Sichere Diagnostik zystischer Nierenläsionen

Clinical/methodical issue

Cystic renal lesions are commonly seen during routine ultrasound examinations of the abdomen.

Standard radiological methods

Some cystic renal lesions cannot be sufficiently characterized using native ultrasound. In these cases additional imaging might be necessary.

Methodical innovations

Contrast-enhanced ultrasound (CEUS) is a reliable imaging modality to characterize cystic renal lesions. Contrast enhancement of septations and the cystic wall are visualized in high resolution. This information helps to categorize the cystic renal lesions applying the CEUS Bosniak classification. This classification helps to estimate the probability of a malignant etiology of cystic renal lesions.

Performance

Using CEUS, cystic renal lesions can be characterized with a high sensitivity and specificity.

Achievements

The advantages of CEUS include that there is no effect on the function of the kidneys or the thyroid gland and no radiation exposure. In some cases, additional cross-sectional imaging is necessary to optimize diagnostic accuracy.

Practical recommendations

CEUS is a helpful imaging modality to characterize cystic renal lesions, to avoid unnecessary follow-ups and to detect malignant cystic renal lesions.

     

Homogeneously enhancing breast lesions on contrast enhanced US: differential diagnosis by conventional and contrast enhanced US findings

Objective

To clarify the details of homogeneously enhancing lesions on contrast-enhanced ultrasonography (CEUS) and also to elucidate whether their differential diagnosis is possible.

Methods

Seventy-three homogeneously enhancing lesions on CEUS were retrospectively selected. Two radiologists first assessed conventional US findings alone in consensus to differentiate malignant vs. benign lesions. Then, qualitative and quantitative CEUS findings were analyzed to determine the useful findings for the differential diagnosis. Determined CEUS findings were applied to the indeterminate lesions based on conventional US findings to see whether CEUS can improve the diagnostic performance.

Results

There were 42 cancers (58 %) out of 73. Sensitivity and specificity using conventional US findings alone were 91 and 55 %, respectively. Among the CEUS findings tested, multivariate analysis revealed only the type 3 enhancement pattern, which indicates a larger enhancing area than the precontrast hypoechoic lesion, was related to malignancy (p < 0.05). By adding this information, however, no improvement was achieved in the diagnostic performance as determined by conventional US findings.

Conclusions

Approximately half of the homogeneously enhancing lesions on CEUS are malignant, and differentiation of malignant from benign lesions may be possible, at least to some extent, by meticulous assessment of the conventional US rather than CEUS findings.

     

A direct comparison of contrast-enhanced ultrasound and dynamic contrast-enhanced magnetic resonance imaging for prostate cancer detection and prediction of aggressiveness

Introduction

Dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and contrast-enhanced ultrasound (CEUS) analyse tissue vascularization. We evaluated if CEUS can provide comparable information as DCE-MRI for the detection of prostate cancer (PCa) and prediction of its aggressiveness.

Material and methods

A post-hoc evaluation of 92 patients was performed. In each patient CEUS and DCE-MRI parameters of the most suspicious lesion identified on MRI were analysed. The predictive values for discrimination between benign lesions, low-/intermediate- and high-grade PCa were evaluated. Results of targeted biopsy served as reference standard (benign lesions, n=51; low- and intermediate-grade PCa [Gleason grade group 1 and 2], n=22; high-grade PCa [≥ Gleason grade group 3], n=19).

Results

In peripheral zone lesions of all tested CEUS parameters only time to peak (TTP_CEUS) showed significant differences between benign lesions and PCa (AUC 0.65). Of all tested DCE-MRI parameters, rate constant (K_ep) was the best discriminator of high-grade PCa in the whole prostate (AUC 0.83) and in peripheral zone lesions (AUC 0.89).

Conclusion

DCE-MRI showed a superior performance for detection of PCa and prediction of its aggressiveness. CEUS and DCE-MRI performed better in peripheral zone lesions than in transition zone lesions.

Key Points

? DCE-MRI gathers information about vascularization and capillary permeability characteristics of tissues. ? DCE-MRI can detect PCa and predict its aggressiveness. ? CEUS also gathers information about vascularization of tissues. ? For detection of PCa and prediction of aggressiveness DCE-MRI performed superiorly. ? Both imaging techniques performed better in peripheral zone lesions.

     

The prevalence and significance of renal perfusion defects in early kidney transplants quantified using 3D contrast enhanced ultrasound (CEUS)

Objectives

Vascular complications are one of the most common causes of early kidney transplant dysfunction. Contrast enhanced ultrasound increases sensitivity to vascular changes. The aim of this study was to assess the prevalence and size of vascular abnormalities in early renal transplants using 3D CEUS and the significance of perfusion defects on renal function.

Methods

Ninety-nine renal transplant patients underwent 3D CEUS after surgery to quantify perfusion defects as percentage total renal volume (TRV). Serum creatinine and estimated glomerular filtration rate (eGFR) were recorded up to 3 months post-surgery.

Results

Twenty participants had focal perfusion defects (0.2–43%TRV). There was a meaningful difference in patients with perfusion defects in eGFR at 1 month (90% CI 2.7–19.2 mL/min/1.73 m²) and 3 months (90% CI 1.9-19.6 mL/min/1.73 m²) and creatinine at 3 months (90% CI -56 – -8 μmol/L) using a predetermined clinical threshold. Perfusion defect size correlated well with both serum creatinine and eGFR at 3 months (R?=?0.80, p?≤?0.000 and 0.58, p?=?0.038). No correlation was seen prior to 3 months.

Conclusions

Perfusion defects in kidney transplants were more common than expected and were highly likely to reduce renal function at 1-3 months, and the size of the defect affected the degree of functional change at 3 months.

Key Points

? Perfusion defects were more common than previously thought. ? Perfusion defects could be quantified using 3D CEUS. ? The presence of even small perfusion defects may affect kidney function. ? Size of perfusion defects correlated with subsequent kidney function at 3 months. ? Potentially useful in informing clinician expectations of kidney function post-surgery.

     

Frequency and characteristics of contralateral breast abnormalities following recall at screening mammography

Purpose

To determine the frequency and characteristics of contralateral, non-recalled breast abnormalities following recall at screening mammography.

Methods

We included a series of 130,338 screening mammograms performed between 1 January 2014 and 1 January 2016. During the 1-year follow-up, clinical data were collected for all recalls. Screening outcome was determined for recalled women with or without evaluation of contralateral breast abnormalities.

Results

Of 3,995 recalls (recall rate 3.1%), 129 women (3.2%) underwent assessment of a contralateral, non-recalled breast abnormality. Most lesions were detected at clinical mammography and/or breast tomosynthesis (101 women, 78.3%). The biopsy rate was similar for recalled lesions and contralateral, non-recalled lesions, but the positive predictive value of biopsy was higher for recalled lesions (p = 0.01). A comparable proportion of the recalled lesions and contralateral, non-recalled lesions were malignant (p = 0.1). The proportion of ductal carcinoma in situ was similar for both groups, as well as invasive cancer characteristics and type of surgical treatment.

Conclusions

About 3% of recalled women underwent evaluation of contralateral, non-recalled breast lesions. Evaluation of the contralateral breast after recall is important as we found that 15.5% of contralateral, non-recalled lesions were malignant. Contralateral cancers and screen-detected cancers show similar characteristics, stage and surgical treatment.

Key Points

? 3% of recalled women underwent evaluation of contralateral, non-recalled lesions ? One out of seven contralateral, non-recalled lesions was malignant ? A contralateral cancer was diagnosed in 0.5% of recalls ? Screen-detected cancers and non-recalled, contralateral cancers showed similar histological characteristics ? Tumour stage and surgical treatment were similar for both groups

     

Malignancy rate of biopsied suspicious bone lesions identified on FDG PET/CT

Purpose

To determine the malignancy rate of bone lesions identified on FDG PET/CT in patients who have undergone CT-guided biopsy because of the suspicion of malignancy.

Methods

This single-centre retrospective study spanned eight consecutive years and included all patients who underwent both FDG PET/CT and CT-guided bone biopsy because of the suspicion of malignancy. The positive predictive value (PPV) for malignancy was calculated, and different patient and imaging characteristics were compared between malignant and benign bone lesions.

Results

Of 102 included patients with bone lesions that all showed FDG uptake exceeding mediastinal uptake, bone biopsy showed a malignant lesion in 91 patients, yielding a PPV for malignancy of 89.2 % (95 % CI 81.7 – 93.9 %). In the 94 patients with bone lesions that showed FDG uptake exceeding liver uptake, bone biopsy showed a malignant lesion in 83 patients, yielding a PPV for malignancy of 88.3 % (95 % CI 80.1 – 93.5 %). Higher age, bone marrow replacement of the lesion seen on CT, expansion of the lesion seen on CT, and presence of multifocal lesions on FDG PET/CT were significantly more frequent in patients with malignant lesions than in those with benign bone lesions (P?=?0.044, P?=?0.009, P?=?0.015, and P?=?0.019, respectively). Furthermore, there was a trend towards a higher incidence of cortical destruction (P?=?0.056) and surrounding soft tissue mass (P?=?0.063) in patients with malignant bone lesions.

Conclusion

The PPV for malignancy of suspicious bone lesions identified on FDG PET/CT is not sufficiently high to justify changes in patient management without histopathological confirmation. Nevertheless, ancillary patient and imaging characteristics may increase the likelihood of a malignant bone lesion.

     

Discrimination between benign and malignant breast lesions using volumetric quantitative dynamic contrast-enhanced MR imaging

Objective

To determine the diagnostic performance of volumetric quantitative dynamic contrast-enhanced MRI (qDCE-MRI) in differentiation between malignant and benign breast lesions.

Methods

DCE-MRI was performed in 124 patients with 136 breast lesions. Quantitative pharmacokinetic parameters K^trans, K_ep, V_e, V_p and semi-quantitative parameters TTP, MaxCon, MaxSlope, AUC were obtained by using a two-compartment extended Tofts model and three-dimensional volume of interest. Morphologic features (lesion size, margin, internal enhancement pattern) and time-signal intensity curve (TIC) type were also assessed. Logistic regression analysis was used to determine predictors of malignancy, followed by receiver operating characteristics (ROC) analysis to evaluate the diagnostic performance.

Results

qDCE parameters (K^trans, K_ep, V_p, TTP, MaxCon, MaxSlope and AUC), morphological parameters and TIC type were significantly different between malignant and benign lesions (P≤0.001). Multivariate logistic regression analyses showed that K^trans, K_ep, MaxSlope, size, margin and TIC type were independent predictors of malignancy. The diagnostic accuracy of logistic models based on qDCE parameters alone, morphological features plus TIC type, and all parameters combined was 94.9%, 89.0%, and 95.6% respectively.

Conclusion

qDCE-MRI can be used to improve diagnostic differentiation between benign and malignant breast lesions in relation to morphology and kinetic analysis.

Key Points

? qDCE-MRI parameters are useful for discriminating between malignant and benign breast lesions.? K ^trans , K _ep and MaxSlope were independent predictors of breast malignancy.? qDCE-MRI has a better diagnostic ability than morphology and kinetic analysis.? qDCE-MRI can be used to improve the diagnostic accuracy of breast malignancy.

     

Intravoxel incoherent motion MR imaging for breast lesions: comparison and correlation with pharmacokinetic evaluation from dynamic contrast-enhanced MR imaging

Objectives

To compare diagnostic performance for breast lesions by quantitative parameters derived from intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and to explore whether correlations exist between these parameters.

Methods

IVIM and DCE MRI were performed on a 1.5-T MRI scanner in patients with suspicious breast lesions. Thirty-six breast cancers and 23 benign lesions were included in the study. Quantitative parameters from IVIM (D, f and D*) and DCE MRI (K^trans, K_ep, V_e and V_p) were calculated and compared between malignant and benign lesions. Spearman correlation test was used to evaluate correlations between them.

Results

D, f, D* from IVIM and K^trans, K_ep, V_p from DCE MRI were statistically different between breast cancers and benign lesions (p?<?0.05, respectively) and D demonstrated the largest area under the receiver-operating characteristic curve (AUC?=?0.917) and had the highest specificity (83 %). The f value was moderately statistically correlated with V_p (r?=?0.692) and had a poor correlation with K^trans (r?=?0.456).

Conclusions

IVIM MRI is useful in the differentiation of breast lesions. Significant correlations were found between perfusion-related parameters from IVIM and DCE MRI. IVIM may be a useful adjunctive tool to standard MRI in diagnosing breast cancer.

Key Points

? IVIM provided diffusion as well as perfusion information ? IVIM could help differential diagnosis of breast lesions ? Correlations were found between perfusion-related parameters from IVIM and DCE MRI

     

Shear wave elastography of focal salivary gland lesions: preliminary experience in a routine head and neck US clinic

Objectives

To evaluate shear wave elastography (SWE) for focal lesions in major salivary glands.

Methods

Sixty lesions (49 parotid, 11 submandibular) undergoing routine ultrasound (grey scale and Doppler) also underwent SWE before US-guided needle aspiration for cytology. Quantitative indices of the shear elastic modulus (stiffness) were compared with cytological results.

Results

Fifty-five lesions were benign (21 pleomorphic adenomas, 18 Warthin’s tumours; 16 others) and 5 malignant (2 mucoepidermoid carcinomas, 1 myoepithelial carcinoma, 1 B-cell lymphoma, 1 nodal metastasis). Shear modulus of benign lesions, median 18.3 kPa, overlapped appreciably with malignant lesions, median 13.5 kPa. However, 2 mucoepidermoid carcinomas had the highest stiffness values (81.9 kPa, 132.0 kPa). Stiffness of pleomorphic adenomas (median 22.5 kPa) was higher than Warthin’s tumours (16.9 kPa) (P?=?0.05 Mann–Whitney U-test). The standard deviation of stiffness values within a lesion, used as an indicator of spatial heterogeneity, was highest in mucoepidermoid cancers (median 44.2 kPa), followed by pleomorphic adenomas (median 12.4 kPa) and remaining lesions (medians 1.4–10.3 kPa).

Conclusion

This study shows a degree of clustering of SWE indices according to pathology although it appears that SWE has suboptimal performance for ruling out malignancy, thus limiting its use in routine practice.

Key Points

? Shear wave elastography is a feasible technique for focal salivary gland lesions.? Elastographic artefacts aggravated by the regional anatomy may hinder this technique.? Elastographic indices vary according to pathology but there is appreciable overlap.? Overlapping indices for malignant and benign lesions limit its utility.? Pleomorphic adenomas have higher elasticity indices, i.e. are stiffer, than Warthin’s tumours.

     

Malignancy rates and diagnostic performance of the Bosniak classification for the diagnosis of cystic renal lesions in computed tomography – a systematic review and meta-analysis

Objective

To systematically review the literature on the Bosniak classification system in CT to determine its diagnostic performance to diagnose malignant cystic lesions and the prevalence of malignancy in Bosniak categories.

Methods

A predefined database search was performed from 1 January 1986 to 18 January 2016. Two independent reviewers extracted data on malignancy rates in Bosniak categories and several covariates using predefined criteria. Study quality was assessed using QUADAS-2. Meta-analysis included data pooling, subgroup analyses, meta-regression and investigation of publication bias.

Results

A total of 35 studies, which included 2,578 lesions, were investigated. Data on observer experience, inter-observer variation and technical CT standards were insufficiently reported. The pooled rate of malignancy increased from Bosniak I (3.2 %, 95 % CI 0–6.8, I²?=?5 %) to Bosniak II (6 %, 95 % CI 2.7–9.3, I²?=?32 %), IIF (6.7 %, 95 % CI 5–8.4, I²?=?0 %), III (55.1 %, 95 % CI 45.7–64.5, I²?=?89 %) and IV (91 %, 95 % CI 87.7–94.2, I²?=?36). Several study design-related influences on malignancy rates and subsequent diagnostic performance indices were identified.

Conclusion

The Bosniak classification is an accurate tool with which to stratify the risk of malignancy in renal cystic lesions.

Key points

? The Bosniak classification can accurately rule out malignancy.? Specificity remains moderate at 74?% (95?% CI 64–82).? Follow-up examinations should be considered in Bosniak IIF and Bosniak II cysts.? Data on the influence of reader experience and inter-reader variability are insufficient.? Technical CT standards and publication year did not influence diagnostic performance.

     

Proton density fat fraction (PDFF) MRI for differentiation of benign and malignant vertebral lesions

Objectives

To investigate whether proton density fat fraction (PDFF) measurements using a six-echo modified Dixon sequence can help to differentiate between benign and malignant vertebral bone marrow lesions.

Methods

Sixty-six patients were prospectively enrolled in our study. In addition to conventional MRI at 3.0-Tesla including at least sagittal T2-weighted/spectral attenuated inversion recovery and T1-weighted sequences, all patients underwent a sagittal six-echo modified Dixon sequence of the spine. The mean PDFF was calculated using regions of interest and compared between vertebral lesions. A cut-off value of 6.40% in PDFF was determined by receiver operating characteristic curves and used to differentiate between malignant (< 6.40%) and benign (≥ 6.40%) vertebral lesions.

Results

There were 77 benign and 44 malignant lesions. The PDFF of malignant lesions was statistically significant lower in comparison with benign lesions (p < 0.001) and normal vertebral bone marrow (p < 0.001). The areas under the curves (AUC) were 0.97 for differentiating benign from malignant lesions (p < 0.001) and 0.95 for differentiating acute vertebral fractures from malignant lesions (p < 0.001). This yielded a diagnostic accuracy of 96% in the differentiation of both benign lesions and acute vertebral fractures from malignancy.

Conclusion

PDFF derived from six-echo modified Dixon allows for differentiation between benign and malignant vertebral lesions with a high diagnostic accuracy.

Key Points

? Establishing a diagnosis of indeterminate vertebral lesions is a common clinical problem? Benign bone marrow processes may mimic the signal alterations observed in malignancy? PDFF differentiates between benign and malignant lesions with a high diagnostic accuracy? PDFF of non-neoplastic vertebral lesions is significantly higher than that of malignancy? PDFF from six-echo modified Dixon may help avoid potentially harmful bone biopsy

     

Whole-body ultra-low dose CT using spectral shaping for detection of osteolytic lesion in multiple myeloma

Objectives

The aim of this study was to investigate the radiation dose and image quality of a whole-body low-dose CT (WBLDCT) using spectral shaping at 100 kV (Sn 100 kV) for the assessment of osteolytic lesions in patients with multiple myeloma.

Methods

Thirty consecutive patients were retrospectively selected, who underwent a WBLDCT on a third-generation dual-source CT (DSCT) (Sn 100 kV, ref. mAs: 130). They were matched with patients, who were examined on a second-generation DSCT with a standard low-dose protocol (100 kV, ref. mAs: 111). Objective and subjective image quality, radiation exposure as well as the frequency of osteolytic lesions were evaluated.

Results

All scans were of diagnostic image quality. Subjective overall image quality was significantly higher in the study group (p = 0.0003). Objective image analysis revealed that signal intensities, signal-to-noise ratio and contrast-to-noise ratio of the bony structures were equal or significantly higher in the control group. There was no significant difference in the frequency of osteolytic lesions (p = 0.259). The median effective dose of the study protocol was significantly lower (1.45 mSv vs. 5.65 mSv; p < 0.0001).

Conclusion

WBLDCT with Sn 100 kV can obtain sufficient image quality for the depiction of osteolytic lesions while reducing the radiation dose by approximately 74%.

Key points

? Spectral shaping using tin filtration is beneficial for whole-body low-dose CT? Sn 100 kV yields sufficient image quality for depiction of osteolytic lesions? Whole-body low-dose CT can be performed with a median dose of 1.5 mSv

     

Renal Angiomyolipoma: Mid- to Long-Term Results Following Embolization with Onyx

Purpose

Percutaneous transcatheter embolization is currently the preferred treatment for ruptured or enlarging renal angiomyolipoma (AML), although the optimum choice of embolic material has not yet been established. We present mid- to long-term outcomes following embolization of AMLs with Onyx.

Materials and Methods

Ten AMLs in seven patients (including two with tuberous sclerosis) were embolized with Onyx. Patients were followed-up clinically, with tumour size and renal function measured pre- and post-procedure.

Results

Mean pre-treatment AML size was 63.4 mm (range 42–100). Mean clinical follow-up was 431.4 days (range 153–986) and imaging follow-up 284.2 days (range 30–741). There was no haemorrhage from treated lesions within the follow-up period. Of patients who had cross-sectional imaging pre- and post-procedure, mean decrease in AML size of 22 mm was seen after Onyx embolization (p = 0.0058, 95 % CI 9.13–34.87). No significant difference between serum creatinine was seen pre- and post-procedure (p = 0.54, 95 % CI 8.63–4.85).

Conclusions

Onyx embolization of renal AMLs is effective in the medium to long term, with theoretical benefits in safety and durability of result.

     

Diffusion-Weighted Imaging-guided MR Spectroscopy in Breast Lesions using Readout-Segmented Echo-Planar Imaging

Purpose

To investigate the feasibility and effectiveness of diffusion-weighted imaging (DWI)-guided magnetic resonance spectroscopy (MRS) using readout-segmented echo-planar imaging (RS-EPI) to characterise breast lesions.

Materials and methods

A total of 258 patients with 258 suspicious breast lesions larger than 1 cm in diameter were examined using DWI-guided, single-voxel MRS with RS-EPI. The mean total choline-containing compound (tCho) signal-to-noise ratio (SNR) and concentration were used for the interpretation of MRS data. T-tests, χ²-tests, receiver operating characteristic (ROC) curve analyses and Pearson correlations were conducted for statistical analysis.

Results

Histologically, 183 lesions were malignant, and 75 lesions were benign. Both the mean tCho SNR and concentration of malignant lesions were higher than those of benign lesions (6.23?±?3.30 AU/mL vs. 1.26?±?1.75 AU/mL and 3.17?±?2.03 mmol/kg vs. 0.86?±?0.83 mmol/kg, respectively; P?<?0.0001). For a tCho SNR of 2.0 AU/mL and a concentration of 1.76 mmol/kg, the corresponding areas under the ROC curves were 0.93 and 0.90, respectively. The mean tCho SNR and concentration negatively correlated with apparent diffusion coefficients calculated from RS-EPI, with correlation coefficients of ?0.54 and ?0.48, respectively.

Conclusion

DWI-guided MRS using RS-EPI is feasible and accurate for characterising breast lesions.

Key Points

? The mean tCho SNR and concentration negatively correlated with ADCs.? DWI-guided MRS using RS-EPI is feasible.? DWI-guided MRS using RS-EPI accurately characterises breast lesions.

     

A simple scoring system for breast MRI interpretation: does it compensate for reader experience?

Purpose

To investigate the impact of a scoring system (Tree) on inter-reader agreement and diagnostic performance in breast MRI reading.

Materials and methods

This IRB-approved, single-centre study included 100 patients with 121 consecutive histopathologically verified lesions (52 malignant, 68 benign). Four breast radiologists with different levels of MRI experience and blinded to histopathology retrospectively evaluated all examinations. Readers independently applied two methods to classify breast lesions: BI-RADS and Tree. BI-RADS provides a reporting lexicon that is empirically translated into likelihoods of malignancy; Tree is a scoring system that results in a diagnostic category. Readings were compared by ROC analysis and kappa statistics.

Results

Inter-reader agreement was substantial to almost perfect (kappa: 0.643–0.896) for Tree and moderate (kappa: 0.455–0.657) for BI-RADS. Diagnostic performance using Tree (AUC: 0.889–0.943) was similar to BI-RADS (AUC: 0.872–0.953). Less experienced radiologists achieved AUC: improvements up to 4.7 % using Tree (P-values: 0.042–0.698); an expert’s performance did not change (P?=?0.526). The least experienced reader improved in specificity using Tree (16 %, P?=?0.001). No further sensitivity and specificity differences were found (P?>?0.1).

Conclusion

The Tree scoring system improves inter-reader agreement and achieves a diagnostic performance similar to that of BI-RADS. Less experienced radiologists, in particular, benefit from Tree.

Key Points

? The Tree scoring system shows high diagnostic accuracy in mass and non-mass lesions.? The Tree scoring system reduces inter-reader variability related to reader experience.? The Tree scoring system improves diagnostic accuracy in non-expert readers.

     

Magnetic resonance imaging of pulmonary nodules: accuracy in a granulomatous disease–endemic region

Objective

To estimate the diagnostic accuracy of signal intensity of the lesion-to-spinal cord ratio (LSR) and apparent diffusion coefficient (ADC) in diffusion-weighted (DW) magnetic resonance imaging of pulmonary nodules suspicious for lung cancer in granulomatous lung disease-endemic regions.

Methods

Forty-nine patients with indeterminate solitary pulmonary nodules detected by chest computed tomography and histopathologically confirmed diagnoses were included in the study. DW images were analysed semiquantitatively by focusing regions of interest on the lesion and spinal cord at the same level (for LSR calculation). ADCs were estimated from ratios of the two image signal intensities. Ratios of T1 and T2 signal intensity between nodules and muscle were calculated for comparison.

Results

Mean ADCs?±?standard deviations for lung cancer and benign lesions were 0.9?±?0.2 and 1.3?±?0.2?×?10^-3 mm²/s, respectively. Mean LSRs were 1.4?±?0.3 for lung cancer and 1?±?0.1 for benign lesions. ADCs and LSRs differed significantly between malignant and benign lesions (P?<?0.001). Mean T2 signal intensity ratios also differed significantly between benign and malignant lesions (0.8?±?0.2 vs. 1.6?±?0.2; P?<?0.05).

Conclusions

DWI can help to differentiate malignant from benign lesions according to ADC and the LSR with good accuracy.

Key Points

? DW imaging can help differentiate malignant from benign pulmonary nodules. ? ADC and LSR signal intensities had only small overlap between malignant and benign pulmonary nodules. ? Mean T2 signal intensity ratios differed significantly between benign and malignant lesions.

     

Prospective 1-year follow-up pilot study of CT-guided microwave ablation in the treatment of bone and soft-tissue malignant tumours

Purpose

The aims of this work were to assess the feasibility, efficacy, short-term outcome and safety of microwave ablation (MWA) in the treatment of malignant musculoskeletal tumours.

Materials and methods

Sixteen bone and soft-tissue malignant tumours were prospectively included and were treated by CT-guided MWA. The percentage and size of necrosis of the lesions were measured by contrast-enhanced MRI before the procedure and after 1, 3, 6 and 12 months. mRECIST criteria were used to assess tumour response. Procedural success was defined as ≥80 % necrosis. Patient pain (as assessed using a numeric visual scale (NVS)) and side effects were noted.

Results

Six osteolytic metastases, five osteoblastic metastases and five soft tissue sarcomas were treated. At 1 month, 40 % were treated completely, the percentage of necrosis was 85?±?30.4 %, and the success rate was 80 %. At 3, 6 and 12 months the success rate was 80 %, 76.9 % and 63.6 %, respectively. At 12 months, four lesions (36.3 %) still had no recurrence. Mean NVS during the procedure was 3.5?±?2.8. One patient had transitory sciatica without neurological deficit that was treated medically.

Conclusion

CT-guided MWA of bone and soft-tissue malignant tumours is efficient, well tolerated and has good short-term anti-cancer effects.

Key Points

? CT-guided MWA is efficient in treating musculoskeletal malignant tumours. ? This prospective pilot study showed MWA induces high percentages of tumour necrosis. ? MWA has good short-term anti-cancer effects. ? MWA has healing potential when lesions can be completely necrosed. ? CT-guided MWA under equimolar mixture of oxygen-nitrous oxide inhalation is well tolerated.

     

Use of the Kwak Thyroid Image Reporting and Data System (K-TIRADS) in differential diagnosis of thyroid nodules: systematic review and meta-analysis

Purpose

The purpose of this systematic literature review was to assess the usefulness of the Thyroid Image Reporting and Data System (K-TIRADS) classification proposed by Kwak for differentiation of thyroid nodules.

Material and methods

Four literature databases were searched for relevant articles through early January 2017. A meta-analysis was performed to calculate pooled sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-) and diagnostic odds ratio (DOR). The area under the curve (AUC) from the pooled receiver operating characteristic (ROC) was used to assess the usefulness of this classification for differentiation of thyroid nodules. Meta-analysis was conducted by using meta-analysis software.

Results

We analysed six publications describing 10,926 nodules. Pooled sensitivity, specificity, LR+, LR-, DOR, and AUC for pooled ROC were 0.983 (95 % CI 0.976–0.989), 0.552 (95 % CI 0.542–0.562), 2.666 (95 % CI 1.692–4.198), 0.05 (95 % CI 0.035–0.072), 51.020 (95 % CI 15.241–170.79) and 0.938, respectively.

Conclusions

Kwak TIRADS has high sensitivity and low specificity. Thus, it is very useful to discard the benign cases and to reduce the number of biopsies.

Key Points

? Routine, adequate standardization of thyroid nodules ultrasound classification is mandatory. ? Kwak TIRADS parameters are accurate for differentiating focal thyroid lesions. ? Kwak TIRADS system is simple to apply. ? Kwak TIRADS system may become a useful diagnostic tool.

     

Quantitative differentiation of benign and malignant mammographic circumscribed masses using intensity histograms

Purpose

To investigate the usefulness of density gradient of mammographic masses for differentiating benign from malignant lesions, particularly circumscribed masses, which are difficult to diagnose by shape.

Materials and methods

Phantom experiments were performed and diagnostic mammography examinations were reviewed. Mammograms of three acrylic resin globes differing in hardness were acquired with/without applied pressure, and density gradients were examined on intensity histograms with standard deviation (SD) as a hardness index. Similar analyses were performed using clinical mammographic examinations of circumscribed mass lesions. The usefulness of SD for differentiating between benign and malignant lesions was investigated by ROC curve analysis and minimum/maximum values of malignant and benign lesions, respectively.

Results

For circumscribed masses (n = 196, benign, n = 176; malignant, n = 20), ROC analysis showed AUC = 0.786, with sensitivity = 70.0 %, specificity = 70.5 %, accuracy = 70.4 %, positive predictive value = 21.1 %, and negative predictive value = 95.4 % at SD = 64.46. Minimum and maximum SD of malignant and benign masses were 39.1 and 241.7, respectively.

Conclusion

On mammography, circumscribed masses can be diagnosed with moderate accuracy using the intensity histogram SD. Masses with SD below the minimum of breast cancer can be roughly diagnosed as clinically benign.

     

Can positron emission mammography help to identify clinically significant breast cancer in women with suspicious calcifications on mammography?

Objective

To evaluate the diagnostic accuracy of positron emission mammography (PEM) for identifying malignant lesions in patients with suspicious microcalcifications detected on mammography.

Methods

A prospective, single-centre study that evaluated 40 patients with suspicious calcifications at mammography and indication for percutaneous or surgical biopsy, with mean age of 56.4 years (range: 28-81 years). Patients who agreed to participate in the study underwent PEM with 18F-fluorodeoxyglucose before the final histological evaluation. PEM findings were compared with mammography and histological findings.

Results

Most calcifications (n?=?34; 85.0 %) were classified as BIRADS 4. On histology, there were 25 (62.5 %) benign and 15 (37.5 %) malignant lesions, including 11 (27.5 %) ductal carcinoma in situ (DCIS) and 4 (10 %) invasive carcinomas. On subjective analysis, PEM was positive in 15 cases (37.5 %) and most of these cases (n?=?14; 93.3 %) were confirmed as malignant on histology. There was one false-positive result, which corresponded to a fibroadenoma, and one false negative, which corresponded to an intermediate-grade DCIS. PEM had a sensitivity of 93.3 %, specificity of 96.0 % and accuracy of 95 %.

Conclusion

PEM was able to identify all invasive carcinomas and high-grade DCIS (nuclear grade 3) in the presented sample, suggesting that this method may be useful for further evaluation of patients with suspected microcalcifications.

Key Points

? Many patients with suspicious microcalcifications at mammography have benign results at biopsy. ? PEM may help to identify invasive carcinomas and high-grade DCIS. ? Management of patients with suspicious calcifications can be improved.