Bone echinococcosis with hip localization: A case report with evaluation of imaging features.

Hydatid disease (HD) is a zoonotic parasitic disease caused by the larvae of Echinococcus. Bone echinococcosis is rare, accounting for 0.5% to 4% of all echinococcosis. We describe a particular case of pelvic echinoccosis. A 29-year-old man initially presents with pain in his left hip for several years. After an accidental fall from a tree, he suffered a fracture of the left acetabulum. X-rays and CT scans showed an osteolytic area of the acetabulum with bony cortical interruption. MR imaging demonstrated extensive area of osteostructural alteration of the iliac wing and the left acetabulum due to multiple cysts with enhancement of the walls after administration of Gadolinium-based contrast agents. A CT-guided biopsy of an osteolytic area was performed with diagnosis of echinococcus cyst. He underwent albendazole therapy and subsequently echinococcus cyst exeresis, bone curettage, and left hip arthroplasty. Twenty-two months after surgery, CT scan showed recurrence of disease. After 4 years and 6 months of chronic therapy CT scan showed an increase in size of the cyst at the site of the disease recurrence. Five years and 4 months after the first operation, a new cyst exeresis and pelvic bone curettage with implant retention was performed. This case report demonstrates that hydatid cysts should be considered as a possible cause for non-specific pelvic pain, especially in endemic locations.

Comparing the first and the second waves of COVID-19 in Italy: differences in epidemiological features and CT findings using a semi-quantitative score.

PURPOSE: CT findings of hospitalized COVID-19 patients were analyzed during both the first and the second waves of the pandemic, in order to detect any significant differences between the two groups. METHODS: In this observational, retrospective, monocentric study, all hospitalized patients who underwent CT for suspected COVID-19 pneumonia from February 27 to March 27, 2020 (first wave) and from October 26 to November 24, 2020 (second wave) were enrolled. Epidemiological data, radiological pattern according to the RSNA consensus statement and visual score extension using a semi-quantitative score were compared. RESULTS: Two hundred and eleven patients (mean age, 64.52 years ± 15.14, 144 males) were evaluated during the first wave while 455 patients (mean age, 68.26 years ± 16.34, 283 males) were studied during the second wave. The same prevalence of patterns was documented in both the first and the second waves (p = 0.916), with non-typical patterns always more frequently observed in elderly patients, especially the "indeterminate" pattern. Compared to those infected during the first wave, the patients of the second wave were older (64.52 vs.68.26, p = 0.005) and presented a slightly higher mean semi-quantitative score (9.0 ± 2.88 vs. 8.4 ± 3.06, p = 0.042). Age and semi-quantitative score showed a positive correlation (r = 0.15, p = 0.001). CONCLUSIONS: There was no difference regarding CT pattern prevalence between the first and the second waves, confirming both the validity of the RSNA consensus and the most frequent radiological COVID-19 features. Non-typical COVID-19 features were more frequently observed in older patients, thus should not be underestimated in the elderly population.

Imaging-based diagnosis of benign lesions and pseudolesions in the cirrhotic liver.

Liver cirrhosis is a leading cause of death worldwide, with 1-year mortality rates of up to 57% in decompensated patients. Hepatocellular carcinoma (HCC) is the most common primary tumor in cirrhotic livers and the second leading cause of cancer-related mortality worldwide. Annually, up to 8% of patients with cirrhosis develop HCC. The diagnosis of HCC rarely requires histological confirmation: in fact, according to the most recent guidelines, the imaging features of HCC are almost always sufficient for a certain diagnosis. Thus, the role of the radiologist is pivotal because the accurate detection and characterization of focal liver lesions in patients with cirrhosis are essential in improving clinical outcomes. Despite recent technical innovations in liver imaging, several issues remain for radiologists regarding the differentiation of HCC from other hepatic lesions, particularly benign lesions and pseudolesions. It is important to avoid misdiagnosis of benign liver lesions as HCC (false-positive cases) because this diagnostic misinterpretation may lead to ineligibility of a patient for potentially curative treatments or inappropriate assignment of high priority scores to patients on waiting lists for liver transplantation. This review presents a pocket guide that could be useful for the radiologist in the diagnosis of benign lesions and pseudolesions in cirrhotic livers, highlighting the imaging features that help in making the correct diagnosis of macroregenerative nodules; siderotic nodules; arterioportal shunts; hemangiomas, including fast-filling hemangiomas, hemangiomas with pseudowashout, and sclerosed hemangiomas; confluent fibrosis; pseudomasses in chronic portal vein thrombosis; and focal fatty changes.

Texture Analysis on Ultrasound: The Effect of Time Gain Compensation on Histogram Metrics and Gray-Level Matrices.

AIMS: Texture analysis (TA) is becoming an increasingly used tool in radiological research. Some papers have been published on its use in ultrasound (US), but the way in which the machine settings affect the features has not yet been fully explored. With this research, we analyze how the time gain compensation (TGC) influences the features of the gray-level matrices in the abdominal US setting. SUBJECTS AND METHODS: We analyzed the images acquired from the hepatorenal acoustic window of a healthy 29-year-old volunteer acquired with different TGC settings. TA was carried out using the LifeX software. RESULTS: Several both 1st and 2nd order gray-level matrices features showed a strong correlation with TGC settings. CONCLUSIONS: TGC settings must be accounted for when carrying out further TA studies.

Diagnostic Accuracy of North America Expert Consensus Statement on Reporting CT Findings in Patients Suspected of Having COVID-19 Infection: An Italian Single-Center Experience.

PURPOSE: To evaluate the diagnostic accuracy of the four standardized categories for CT reporting proposed by the Radiological Society of North America (RSNA) to support a faster triage compared with real-time reverse-transcription polymerase chain reaction (RT-PCR), which is the reference standard for suspected coronavirus disease 2019 (COVID-19), but has long reporting time (6-48 hours). MATERIALS AND METHODS: A retrospective analysis of 569 thin-section CT examinations performed for patients suspected of having COVID-19 from February 27 to March 27, 2020 (peak of infection in Italy) was conducted. The imaging pattern was classified according to the statement by the RSNA as "typical," "indeterminate," "atypical," and "negative" and compared with RT-PCR for 460 patients. Interobserver variability in reporting between a senior and a junior radiologist was evaluated. Use of the vascular enlargement sign in indeterminate cases was also assessed. RESULTS: The diagnosis of COVID-19 was made in 45.9% (211/460) of patients. The "typical" pattern (n = 172) showed a sensitivity of 71.6%, a specificity of 91.6%, and a positive predictive value of 87.8% for COVID-19. The "atypical" (n = 67) and "negative" (n = 123) pattern demonstrated a positive predictive value of 89.6% and 86.2% for non-COVID-19, respectively. The "indeterminate" (n = 98) pattern was nonspecific, but vascular enlargement was most frequently found in patients with COVID-19 (86.1%; P < .001). Interobserver agreement was good for the "typical" and "negative" pattern and fair for "indeterminate" and "atypical" (κ = 0.5; P = .002). CONCLUSION: In an epidemic setting, the application of the four categories proposed by the RSNA provides a standardized diagnostic hypothesis, strongly linked to the RT-PCR results for the "typical," "atypical," and "negative" pattern. In the "indeterminate" pattern, the analysis of the vascular enlargement sign could facilitate the interpretation of imaging features.© RSNA, 2020.

LI-RADS: a great opportunity not to be missed.

The Liver Imaging Reporting and Data System (LI-RADS) is a widespread comprehensive system for standardising the reporting and data collection of liver imaging to standardise chronic liver disease evaluation. However, the LI-RADS, based on the identification of some categories of lesions by means of a conceptual and nonquantitative probability approach, has many limitations. In fact, recently, the European Association for the Study of the Liver Guidelines regarding the management of hepatocellular carcinoma did not accept the LI-RADS. The aim of this paper was to critically analyse the LI-RADS, focusing on some interesting issues such as the absence of a clear distinction between two different imaging modalities (computed tomography and MRI), the lack of validation of some major features, the assessment of its ancillary features and its complexity. Despite these limitations, the LI-RADS represents a great opportunity for the radiological community. We must not let it escape, but time and experience are necessary for its improvement.

Which is the best MRI marker of malignancy for atypical cirrhotic nodules: hypointensity in hepatobiliary phase alone or combined with other features? Classification after Gd-EOB-DTPA administration.

PURPOSE: To investigate whether the malignancy of atypical nodules in cirrhosis can be identified at gadoxetic-acid-disodium(Gd-EOB-DTPA)-MRI by their hypointensity in the hepatobiliary(HB)-phase alone or combined with any other MR imaging features. MATERIALS AND METHODS: One hundred eleven atypical nodules detected in 77 consecutive Gd-EOB-DTPA-MRIs were divided, based on arterial-phase behavior, into: Class I, isovascular (n = 82), and Class II, hypervascular without portal/delayed washout (n = 29). The two classes were further grouped based on HB-phase intensity (A/B/C hypo/iso/hyperintensity). Portal/venous/equilibrium-phase behavior and T2w features were also collected. Histology was the gold standard. Per-nodule sensitivity, specificity, negative and positive predictive values (NPV/PPV), and diagnostic accuracy were calculated for HB-phase hypointensity alone, and combined with vascular patterns and T2w hyperintensity. RESULTS: Histology detected 60 benign and 51 malignant/premalignant nodules [10 overt hepatocellular carcinomas (HCCs) and 41 high-grade dysplastic nodules (HGDN)/early HCC]. Class IA contained 31 (94%) malignancies, IB one (3%), and IC only benign lesions. Class IIA had 100% malignancies, IIB three (37.5%) and IIC only two (28.5%). HB-phase hypointensity alone (Classes I-IIA) had 88% sensitivity, 91% NPV, and 93% diagnostic accuracy, superior (P < 0.05, P < 0.006, and P < 0.05, respectively) to any other MR imaging feature alone or combined. CONCLUSION: In atypical cirrhotic nodules, HB-phase hypointensity by itself is the strongest marker of malignancy.

Large regenerative nodules in a patient with Budd-Chiari syndrome after TIPS positioning while on the liver transplantation list diagnosed by Gd-EOB-DTPA MRI.

BACKGROUND: Large regenerative nodules (LRNs) are hyperplastic benign nodules most commonly associated with Budd-Chiari syndrome (BCS), caused by outflow obstruction of the hepatic veins or vena cava. To our knowledge, no cases of LRNs arising in BCS after transjugular intrahepatic portosystemic shunt (TIPS) positioning and detected by Gd-EOB-DTPA MRI have been reported in the literature. METHODS: A 58-year-old woman with BCS, on the liver transplantation (LT) list, underwent a follow-up enhanced MRI. Two years earlier, a TIPS had been placed. In 2008, recurrent hepaticoencephalopathy resistant to medical treatment fulfilled the LT criteria for BCS treated with TIPS and the patient was therefore added to the LT list. CT performed before TIPS had not detected any hepatic lesions. CT performed six months after TIPS showed its complete patency but documented two indeterminate hypervascular liver lesions. RESULTS: MRI performed with Gd-EOB-DTPA revealed additional hypervascular lesions with uptake and retention of the medium in the hepatobiliary phase, thus reflecting a benign behavior of hepatocellular composition. These MRI features were related to LRNs as confirmed by histopathologic analysis. CONCLUSIONS: Gd-EOB-DTPA-enhanced MRI is potentially superior to standard imaging using gadolinium chelates or spiral CT, especially for the differential diagnosis of hypervascular lesions. Gd-EOB-DTPA MRI may become the imaging method of choice for evaluating LT list patients with BCS after TIPS placement.

Contribution of the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI to Dynamic MRI in the detection of hypovascular small (≤ 2 cm) HCC in cirrhosis.

OBJECTIVE: To prospectively assess the additional value of the hepatobiliary (HB) phase of Gd-EOB-DTPA-MRI in identifying and characterising small (≤ 2 cm) hepatocellular carcinomas (HCCs) undetermined in dynamic phases alone because of their atypical features, according to the AASLD criteria. METHODS: 127 cirrhotic patients were evaluated with Gd-EOB-DTPA-MRI in two sets: unenhanced and dynamic phases; unenhanced, dynamic and HB phases. Sixty-two out of 215 nodules (29%) were atypical in 42 patients (33%). RESULTS: 62 atypical nodules were reported at histology: high-grade dysplastic nodules (HGDN)/early HCC (n = 20), low-grade DN (LGDN) (n = 21), regenerative nodules (n = 17) and nodular regenerative hyperplasia (n = 4). The sensitivity, specificity, accuracy, positive and negative predictive value (PPV, NPV) were increased by the addition of the HB phase: 88.4-99.4%, 88-95%, 88-98.5%, 97-99%, and 65-97.5%, respectively. Twenty atypical nodules were malignant (32%), 19 of which were characterised only during the HB phase. CONCLUSIONS: The HB phase is 11% more sensitive in the classification of HGDN/early HCC than dynamic MRI, with an added value of 32.5% in the NPV. The high incidence (33%) of atypical nodules and their frequent malignancy (32%) suggest the widespread employment of Gd-EOB-DTPA-MRI in the follow-up of small nodules (≤ 2 cm) in cirrhosis.

MR monitoring of cyclooxygenase-2 inhibition of angiogenesis in a human breast cancer model in rats.

PURPOSE: To prospectively evaluate the ability of macromolecular contrast medium (MMCM)-enhanced dynamic magnetic resonance (MR) imaging to depict vascular changes in response to cyclooxygenase-2 (COX-2) inhibition of angiogenesis in a human breast cancer model. MATERIALS AND METHODS: The institutional committee for animal research approved this study. A human breast cancer cell line, MDA-MB-231, was implanted in 30 female homozygotous athymic rats that were alternately assigned to either a drug treatment group that received celecoxib on a daily basis for 7 days or a control group that received saline. Each animal underwent MR imaging after intravenous administration of a high-molecular-weight contrast agent at baseline and again 24 hours and 7 days after administration. Eleven rats in each group successfully underwent all three studies and had data sets of sufficient technical quality. A bidirectional two-compartment tissue model was used to estimate transendothelial permeability (K(PS)) and fractional plasma volume (fPV) for each tumor. Microvessel density was also measured to enable histologic assessment of angiogenesis. Repeated-measures analysis of variance and unpaired two-tailed t tests were used to evaluate differences in mean values between MR examinations performed in the same rats and between baseline values in treated and control rats, respectively. RESULTS: MR imaging-assayed microvascular K(PS) decreased significantly after 7 days of treatment with celecoxib (P < .05), but it was not significantly changed after 7 days in the control group. Likewise, microvascular density, a histologic surrogate of angiogenesis, was significantly (P < .05) lower in the treatment group than in the control group. The fPV did not significantly change in either group. CONCLUSION: Dynamic MR imaging revealed microvascular permeability to a high-molecular-weight contrast agent was significantly reduced by treatment with celecoxib.

In-vivo NIR autofluorescence imaging of rat mammary tumors.

We investigate in vivo detection of mammary tumors in a rat model using autofluorescence imaging in the red and far-red spectral regions. The objective was to explore this method for non-invasive detection of malignant tumors and correlation between autofluorescence properties of tumors and their pathologic status. Eighteen tumor-bearing rats, bearing eight benign and seventeen malignant tumors were imaged. Autofluorescence images were acquired using spectral windows centered at 700-nm, 750-nm and 800-nm under laser excitation at 632.8-nm and 670- nm. Intensity in the autofluorescence images of malignant tumors under 670-nm excitation was higher than that of the adjacent normal tissue. whereas intensity of benign tumors was lower compared to normal tissue.

Initial computed tomography imaging experience using a new macromolecular iodinated contrast medium in experimental breast cancer.

OBJECTIVE: The objective of this study was to evaluate computed tomography (CT) enhancement characteristics for a new iodinated macromolecular contrast medium (MMCM), PEG12000-Gen4-triiodo, for angiographic effect and for assessment of abnormal vascular permeability in cancer. MATERIALS AND METHODS: Time persistence of angiographic effect was evaluated on rat CT images acquired over 30 minutes using the iodinated polyethyleneglycol- (PEG) based macromolecule. Dynamic CT imaging after PEG12000-Gen4-triiodo-enhancement in tumor-bearing rats was used to quantitatively estimate plasma volume and microvascular transendothelial permeability for both tumor and normal soft tissue. Using identical doses of iodine, 300 mg iodine/kg, blood curves for this MMCM and iohexol were compared. RESULTS: Serial whole-body CT angiograms using PEG12000-Gen4-triiodo showed diagnostic vascular detail through 20 minutes, and the blood enhancement curve was higher and more persistent than with small-molecular iohexol. Permeability estimates were significantly (P<0.02; paired t test) higher in tumors (48.2+/-18.1 microL/min-1 100 mL) than in muscle (2.5+/-5.7 microL/min-1 100 mL). CONCLUSIONS: Use of PEG-based MMCM for experimental CT allowed for a persistent angiographic enhancement and for quantitative estimation of tumor microvascular characteristics.

MR angiography of the carotid arteries: parameters affecting image quality.

RATIONALE AND OBJECTIVES: This study was performed to evaluate the relationship between dose levels of contrast medium and image quality in magnetic resonance (MR) angiography of the carotid arteries with fluoroscopically monitored, manually triggered, elliptically ordered image acquisitions. MATERIALS AND METHODS: Twenty-five patients with clinical indications for angiography of the carotid arteries were examined with MR at 1.5 T by using a fluoroscopically monitored, manually triggered, elliptically ordered pulse sequence with the administration of one of three different volumes of gadolinium-based contrast medium. The signal intensities of the vessel lumen and the surrounding tissues were measured in single partitions at the origin of the common carotid artery, the carotid bifurcation, and the intracranial internal carotid arteries. The contrast-to-noise ratio in these regions of interest also was measured. Maximum intensity projection image quality was appraised for blurring, artifacts, venous enhancement, background suppression, and contrast medium distribution. RESULTS: No artifacts or venous enhancement was observed. The position of the fluoroscopic section affected the distribution of contrast medium along the vessel, as evidenced by the difference between the contrast-to-noise ratio at the origin of the common carotid artery and the ratio at the carotid bifurcation and the intracranial internal carotid arteries (P < .01). The contrast medium dose administered was strongly correlated with image quality (r = 0.90). CONCLUSION: Contrast medium dose is related to image quality in MR angiography of the carotid arteries performed with elliptical ordering, fluoroscopic monitoring, and manual triggering.