oesophageal cancer (OC) is a highly aggressive tumour with unfavorable prognosis due to early stages metastases. Treatment and survival rates are highly correlated with tumour wall invasion, lymphatic involvement and metastatic spread. Thus, an accurate staging at initial diagnosis is fundamental for optimal management. In the present review article the potential role of the FDG-PET in the staging of OC is discussed.

Methods

A systematic review of all papers published in PubMed until June 2010 was performed.

Results

Endoscopic ultrasound (EUS) is helpful for T and N staging but not for M staging. CT plays a complementary role to EUS in T staging, especially in excluding T4 disease. However, in N staging, CT relies on “size criteria” (<1cm = benign, >1cm = malignant) which reduces its sensitivity and specificity.FDG-PET has been demonstrated to be a very helpful tool in staging and re-staging OC. Most OCs demonstrate high FDG accumulation and are usually well detected with PET. Unfortunately, PET cannot reveal very small lesions due to its limited spatial resolution, therefore limiting the usefulness of PET in T staging. In N staging, an FDG positive node is highly likely to contain disease. However, FDG-PET cannot reliably separate the primary site from closely adjacent nodes.The real and unquestionable additional diagnostic value of FDG-PET in comparison to CT and EUS is in evaluating distant metastases.

Conclusions

It appears reasonable to include FDG PET/CT in the diagnostic algorithm of patients with OC in order to better define the optimal therapeutic approach.     

Age-related changes in normal adult pancreas: MR imaging evaluation

Objective

To investigate age-related changes in normal adult pancreas as identified by magnetic resonance imaging (MRI).

Materials and methods

We examined 115 patients without pancreatic diseases (21–90 years) who underwent upper abdominal MRI to evaluate the normal pancreatic MRI findings related to aging. The parameters examined were the pancreatic anteroposterior (AP) diameter, pancreatic lobulation, pancreatic signal intensity (SI), depiction of the main pancreatic duct (MPD), grade of the visual SI decrease on the opposed-phase T1-weighted images compared with in-phase images, and enhancement effect of the pancreas in the arterial phase of dynamic imaging.

Results

The pancreatic AP diameter significantly reduced (head, p = 0.0172; body, p = 0.0007; tail, p < 0.0001), and lobulation (p < 0.0001) and parenchymal fatty change (p < 0.0001) became more evident with aging. No significant correlation was observed between aging and pancreatic SI, however the SI on the in-phase T1-weighted images tended to decrease with aging. No significant correlation was observed between aging and the depiction of the MPD as well as aging and contrast enhancement.

Conclusion

MRI findings of pancreatic atrophy, lobulation, and fatty degeneration are characteristic changes related to aging, and it is necessary to recognize these changes in the interpretation of abdominal MRI in patients with and without pancreatic disease.     

Imaging findings in phyllodes tumors of the breast

Purpose

To study the radiological appearance and pathological features of breast phyllodes tumors (PTs), and to enhance the recognition of the tumor.

Materials and methods

Clinical and imaging findings were retrospectively reviewed in 24 women with PTs confirmed by surgical pathology. All of the 24 patients had preoperative MRI and sonography, and 10 had preoperative mammography.

Results

The histologic findings were benign, borderline and malignant PTs in 16.7% (4/24), 45.8% (11/24) and 37.5% (9/24) of cases, respectively. The tumor size (p = 0.001), irregular shape on sonographic imaging (p = 0.039), internal non-enhanced septations (p = 0.009), silt-like changes in enhanced images (p = 0.006) and signal changes from T2-weighted to enhanced images on MRI (p = 0.001) correlated significantly with the histologic grade; the BI-RADS category of the MRI could reflect the PT's histologic grade with a correlation coefficient of 0.440 (p = 0.031). If the category BI-RADS ≥4a was considered to be a suspicious malignant lesion, the diagnostic accuracy of mammography, US and MRI would be 70% (7/10), 62.5% (15/24) and 95.8% (23/24), respectively.

Conclusion

The tumor size and several US and MRI findings can be used to help preoperatively determine the histologic grade of breast PTs. When a patient presents with a progressively enlarging, painless breast mass, MRI should be recommended first.     

Utility of chemical shift and diffusion-weighted imaging in characterization of hyperattenuating adrenal lesions at 3.0T

Objective

The purpose of our study was to evaluate the value of chemical shift imaging (CSI) and diffusion weighted imaging (DWI) at 3.0 T MRI in adrenal hyperattenuating lesions.

Methods

Fifty-one hyperattenuating adrenal lesions in 40 patients were evaluated. Signal intensity index (SII), adrenal to spleen ratio (ASR) and apparent diffusion coefficient (ADC) were used as quantitative analysis parameters.

Results

The mean SII, ASR and ADC values were: benign pheochromocytomas (n = 22), 7.04%; 0.96, 1.15 × 10⁻³ mm²/s; lipid-poor adenomas (n = 18), 33.77%, 0.71, 1.07 × 10⁻³ mm²/s; malignant tumors (n = 7), 11.24%; 1.00; 0.92 × 10⁻³mm²/s. There were significant differences between the lipid-poor adenomas and nonadenomas for SII and ASR, and there were significant differences between the benign and the malignant tumor ADC values. The optimal diagnostic threshold point of SII and ASR for lipid-poor adenomas was 11.96%, 0.83, the sensitivity and specificity were 88.9%, 97.5% and 97%, 83.3%. The optimal diagnostic threshold point of ADC value for benign lesions and malignant tumors was 1.04 × 10⁻³ mm²/s, the sensitivity and specificity were 61.4% and 85.7%.

Conclusion

Quantitative analysis of chemical shift MRI and DWI can help to characterize the hyperattenuating adrenal lesions, especially in differentiatiation between the lipid-poor adenomas, the benign pheochromocytomas, and the malignant tumors.     

Assessment of acute cholangitis by MR imaging

Purpose

The purpose of this study is to assess the common MRI findings of acute cholangitis compared with those of non-acute cholangitis.

Materials and methods

During a 31-month period, we performed MRCP and contrast-enhanced MRI on 173 patients with biliary abnormalities including duct dilatation or stricture. The causes of the biliary abnormalities included biliary stone disease (n = 85), cholangiocarcinoma (n = 47), periampullary cancer (n = 20), GB cancer (n = 4), and others (n = 17). Among 173 patients, 66 consecutive patients were confirmed with acute cholangitis diagnosed according to the Tokyo guideline, and 107 patients were confirmed as having non-acute cholangitis. Two radiologists retrospectively and independently accessed the MR findings, including the cause of biliary abnormality, increased periductal signal intensity on T2-weighted images, the transient periductal signal difference, and the presence of abscess, thrombosis, and ragged duct. They also measured the dilated duct and the thickened wall. The Student t-test and the Pearson chi-square were used. The κ statistics were used to determine interobserver agreement. Logistic regression was used to identify the MR findings that predicted acute cholangitis.

Results

MRI correctly accessed the cause of biliary abnormality in 163 patients (94%). The statistically common findings for acute cholangitis were as follows: increased periductal signal intensity on T2-weighted imaging (n = 26, 39%, p < 0.05); transient periductal signal difference (n = 31, 47%, p < 0.05); abscess (n = 18, 27%, p < 0.05); thrombosis (n = 12, 18%, p < 0.05); and ragged duct (n = 11, 17%, p < 0.05). Interobserver agreement was good to excellent for each finding (κ = 0.74–0.97). The wall thickness showed a statistically significant difference between the acute cholangitis and the non-acute cholangitis group (2.65 mm:2.32 mm, p < 0.05), however, there was no significant difference in duct dilatation in the two groups. The periductal transient attenuation difference was an independent predictor of acute cholangitis (Exp (B) = 6.389, p = 0.018).

Conclusion

MRI accurately assesses the cause of biliary abnormality in patients with cholangitis. Using statistically common MR findings for acute cholangitis, MR imaging is very successful in predicting acute cholangitis.     

Autoimmune pancreatitis: Assessment of the enhanced duct sign on multiphase contrast-enhanced computed tomography

Purpose

To assess the usefulness of the computed tomography (CT) finding of main pancreatic duct (MPD) wall enhancement, termed the “enhanced duct sign”, for diagnosis of autoimmune pancreatitis (AIP) in comparison with diagnosis of pancreatic carcinoma and chronic pancreatitis.

Materials and methods

Two radiologists independently evaluated the presence or absence of the enhanced duct sign on multiphase contrast-enhanced CT in patients with AIP (n = 55), pancreatic carcinoma (n = 50), and chronic pancreatitis (n = 50). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of AIP were calculated. In patients demonstrating the enhanced duct sign, additional findings were evaluated by consensus.

Results

The enhanced duct sign was more frequently observed in patients with AIP (37/55, 67%) than in patients with pancreatic carcinoma (5/50, 10%) or chronic pancreatitis (0/50, 0%) (P < 0.05). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the finding were 0.67, 0.95, 0.85, 0.88, and 0.84, respectively. In AIP, the lumen within the enhanced duct was completely or partially invisible in 29 of 37 (78%) patients, and the enhanced duct was observed within the affected pancreatic parenchyma in 35 of 37 (95%) patients. In pancreatic carcinoma, the lumen within the enhanced duct was visible in all patients (5/5, 100%), and the enhanced duct was observed downstream of the tumor (5/5, 100%).

Conclusion

The enhanced duct sign is highly specific of AIP.     

Tissue characterization of head and neck lesions using diffusion-weighted MR imaging with SPLICE

Purpose

The purpose of this study was to evaluate the usefulness of diffusion-weighted (DW) MR imaging with split acquisition of fast spin-echo signals (SPLICE) in the tissue characterization of head and neck mass lesions.

Patients and methods

DW MR images of 67 head and neck mass lesions were obtained using SPLICE with b-factors of 0 and 771 s/mm². The lesions were classified into three categories: 16 cysts, 32 benign tumors, and 19 malignant tumors. After ADC maps were constructed for all lesions, ADC values were calculated and compared among the three categories.

Results

No case showed severe image distortion on DW MR imaging with SPLICE, and reliable ADC maps and ADC values were obtained in all cases. The mean ADC value of cysts was 2.41 ± 0.48 × 10⁻³ mm²/s, which was significantly higher than that of benign (1.48 ± 0.62 × 10⁻³ mm²/s) and malignant (1.23 ± 0.45 × 10⁻³ mm²/s) tumors (P < 0.001). However, there was no significant difference between the ADC values of benign and malignant tumors (P = 0.246). When an ADC value of 2.10 × 10⁻³ mm²/s or higher was used as the diagnostic criterion for cysts, the sensitivity, specificity, and accuracy were 94%, 88%, and 90%, respectively.

Conclusion

SPLICE was considered a recommended DW MR imaging technique for the head and neck. Although ADC values were useful in differentiating cysts from tumors, they contributed little in predicting malignancy.     

3D-imaging of the knee with an optimized 3D-FSE-sequence and a 15-channel knee-coil

Objectives

To evaluate the clinical usefulness of an optimized 3D-Fast-Spin-Echo-sequence (3D-SPACE) in combination with a 15-channel knee-coil for 3D-imaging of the knee at 3 T.

Methods

15 volunteers and 50 consecutive patients were examined at 3 T with fat-saturated moderately T2-weighted 3D-SPACE (Voxel-size (VS): 0.6 mm × 0.5 mm × 0.5 mm/acquisition-time (AT) 10:44 min) using a 15-channel knee-coil. Flip angle optimization and radial k-space reordering were applied. Signal- and contrast-to-noise-ratios (SNR, CNR) were compared to non-optimized 3D-SPACE (8-channel knee-coil) and conventional 2D-FSE (VS: 0.4 mm × 0.4 mm × 3 mm/total AT: 12 min). Two radiologists independently rated depiction of internal knee structures and assessed detection and depiction of cartilage and meniscus abnormalities compared to conventional 2D-FSE-sequences. Sensitivity and specificity were calculated for a subgroup with arthroscopy as reference standard. Statistical analysis was performed with paired t-tests, confidence intervals and weighted-κ-coefficients.

Results

SNR and CNR particularly of fluid/cartilage of optimized 3D-SPACE were significantly higher (p < 0.05) than of the non-optimized 3D-sequence and conventional 2D-sequence. Blurring and image inhomogeneity were reduced in the optimized sequence. The thin slice-thickness was beneficial for depiction of problematical anatomical structures such as meniscal roots. 3D-SPACE showed significantly higher diagnostic confidence (p < 0.05) for diagnosis of cartilage lesions of the femoral trochlea. Overall sensitivity and specificity of 3D-SPACE and 2D-FSE for cartilage lesions was 82.3%/80.2% and 79.4%/84.2% and 100%/86.4% and 92.3%/81.8% for meniscus lesions.

Conclusions

Optimized 3D-SPACE provides significantly higher signal and contrast compared to conventional 2D-FSE, particularly for fluid and cartilage, leading to improved diagnostic confidence, particularly in problematic areas, such as the femoral trochlea.     

Role of baseline nodule density and changes in density and nodule features in the discrimination between benign and malignant solid indeterminate pulmonary nodules

Purpose

To retrospectively evaluate whether baseline nodule density or changes in density or nodule features could be used to discriminate between benign and malignant solid indeterminate nodules.

Materials and methods

Solid indeterminate nodules between 50 and 500 mm³ (4.6–9.8 mm) were assessed at 3 and 12 months after baseline lung cancer screening (NELSON study). Nodules were classified based on morphology (spherical or non-spherical), shape (round, polygonal or irregular) and margin (smooth, lobulated, spiculated or irregular). The mean CT density of the nodule was automatically generated in Hounsfield units (HU) by the Lungcare^© software.

Results

From April 2004 to July 2006, 7310 participants underwent baseline screening. In 312 participants 372 solid purely intra-parenchymal nodules were found. Of them, 16 (4%) were malignant. Benign nodules were 82.8 mm³ (5.4 mm) and malignant nodules 274.5 mm³ (8.1 mm) (p = 0.000). Baseline CT density for benign nodules was 42.7 HU and for malignant nodules −2.2 HU (p = ns). The median change in density for benign nodules was −0.1 HU and for malignant nodules 12.8 HU (p < 0.05). Compared to benign nodules, malignant nodules were more often non-spherical, irregular, lobulated or spiculated at baseline, 3-month and 1-year follow-up (p < 0.0001). In the majority of the benign and malignant nodules there was no change in morphology, shape and margin during 1 year of follow-up (p = ns).

Conclusion

Baseline nodule density and changes in nodule features cannot be used to discriminate between benign and malignant solid indeterminate pulmonary nodules, but an increase in density is suggestive for malignancy and requires a shorter follow-up or a biopsy.     

Diagnostic value of dynamic contrast-enhanced MRI for submucosal palatal tumors

Objectives

To evaluate the diagnostic value of dynamic contrast-enhanced MRI (DCE-MRI) for differentiating between benign and malignant tumors in the palate.

Materials and methods

26 patients with submucosal palatal tumors were preoperatively examined using DCE-MRI. Their maximum contrast index (CImax), time of CImax (Tmax), and washout ratios (WR300 and WR600) were determined from contrast index curves. The submucosal palatal tumors were divided into two groups according to their Tmax values: the early enhancement group (Tmax < 300 s) consisted of 9 malignant tumors and 6 benign tumors, while the late enhancement group (Tmax ≥ 300 s) included one malignant tumor and 10 benign tumors. We compared the following DCE-MRI parameters between the benign and malignant tumors: CImax and Tmax in all cases and CImax, Tmax, and the washout ratios in the early enhancement group. In addition, we performed a regression analysis of the relationships between tumor size and DCE-MRI parameters; i.e., CImax, Tmax, and washout ratios, among the malignant salivary gland tumors and pleomorphic adenomas.

Results

In all cases and the early enhancement group, significant differences in Tmax were detected between the benign and malignant tumors (P < 0.001 and P < 0.05, respectively), and the optimal Tmax cutoff value for differentiating between them was found to be 165 s. None of the other parameters displayed significant differences between the benign and malignant tumors. Only the WR600 of the pleomorphic adenomas was significantly correlated with tumor size (R² = 0.92, P < 0.001).

Conclusions

Tmax is a useful parameter for distinguishing between benign and malignant submucosal palatal tumors.     

A dedicated BI-RADS training programme: effect on the inter-observer variation among screening radiologists

Introduction

The Breast Imaging Reporting and Data System (BI-RADS) was introduced in the Dutch breast cancer screening programme to improve communication between medical specialists. Following introduction, a substantial variation in the use of the BI-RADS lexicon for final assessment categories was noted among screening radiologists. We set up a dedicated training programme to reduce this variation. This study evaluates whether this programme was effective.

Materials and methods

Two comparable test sets were read before and after completion of the training programme. Each set contained 30 screening mammograms of referred women selected from screening practice. The sets were read by 25 experienced and 30 new screening radiologists. Cohen's kappa (κ) was used to calculate the inter-observer agreement. The BI-RADS 2003 version was implemented in the screening programme as the BI-RADS 2008 version requires the availability of diagnostic work-up, and this is unavailable.

Results

The inter-observer agreement of all participating radiologists (n = 55) with the expert panel increased from a pre-training κ-value of 0.44 to a post-training κ-value of 0.48 (p = 0.14). The inter-observer agreement of the new screening radiologists (n = 30) with the expert panel increased from κ = 0.41 to κ = 0.50 (p = 0.01), whereas there was no difference in agreement among the 25 experienced radiologists (from κ = 0.48 to κ = 0.46, p = 0.60).

Conclusion

Our training programme in the BI-RADS lexicon resulted in a significant improvement of agreement among new screening radiologists. Overall, the agreement among radiologists was moderate (guidelines Landis and Koch). This is in line with results found in the literature.     

The role of ADC measurement in differential diagnosis of focal hepatic lesions

Purpose

To evaluate the utility of apparent diffusion coefficient (ADC) measurement in characterization of focal solid hepatic lesions and determine the role of ADC values in differentiation of solid benign and solid malignant hepatic lesions.

Materials and methods

Between June 2006 and December 2010, a total of 95 focal solid hepatic lesions in 95 consecutive patients were evaluated by abdominal MRI. Diffusion weighted MRI was performed with b 100, b 600 and b 1000 gradients with ADC measurements. Comparison of mean ADC values between solid benign (focal nodular hyperplasia and other solid benign lesions) and solid malignant lesion (hepatocellular carcinoma, metastasis, and cholangiocarcinoma) groups and between each benign and malignant lesion was done. The ROC analyses were performed in order to determine cut-off ADC values for differentiation of benign and malignant lesion groups at 3 different gradients.

Results

Twenty-six of 95 lesions were benign and 69 were malignant. Mean ADC values of solid benign lesions at b 100, b 600 and b 1000 gradients were 2.25 ± 0.54 × 10⁻³, 1.97 ± 0.64 × 10⁻³ and 1.52 ± 0.47 × 10⁻³ mm²/s, respectively. Mean ADC values of solid malignant lesions at b 100, b 600 and b 1000 gradients were 1.84 ± 0.57 × 10⁻³, 1.37 ± 0.38 × 10⁻³ and 1.08 ± 0.22 × 10⁻³ mm²/s, respectively. The ADC values of solid benign lesions were significantly higher than solid malignant lesions at all 3 gradients (P < 0.05). Differentiation of benign and malignant subtype lesions from each other in their groups did not yield as significant findings as comparing results between benign and malignant lesions.

Conclusion

Although ADC measurements were not helpful for differentiating subtypes of solid benign or solid malignant lesions, ADC measurements at 3 different gradients may be useful in differential diagnosis of benign lesions from malignant ones.     

The application value of contrast-enhanced ultrasound in the differential diagnosis of pancreatic solid-cystic lesions

Objective

To retrospectively determine the accuracy of baseline ultrasound (BUS) and of contrast-enhanced ultrasound (CEUS) in the differential diagnosis of pancreatic solid-cystic lesions.

Methods

Fifty-four pancreatic solid-cystic lesions in 52 patients were examined with BUS and CEUS, two different seniority radiologists read the images independently, Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic value of BUS and CEUS in the diagnosis of benign or malignant pancreatic solid-cystic lesions, the diagnostic consistency between different seniority radiologists was evaluated by Kappa statistics.

Results

Among the 54 lesions, there were pancreatic cyst five cases, pancreatic pseudocyst twenty cases, pancreatic cystadenoma eight cases, pancreatic cystadenocarcinoma seven cases, intraductal papillary mucinous neoplasm of pancreas (IPMN) three cases, pancreatic carcinoma combined liquefied six cases, solid-pseudopallary tumor of pancreas (SPTP) three cases, pancreatic myopericytoma one case, pancreatic lymphangioma one case. After ROC analysis, the areas under the ROC curve (Az) were 0.752 by BUS, 0.928 by CEUS to resident radiologist, and 0.896 by BUS, 0.954 by CEUS to staff radiologist. The correct diagnosis rate of specific disease was 42.6% by BUS, 64.8% by CEUS to staff radiologist (P < 0.05), and 33.3% by BUS, 53.7% by CEUS to resident radiologist (P < 0.05). The interobserver agreement in CEUS is higher than that in BUS, the Kappa value was 0.889 ± 0.062 and 0.428 ± 0.126 respectively.

Conclusion

Compared with BUS, CEUS can significantly enhance the diagnostic rate of pancreatic solid-cystic lesions.     

Characterisation of focal liver lesions with unenhanced and contrast enhanced low MI real time ultrasound: on-site unblinded versus off-site blinded reading

Objective

To compare on-site and blinded off-site reading of baseline ultrasound (US) and contrast enhanced ultrasound (CEUS) for classification and characterisation of focal liver lesions.

Materials and methods

99 patients (57 women and 42 men, age range 18–89 years, mean age: 59 years) with 53 malignant and 46 benign liver lesions were studied with unenhanced US followed by contrast enhanced US after injection of 2.4 ml SonoVue^® (Bracco, Milano, Italy). Image interpretation was performed on-site with clinical information available by consensus of two readers and off-site by two independent blinded readers at two different centers. Comparison of pre and post contrast scans and of the different readers was performed. Reference examinations were histology, intraoperative US, MRI or CT.

Results

Sensitivity for malignancy improved from 81/89/66% (on-site/off-site reader 1/2) before to 100/96/96% post contrast administration (p < 0.05, except for reader 1). Specificity improved from 48/48/54% on baseline US to 89/80/76% on CEUS (p < 0.05). Accuracy for specific lesion diagnosis was 62/59/50% pre and 90/77/72% post contrast (p < 0.05). Classification and characterisation post contrast were mildly inferior for off-site reading. Agreement between on-site and off-site readers of unenhanced scans was fair (κ = 0.29–0.39) while it was good for CEUS (κ = 0.63–0.79).

Conclusions

CEUS improves classification and characterisation of focal liver lesions and interobserver agreement compared to conventional US. Classification and characterisation post contrast were mildly but statistically significantly better for on-site than for off-site reading.     

Experimental model to evaluate in vivo and in vitro cartilage MR imaging by means of histological analyses

Objectives

Implementation of an experimental model to compare cartilage MR imaging by means of histological analyses.

Material and methods

MRI was obtained from 4 patients expecting total knee replacement at 1.5 and/or 3 T prior surgery. The timeframe between pre-op MRI and knee replacement was within two days. Resected cartilage-bone samples were tagged with Ethi^®-pins to reproduce the histological cutting course. Pre-operative scanning at 1.5 T included following parameters for fast low angle shot (FLASH: TR/TE/FA = 33 ms/6 ms/30°, BW = 110 kHz, 120 mm × 120 mm FOV, 256 × 256 matrix, 0.65 mm slice-thickness) and double echo steady state (DESS: TR/TE/FA = 23.7 ms/6.9 ms/40°, BW = 130 kHz, 120 × 120 mm FOV, 256 × 256 matrix, 0.65 mm slice-thickness). At 3 T, scan parameters were: FLASH (TR/TE/FA = 12.2 ms/5.1 ms/10°, BW = 130 kHz, 170 × 170 mm FOV, 320 × 320, 0.5 mm slice-thickness) and DESS (TR/TE/FA = 15.6 ms/4.5 ms/25°, BW = 200 kHz, 135 mm × 150 mm FOV, 288 × 320 matrix, 0.5 mm slice-thickness). Imaging of the specimens was done the same day at 1.5 T. MRI (Noyes) and histological (Mankin) score scales were correlated using the paired t-test. Sensitivity and specificity for the detection of different grades of cartilage degeneration were assessed. Inter-reader and intra-reader reliability was determined using Kappa analysis.

Results

Low correlation (sensitivity, specificity) was found for both sequences in normal to mild Mankin grades. Only moderate to severe changes were diagnosed with higher significance and specificity. The use of higher field-strengths was advantageous for both protocols with sensitivity values ranging from 13.6% to 93.3% (FLASH) and 20.5% to 96.2% (DESS). Kappa values ranged from 0.488 to 0.944.

Conclusions

Correlating MR images with continuous histological slices was feasible by using three-dimensional imaging, multi-planar-reformat and marker pins. The capability of diagnosing early cartilage changes with high accuracy could not be proven for both FLASH and DESS.     

Evaluation of breast lesions by contrast enhanced ultrasound: qualitative and quantitative analysis

Objective

To evaluate and compare the diagnostic performance of qualitative, quantitative and combined analysis for characterization of breast lesions in contrast enhanced ultrasound (CEUS), with histological results used as the reference standard.

Methods

Ninety-one patients with 91 breast lesions BI-RADS 3–5 at US or mammography underwent CEUS. All lesions underwent qualitative and quantitative enhancement evaluation. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic performance of different analytical method for discrimination between benign and malignant breast lesions.

Results

Histopathologic analysis of the 91 lesions revealed 44 benign and 47 malignant. For qualitative analysis, benign and malignant lesions differ significantly in enhancement patterns (p < 0.05). Malignant lesions more often showed heterogeneous and centripetal enhancement, whereas benign lesions mainly showed homogeneous and centrifugal enhancement. The detectable rate of peripheral radial or penetrating vessels was significantly higher in malignant lesions than in benign ones (p < 0.001). For quantitative analysis, malignant lesions showed significantly higher (p = 0.031) and faster enhancement (p = 0.025) than benign ones, and its time to peak was significantly shorter (p = 0.002). The areas under the ROC curve for qualitative, quantitative and combined analysis were 0.910 (A_z1), 0.768 (A_z2) and 0.926(A_z3) respectively. The values of A_z1 and A_z3 were significantly higher than that for A_z2 (p = 0.024 and p = 0.008, respectively). But there was no significant difference between the values of A_z1 and A_z3 (p = 0.625).

Conclusions

The diagnostic performance of qualitative and combined analysis was significantly higher than that for quantitative analysis. Although quantitative analysis has the potential to differentiate benign from malignant lesions, it has not yet improved the final diagnostic accuracy.     

Minor salivary gland tumors in the oral cavity: diagnostic value of dynamic contrast-enhanced MRI

Objective

To evaluate the diagnostic value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for minor salivary gland tumors in the oral cavity.

Materials and methods

Thirty-two patients with minor salivary gland tumors were examined preoperatively using DCE-MRI. Their maximum contrast index (CImax), time of CImax (Tmax), Tpeak; i.e., the time that corresponded to the CImax × 0.90, and washout ratios (WR300 and WR600) were determined from contrast index (CI) curves. We compared these parameters between benign and malignant tumors and among the different histopathological types of minor salivary gland tumors. Then, we categorized the patients’ CI curves into four patterns (gradual increase, rapid increase with high washout ratio, rapid increase with low washout, and flat).

Results

Statistically significant differences in Tmax (P = 0.004) and Tpeak (P = 0.002) were observed between the benign and malignant tumors. Regarding each histopathological tumor type, significant differences in Tmax (P < 0.001), Tpeak (P < 0.001), and WR600 (P = 0.026) were observed between the pleomorphic adenomas and mucoepidermoid carcinomas. It was difficult to distinguish between benign and malignant tumors using our CI curve classification because that two-thirds of the cases were classified into the same type (gradual increase).

Conclusion

The DCE-MRI parameters of minor salivary gland tumors contributed little to their differential diagnosis compared with those for major salivary gland tumors. During the diagnosis of minor salivary gland tumors, Tmax is useful for distinguishing between benign and malignant tumors.