Clinical impact of hyperattenuation of adrenal glands on contrast-enhanced computed tomography of polytraumatised patients

Objective

To evaluate the prognostic value of hyperattenuating adrenal glands on contrast-enhanced CT of polytraumatised patients.

Methods

Two hundred ninety-two patients (195 men and 97 women, mean age 45.3?±?23.3 years) were included in this retrospective study. CT examinations were performed 60 s after intravenous injection of contrast material. Image analysis was performed by two radiologists. Patients were assigned to one of two groups according to the attenuation of the adrenal gland [group 1: adrenal glands ≥ inferior vena cava (IVC); group 2: adrenal glands < IVC].

Results

Eighteen patients (42.2 years?±?24.2) were assigned to group 1 and 274 patients (48.4 years?±?22.4) to group 2. The average adrenal density was 150.8?±?36.1 HU in group 1 and 83.7?±?23.6 HU in group 2 (P?<?0.0001). Eight of the 18 patients in group 1 (44.4 %) and 33 of the 274 patients in group 2 (12.4 %) died during hospitalisation (P?<?0.05). Mean adrenal enhancement was significantly higher in patients who died (101.9?±?40.6 HU) compared with survivors (86.1?±?27.0 HU; P?<?0.001).

Conclusion

Hyperattenuation of adrenal glands is associated with a higher mortality rate in polytraumatised patients and may serve as a predictor of poor clinical outcome.

Key points

? Hyperattenuating adrenal glands can be observed in 6.2 % of polytraumatised patients. ? Hyperattenuating adrenal glands indicate poor clinical outcome in polytraumatised patients. ? In polytraumatised patients, hyperattenuating adrenal glands are associated with a high mortality rate. ? Adrenal enhancement is higher amongst patients who died than amongst survivors.     

What parameters from 18F-FDG PET/CT are useful in evaluation of adrenal lesions?

Purpose

Prior studies have suggested that ¹⁸F-FDG PET/CT can help characterize adrenal lesions and differentiate adrenal metastases from benign lesions. The aim of this study was to assess the value of ¹⁸F-FDG PET/CT for the differentiation of malignant from benign adrenal lesions.

Methods

This retrospective study included 85 patients (47 men and 38 women, age 63.8?±?10.8 years) who had undergone ¹⁸F-FDG PET/CT (60 min after injection 300 – 370 MBq ¹⁸F-FDG; Biograph 64 scanner) for evaluation of 102 nonsecreting adrenal masses. For semiquantitative analysis, the maximum standardized uptake value (SUVmax), adrenal to liver (T/L) SUVmax ratio, mean CT attenuation value and tumour diameter were measured in all lesions and compared with the pathological findings.

Results

Malignant adrenal tumours (68 % of evaluated tumours) had a significantly higher mean SUVmax (13.0?±?7.1 vs. 3.7?±?3.0), a higher T/L SUVmax ratio (4.2?±?2.6 vs. 1.0?±?0.9), a higher CT attenuation value (31.9?±?16. 7 HU vs. 0.2?±?25.8 HU) and a greater diameter (43.6?±?23.7 mm vs. 25.6?±?13.3 mm) than benign lesions. The false-positive findings were tuberculosis and benign phaeochromocytoma. Based on ROC analysis, a T/L SUVmax ratio >1.53, an adrenal SUVmax >5.2, an attenuation value >24 HU and a tumour diameter >30 mm were chosen as the optimal cut-off values for differentiating malignant from benign tumours. The areas under the ROC curves for the selected cut-off values were 0.96, 0.96, 0.88 and 0.77, respectively. A multivariate logistic regression model revealed that the T/L SUVmax ratio was an independent prognostic factor for malignancy (p?25 HU and a tumour diameter >30 mm had no additional individual importance in the diagnosis of malignancy.

Conclusion

Using a T/L SUVmax ratio >1.53 and an adrenal SUVmax >5.2 in ¹⁸F-FDG PET/CT led to high diagnostic sensitivity, specificity and negative predictive value for characterizing adrenal tumours. The diagnostic accuracies of the two parameters were comparable, but T/L SUVmax ratio was an independent predictor of malignancy.     

Dynamic perfusion CT parameters and delayed contrast washout CT in characterization of adrenal tumors: A comparative study

Purpose

The study aims to compare the accuracy of washout and perfusion CT techniques in diagnosis of adrenal tumors.

Dual energy CT in patients with polycystic kidney disease

Objectives

To evaluate the diagnostic efficacy of dual source–dual energy CT (DECT) in the detection of neoplasia in patients with polycystic kidney disease (PKD).

Methods

A total of 21 patients with PKD underwent DECT on a dual source system, using kVp settings of Sn140/100 or 140/80. Colour-coded iodine maps and virtual unenhanced images were used to determine enhancement within cysts and to differentiate haemorrhagic from simple cysts. A cut-off of 15?HU was used as a threshold for malignancy. In patients with malignancy, histopathology was the gold standard; otherwise, patients underwent follow-up imaging for 150–908?days.

Results

On the basis of measured enhancement, 13 enhancing masses were seen in 4 patients (12 renal cell cancers and 1 adenoma); follow-up imaging showed no malignancy in 18 patients. Cysts did not enhance by more than 15?HU, whereas masses showed a mean enhancement of 45 (25–123)?HU. Average radiation exposure was 9.6?mSv for the biphasic protocol and 5.8?mSv for DECT only.

Conclusion

DECT greatly facilitates the detection of malignancy in patients with polycystic kidney disease, at the same time reducing radiation exposure by omission of a true unenhanced phase.

Key Points

? Identification of tumours within polycystic kidneys can be difficult. ? Dual energy computed tomography (DECT) provides two separate sets of images. ? Iodine maps and virtual non-enhanced (VNE) images can then be calculated. ? DECT facilitates screening for potential renal tumours in polycystic kidneys.     

Can single-phase dual-energy CT reliably identify adrenal adenomas?

Purpose

To evaluate whether single-phase dual-energy-CT-based attenuation measurements can reliably differentiate lipid-rich adrenal adenomas from malignant adrenal lesions.

Materials and methods

We retrospectively identified 51 patients with adrenal masses who had undergone contrast-enhanced dual-energy-CT (140/100 or 140/80 kVp). Virtual non-contrast and colour-coded iodine images were generated, allowing for measurement of pre- and post-contrast density on a single-phase acquisition. Adrenal adenoma was diagnosed if density on virtual non-contrast images was ≤10 HU. Clinical follow-up, true non-contrast CT, PET/CT, in- and opposed-phase MRI, and histopathology served as the standard of reference.

Results

Based on the standard of reference, 46/57 (80.7 %) adrenal masses were characterised as adenomas or other benign lesions; 9 malignant lesions were detected. Based on a cutoff value of 10 HU, virtual non-contrast images allowed for correct identification of adrenal adenomas in 33 of 46 (71 %), whereas 13/46 (28 %) adrenal adenomas were lipid poor with a density ≥10 HU. Based on the threshold of 10 HU on the virtual non-contrast images, the sensitivity, specificity, and accuracy for detection of benign adrenal lesions was 73 %, 100 %, and 81 % respectively.

Conclusion

Virtual non-contrast images derived from dual-energy-CT allow for accurate characterisation of lipid-rich adrenal adenomas and can help to avoid additional follow-up imaging.

Key Points

? Adrenal adenomas are a common lesion of the adrenal glands. ? Differentiation of benign adrenal adenomas from malignant adrenal lesions is important. ? Dual-energy based virtual non-contrast images help to evaluate patients with adrenal adenomas.     

Shear-wave elastography in the diagnosis of solid breast masses: what leads to false-negative or false-positive results?

Objective

To investigate the factors that have an effect on false-positive or false-negative shear-wave elastography (SWE) results in solid breast masses.

Methods

From June to December 2012, 222 breast lesions of 199 consecutive women (mean age: 45.3?±?10.1 years; range, 21 to 88 years) who had been scheduled for biopsy or surgical excision were included. Greyscale ultrasound and SWE were performed in all women before biopsy. Final ultrasound assessments and SWE parameters (pattern classification and maximum elasticity) were recorded and compared with histopathology results. Patient and lesion factors in the ‘true’ and ‘false’ groups were compared.

Results

Of the 222 masses, 175 (78.8 %) were benign, and 47 (21.2 %) were malignant. False-positive rates of benign masses were significantly higher than false-negative rates of malignancy in SWE patterns, 36.6 % to 6.4 % (P?<?0.001). Among both benign and malignant masses, factors showing significance among false SWE features were lesion size, breast thickness and lesion depth (all P?<?0.05). All 47 malignant breast masses had SWE images of good quality.

Conclusions

False SWE features were more significantly seen in benign masses. Lesion size, breast thickness and lesion depth have significance in producing false results, and this needs consideration in SWE image acquisition.

Key Points

? Shear-wave elastography (SWE) is widely used during breast imaging ? At SWE, false-positive rates were significantly higher than false-negative rates ? Larger size, breast thickness, depth and fair quality influences false-positive SWE features ? Smaller size, larger breast thickness and depth influences false-negative SWE features     

Breast cancer risk prediction model: a nomogram based on common mammographic screening findings

Objectives

To develop a prediction model for breast cancer based on common mammographic findings on screening mammograms aiming to reduce reader variability in assigning BI-RADS.

Methods

We retrospectively reviewed 352 positive screening mammograms of women participating in the Dutch screening programme (Nijmegen region, 2006–2008). The following mammographic findings were assessed by consensus reading of three expert radiologists: masses and mass density, calcifications, architectural distortion, focal asymmetry and mammographic density, and BI-RADS. Data on age, diagnostic workup and final diagnosis were collected from patient records. Multivariate logistic regression analyses were used to build a breast cancer prediction model, presented as a nomogram.

Results

Breast cancer was diagnosed in 108 cases (31 %). The highest positive predictive value (PPV) was found for spiculated masses (96 %) and the lowest for well-defined masses (10 %). Characteristics included in the nomogram are age, mass, calcifications, architectural distortion and focal asymmetry.

Conclusion

With our nomogram we developed a tool assisting screening radiologists in determining the chance of malignancy based on mammographic findings. We propose cutoff values for assigning BI-RADS in the Dutch programme based on our nomogram, which will need to be validated in future research. These values can easily be adapted for use in other screening programmes.

Key points

? There is substantial reader variability in assigning BI-RADS in mammographic screening. ? There are no strict guidelines linking mammographic findings to BI-RADS categories. ? We developed a model (nomogram) predicting the presence of breast cancer. ? Our nomogram is based on common findings on positive screening mammograms. ? The nomogram aims to assist screening radiologists in assigning BI-RADS categories.     

Adrenal gland volume measurement in septic shock and control patients: a pilot study

Objectives:

To compare adrenal gland volume in septic shock patients and control patients by using semi-automated volumetry.

Methods:

Adrenal gland volume and its inter-observer variability were measured with tomodensitometry using semi-automated software in 104 septic shock patients and in 40 control patients. The volumes of control and septic shock patients were compared and the relationship between volume and outcome in intensive care was studied.

Results:

The mean total volume of both adrenal glands was 7.2?±?2.0 cm³ in control subjects and 13.3?±?4.7 cm³ for total adrenal gland volume in septic shock patients (p?<?0.0001). Measurement reproducibility was excellent with a concordance correlation coefficient value of 0.87. The increasing adrenal gland volume was associated with a higher rate of survival in intensive care.

Conclusion:

The present study reports that with semi-automated software, adrenal gland volume can be measured easily and reproducibly. Adrenal gland volume was found to be nearly double in sepsis compared with control patients. The absence of increased volume during sepsis would appear to be associated with a higher rate of mortality and may represent a prognosis factor which may help the clinician to guide their strategy.     

Diffusion-weighted MRI for distinguishing non-neoplastic cysts from solid masses in the mediastinum: problem-solving in mediastinal masses of indeterminate internal characteristics on CT

Objectives

To evaluate the usefulness of diffusion-weighted (DW) magnetic resonance images for distinguishing non-neoplastic cysts from solid masses of indeterminate internal characteristics on computed tomography (CT) in the mediastinum.

Methods

We enrolled 25 patients with pathologically proved mediastinal masses who underwent both thoracic CT and magnetic resonance imaging (MRI) including diffusion-weighted imaging (DWI). MRI was performed in patients with mediastinal masses of indeterminate internal characteristics on CT. Two thoracic radiologists evaluated the morphological features and quantitatively measured the net enhancement of the masses at CT. They also reviewed MR images including unenhanced T1- and T2-weighted images, gadolinium-enhanced images and DW images.

Results

The enrolled patients had 15 solid masses and ten non-neoplastic cysts. Although the morphological features and the extent of enhancement on CT did not differ significantly between solid and cystic masses in the mediastinum (P?>?0.05), non-neoplastic cysts were distinguishable from solid masses by showing signal suppression on high-b-value DW images or high apparent diffusion coefficient (ADC) values of more than 2.5?×?10^-3 mm²/s (P?<?0.001). ADC values of non-neoplastic cysts (3.67?±?0.87?×?10^-3 mm²/s) were significantly higher than that of solid masses (1.46?±?0.50?×?10^-3 mm²/s) (P?<?0.001).

Conclusions

DWI can help differentiate solid and cystic masses in the mediastinum, even when CT findings are questionable.

Key Points

? Non-invasive diagnosis of non-neoplastic cysts can save surgical biopsy or excision. ? Conventional CT or MRI findings cannot always provide a confident diagnosis. ? Mediastinal masses can be well-characterised with DWI. ? Non-neoplastic mediastinal cysts show significantly higher ADC values than cystic tumours. ? DWI is useful to determine treatment strategy.     

Pulmonary nodules and masses in lung transplant recipients: clinical and CT findings

Objectives

The purpose of this study was to review the clinical and CT findings of pulmonary nodules and masses in lung transplant recipients and to determine distinguishing features among the various aetiologies.

Methods

This retrospective study included 106 lung transplant recipients who had a chest CT performed over a 7-year period in a single institution.

Results

Twenty-four cases of pulmonary nodules and masses were observed on CT. Among the single lesions, three (50 %) were due to infections, one (17 %) to organizing pneumonia, and two (33 %) remained of undetermined origin. Among the multiple lesions, 14 (78 %) were due to infection, three to post-transplant lymphoproliferative disorder (17 %), and one to bronchogenic carcinoma (5 %). The two main microorganisms were P. aeruginosa and Aspergillus spp. Among 12 solid nodules >?1 cm, four (33 %) were due to malignancy: three post-transplant lymphoproliferative disorders (25 %), and one bronchogenic carcinoma (8 %). Among five cavitary nodules four (80 %) were due to aspergillosis.

Conclusion

Infection is the most frequent aetiology of pulmonary nodules and masses in lung transplant recipients, but other causes such as post-transplant lymphoproliferative disorder, bronchogenic carcinoma, or organizing pneumonia should be considered.

Key points

? Pulmonary nodules and masses are frequent in lung transplant recipients. ? Infection is the most frequent aetiology of solitary and multiple pulmonary nodules. ? Differential diagnosis includes post-transplant lymphoproliferative disorder, bronchogenic carcinoma, and organizing pneumonia. ? Clinical and CT findings are often non-specific. ? CT findings may be suggestive of some aetiologies that justify a biopsy.     

Differentiating intraparenchymal hemorrhage from contrast extravasation on post-procedural noncontrast CT scan in acute ischemic stroke patients undergoing endovascular treatment

Introduction

This study aimed to identify the imaging characteristics that can help differentiate intraparenchymal hemorrhage from benign contrast extravasation on post-procedural noncontrast CT scan in acute ischemic stroke patients after endovascular treatment.

Methods

We reviewed the clinical and imaging records of all acute ischemic stroke patients who underwent endovascular treatment in two hospitals over a 3.5-year period. The immediate post-procedural CT scan was evaluated for the presence of hyperdense lesion(s). The average attenuation of the lesion(s) was measured. Intraparenchymal hemorrhage was defined as a persistent hyperdensity visualized on follow-up CT scan, 24 h or greater after the procedure.

Results

Of the 135 patients studied, 74 (55 %) patients had hyperdense lesion(s) on immediate post-procedural CT scan. Follow-up scans confirmed the diagnosis of intraparenchymal hemorrhage in 20 of these 74 patients. A receiver operating characteristic analysis showed that the average attenuation of the most hyperdense lesion can differentiate intraparenchymal hemorrhage from contrast extravasation with an area under the curve of 0.78 (p?=?0.001). An average attenuation of <50 Hounsfield units (HU) in the most visually hyperattenuating hyperdense lesion had 100 % specificity and 56 % sensitivity for identification of contrast extravasations. Petechial hyperdensity was seen in 46/54 (85 %) patients with contrast extravasation versus 9/20 (45 %) patients with intraparenchymal hemorrhage on the immediate post-procedural CT scan (p?Conclusion An average attenuation <50 HU of the most hyperattenuating hyperdense parenchymal lesion on immediate post-procedural CT scan was very specific for differentiating contrast extravasation from intraparenchymal hemorrhage in acute ischemic stroke patients after endovascular treatment.     

MRI-only lesions: application of diffusion-weighted imaging obviates unnecessary MR-guided breast biopsies

Objective

To assess if the application of diffusion-weighted imaging (DWI) obviates unnecessary MR-guided biopsies in suspicious breast lesions visible only on contrast-enhanced MRI (CE-MRI).

Methods

This institutional review board (IRB)-approved, retrospective, single-centre study included 101 patients (mean age, 49.5; SD 13.9 years) who underwent additional DWI at 1.5 T prior to MRI-guided biopsy of 104 lesions classified as suspicious for malignancy and visible on CE-MRI only. An experienced radiologist, blinded to histopathologic and follow-up results, measured apparent diffusion coefficient (ADC) values obtained from DWI. Diagnostic accuracy was investigated using receiver operating characteristics (ROC) analysis.

Results

Histopathology revealed 20 malignant and 84 benign lesions. Lesions were masses in 61 (15 malignant, 24.6 %) and non-masses in 43 cases (five malignant, 11.6 %). Mean ADC values were 1.53?±?0.38?×?10^?3 mm²/s in benign lesions and 1.06?±?0.27?×?10^?3 mm²/s in malignant lesions. ROC analysis revealed exclusively benign lesions if ADC values were greater than 1.58?×?10^?3 mm²/s. As a consequence, 29 false-positive biopsies (34.5 %) could have been avoided without any false-negative findings. Both in mass and in non-mass lesions, rule-in and rule-out criteria were identified using flexible ADC thresholds based on ROC analysis.

Conclusion

Additional application of DWI in breast lesions visible only on MRI can avoid false-positive, MR-guided biopsies. Thus, DWI should be an integral part of breast MRI protocols.

Key Points

? DWI measurements are a fast and helpful technique for improved breast lesion diagnosis ? DWI application in breast lesions visible only on MRI obviates false-positive, MR-guided biopsies ? Flexible ADC thresholds provide rule-in and rule-out criteria for breast lesion malignancy     

Impact of breast mass size on accuracy of ultrasound elastography vs. conventional B-mode ultrasound: a meta-analysis of individual participants

Objectives

To conduct an individual patient data meta-analysis comparing the diagnostic performance of ultrasound elastography (USE) versus B-mode ultrasound (USB) across size ranges of breast masses.

Methods

An extensive literature search of PubMed and other medical/general purpose databases from inception through August 2011 was conducted. Corresponding authors of published studies that reported a direct comparison of the diagnostic performance of USE using the elasticity score versus USB for characterisation of focal breast masses were contacted for their original patient-level data set. Summary diagnostic performance measures were compared for each test within and across three mass size groups (<10 mm, 10–19 mm, and >19 mm).

Results

The patient-level data sets were received from five studies, providing information on 1,412 breast masses. For breast masses <10 mm (n?=?543; 121 malignant), the sensitivity/specificity of USE and USB were 76 %/93 % and 95 %/68 %, respectively. For masses 10–19 mm of size (n?=?528; 247 malignant), sensitivity/specificity of USE and USB were 82 %/90 % and 95 %/67 %, respectively. For masses >19 mm of size (n?=?325; 162 malignant), sensitivity/specificity of USE and USB were 74 %/94 % and 97 %/55 %, respectively.

Conclusion

Regardless of the mass size, USE has higher specificity and lower sensitivity compared to USB in characterising breast masses. The performance of each of these two tests does not vary significantly by mass size.

Key Points

? Ultrasound elastography is increasingly used for breast lesions. ? Its diagnostic performance is not dependent on the size of the mass. ? Ultrasound elastography has higher specificity/lower sensitivity than B-mode ultrasound. ? Elastography is advised when B-mode results are equivocal.     

MR elastography of liver tumours: value of viscoelastic properties for tumour characterisation

Objectives

To assess the value of the viscoelastic parameters in the characterisation of liver tumours at MR elastography.

Patients and methods

Ninety-four patients with liver tumours >1?cm prospectively underwent MR elastography using 50-Hz mechanical waves and a full three-directional motion-sensitive sequence. The model-free viscoelastic parameters (the complex shear modulus and its real and imaginary parts, i.e. the storage and loss moduli) were calculated in 72 lesions after exclusion of cystic, treated or histopathologically undetermined tumours.

Results

We observed higher absolute shear modulus and loss modulus in malignant versus benign tumours (3.38?±?0.26 versus 2.41?±?0.15 kPa, P?P?Conclusions The increased loss modulus is a better discriminator between benign and malignant tumours than the increased storage modulus or absolute value of the shear modulus.

Key Points

? Magnetic Resonance elastography is a new method of assessing the liver. ? Increased loss modulus is an indicator of malignancy in hepatic tumours. ? Loss modulus is a better discriminator than absolute shear modulus values. ? The viscoelastic properties of lesions offer promise for characterising liver tumours.     

Influence of imaging and histological factors on prostate cancer detection and localisation on multiparametric MRI: a prospective study

Objectives

To assess factors influencing prostate cancer detection on multiparametric (T2-weighted, diffusion-weighted, and dynamic contrast-enhanced) MRI.

Methods

One hundred and seventy-five patients who underwent radical prostatectomy were included. Pre-operative MRI performed at 1.5 T (n?=?71) or 3 T (n?=?104), with (n?=?58) or without (n?=?117) an endorectal coil were independently interpreted by two radiologists. A five-point subjective suspicion score (SSS) was assigned to all focal abnormalities (FAs). MR findings were then compared with whole-mount sections.

Results

Readers identified 192–214/362 cancers, with 130–155 false positives. Detection rates for tumours of <0.5 cc (cm³), 0.5–2 cc and >2 cc were 33–45/155 (21–29 %), 15–19/35 (43–54 %) and 8–9/12 (67–75 %) for Gleason ≤6, 17/27 (63 %), 42–45/51 (82–88 %) and 34/35 (97 %) for Gleason 7 and 4/5 (80 %), 13/14 (93 %) and 28/28 (100 %) for Gleason ≥8 cancers respectively. At multivariate analysis, detection rates were influenced by tumour Gleason score, histological volume, histological architecture and location (P?<?0.0001), but neither by field strength nor coils used for imaging. The SSS was a significant predictor of both malignancy of FAs (P?<?0.005) and aggressiveness of tumours (P?<?0.00001).

Conclusions

Detection rates were significantly influenced by tumour characteristics, but neither by field strength nor coils used for imaging. The SSS significantly stratified the risk of malignancy of FAs and aggressiveness of detected tumours.

Key Points

? Prostate cancer volume, Gleason score, architecture and location are MRI predictors of detection. ? Field strength and coils used do not influence the tumour detection rate. ? Multiparametric MRI is accurate for detecting aggressive tumours. ? A subjective suspicion score can stratify the risk of malignancy and tumour aggressiveness.     

Dynamic contrast-enhanced and ultra-high-resolution breast MRI at 7.0 Tesla

Objective

To assess the feasibility of 7-T contrast-enhanced breast MRI in patients with suspicious masses.

Methods

Twenty patients with 23 suspicious breast masses on conventional imaging (mean size 13 mm, range 5–27 mm) were examined at 7 T. The MRI protocol included a dynamic series with injection of 0.1 mmol/kg gadobutrol (seven consecutive 3D T1-weighted gradient echo sequences, resolution 1?×?1?×?2 mm³, temporal resolution 63 s) and ultra-high-resolution imaging (T1-weighted 3D gradient echo sequence, resolution 0.45?×?0.57?×?0.45 mm³). Two observers (R1 and R2) independently judged the examinations on image quality and classified lesions according to BI-RADS. The added value of ultra-high-resolution imaging was assessed.

Results

The image quality was deemed excellent in 1 and 0, good in 10 and 12, sufficient in 8 and 8, and insufficient in 1 and 0 for R1 and R2 respectively. Twenty of the 23 lesions were identified at 7-T MRI by both observers. All histopathologically proven malignant lesions (n?=?19) were identified and classified as BI-RADS-MRI 4 or 5. Ultra-high-resolution imaging increased reader confidence in 88 % (R1) and 59 % (R2) of acquisitions.

Conclusion

The study shows the feasibility of dynamic contrast-enhanced 7-T breast MRI, where all malignant mass lesions were identified by two observers.

Key Points

? Magnetic resonance imaging is important in the evaluation of breast cancer. ? Recently, 7-T MRI has become available. ? The 7-T dynamic contrast-enhanced breast MRI is feasible in patients. ? The 7-T breast examinations are amenable to evaluation according to BI-RADS.     

The impact of CT radiation dose reduction and iterative reconstruction algorithms from four different vendors on coronary calcium scoring

Objectives

To analyse the effects of radiation dose reduction and iterative reconstruction (IR) algorithms on coronary calcium scoring (CCS).

Methods

Fifteen ex vivo human hearts were examined in an anthropomorphic chest phantom using computed tomography (CT) systems from four vendors and examined at four dose levels using unenhanced prospectively ECG-triggered protocols. Tube voltage was 120 kV and tube current differed between protocols. CT data were reconstructed with filtered back projection (FBP) and reduced dose CT data with IR. CCS was quantified with Agatston scores, calcification mass and calcification volume. Differences were analysed with the Friedman test.

Results

Fourteen hearts showed coronary calcifications. Dose reduction with FBP did not significantly change Agatston scores, calcification volumes and calcification masses (P?>?0.05). Maximum differences in Agatston scores were 76, 26, 51 and 161 units, in calcification volume 97, 27, 42 and 162 mm³, and in calcification mass 23, 23, 20 and 48 mg, respectively. IR resulted in a trend towards lower Agatston scores and calcification volumes with significant differences for one vendor (P?Conclusions CCS derived from standard FBP acquisitions was not affected by radiation dose reductions up to 80 %. IR resulted in a trend towards lower Agatston scores and calcification volumes.

Key points

? In this ex vivo study, radiation dose could be reduced by 80 % for coronary calcium scoring ? Iterative reconstruction resulted in a trend towards lower Agatston scores and calcification volumes ? Caution should be taken for coronary calcium scoring with iterative reconstruction     

Assessment of soft tissue tumours of the extremities with diffusion echoplanar MR imaging

Purpose

This study assessed soft tissue tumours of the extremities with diffusion echo-planar magnetic resonance (MR) imaging.

Materials and methods

We carried out a retrospective study of 37 patients (22 male, 15 female; age range 4?C68 years; mean age 41 years) with a soft tissue mass. Diffusion-weighted magnetic resonance (MR) imaging was done using echo-planar imaging (EPI) with b factor of 0.500 and 1,000 mm2/s. The apparent diffusion coefficient (ADC) map was reconstructed with calculation of the ADC values of the mass.

Results

The mean ADC value of the malignant tumours was 1.02±0.03×10^?3mm²/s and that of benign masses 1.54±0.03×10^?3mm²/s. There was a significant difference in the ADC values between malignant soft tissue tumours and benign masses (p<0.001) and within different grades of malignancy (p<0.02). Selection of 1.34×10^?3 mm²/s as a threshold ADC value for differentiating malignant soft tissue tumours from benign masses resulted in an accuracy of 91%, sensitivity of 94%, specificity of 88% and area under the curve of 0.869. There was a significant difference in the ADC value between well- and poorly differentiated malignancies (p=0.001).

Conclusions

Diffusion-weighted echo-planar MR imaging is a promising noninvasive modality that may be helpful in differentiating malignant soft tissue tumours from benign masses as well as in grading malignancy.     

Distinguishing enhancing from nonenhancing renal masses with dual-source dual-energy CT: iodine quantification versus standard enhancement measurements

Purpose

To compare the diagnostic accuracy of iodine quantification and standard enhancement measurements in distinguishing enhancing from nonenhancing renal masses.

Materials and methods

The Institutional Review Board approved this retrospective study conducted from data found in institutional patient databases and archives. Seventy-two renal masses were characterised as enhancing or nonenhancing using standard enhancement measurements (in HU) and iodine quantification (in mg/ml). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of standard enhancement measurements and iodine quantification were calculated from χ ² tests of contingency with histopathology or imaging follow-up as the reference standard. Difference in accuracy was assessed by means of McNemar analysis.

Results

Sensitivity, specificity, PPV, NPV and diagnostic accuracy for standard enhancement measurements and iodine quantification were 77.7 %, 100 %, 100 %, 81.8 %, 89 % and 100 %, 94.4 %, 94.7, 100 % and 97 %, respectively. The McNemar analysis showed that the accuracy of iodine quantification was significantly better (P?<?0.001) than that of standard enhancement measurements.

Conclusion

Compared with standard enhancement measurements, whole-tumour iodine quantification is more accurate in distinguishing enhancing from nonenhancing renal masses.

Key Points

? Enhancement of renal lesions is important when differentiating benign from malignant tumours. ? Dual-energy CT offers measurement of iodine uptake rather than mere enhancement values. ? Whole-tumour iodine quantification seems more accurate than standard CT enhancement measurements.     

What are the characteristics of breast cancers misclassified as benign by quantitative ultrasound shear wave elastography?

Objectives

Shear wave elastography (SWE) is a promising adjunct to greyscale ultrasound in differentiating benign from malignant breast masses. The purpose of this study was to characterise breast cancers which are not stiff on quantitative SWE, to elucidate potential sources of error in clinical application of SWE to evaluation of breast masses.

Methods

Three hundred and two consecutive patients examined by SWE who underwent immediate surgery for breast cancer were included. Characteristics of 280 lesions with suspicious SWE values (mean stiffness >50 kPa) were compared with 22 lesions with benign SWE values (<50 kPa). Statistical significance of the differences was assessed using non-parametric goodness-of-fit tests.

Results

Pure ductal carcinoma in situ (DCIS) masses were more often soft on SWE than masses representing invasive breast cancer. Invasive cancers that were soft were more frequently: histological grade 1, tubular subtype, ≤10 mm invasive size and detected at screening mammography. No significant differences were found with respect to the presence of invasive lobular cancer, vascular invasion, hormone and HER-2 receptor status. Lymph node positivity was less common in soft cancers.

Conclusion

Malignant breast masses classified as benign by quantitative SWE tend to have better prognostic features than those correctly classified as malignant.

Key points:

? Over 90?% of cancers assessable with ultrasound have a mean stiffness >50 kPa. ? ‘Soft’ invasive cancers are frequently small (≤10 mm), low grade and screen-detected. ? Pure DCIS masses are more often soft than invasive cancers (>40?%). ? Large symptomatic masses are better evaluated with SWE than small clinically occult lesions. ? When assessing small lesions, ‘softness’ should not raise the threshold for biopsy.