Intra-scan inter-tissue variability can help harmonize radiomics features in CT.

OBJECTIVE: We studied the repeatability and the relative intra-scan variability across acquisition protocols in CT using phantom and unenhanced abdominal series. METHODS: We used 17 CT scans from the Credence Cartridge Radiomics Phantom database and 20 unenhanced multi-site non-pathologic abdominal patient series for which we measured spleen and liver tissues. We performed multiple measurements in extracting 9 radiomics features. We defined a "tandem" as the measurement of a given tissue (or material) by a given radiomics. For each tandem, we assessed the proportion of the variability attributable to repetitions, acquisition protocols, material, or patient. We analyzed the distribution of the intra-scan correlation between pairs of tandems and checked the impact of correlation coefficient greater than 0.90 in comparing paired and unpaired differences. RESULTS: The repeatability of radiomics features depends on the measured material; 56% of tandems were highly repeatable. Histogram-derived radiomics were generally less repeatable. Nearly 60% of relative radiomics measurements had a correlation coefficient higher than 0.90 allowing paired measurements to improve reliability in detecting the difference between two materials. The analysis of liver and spleen tissues showed that measurement variability was negligible with respect to other variabilities. As for phantom data, we found that gray level zone length matrix (GLZLM)-derived radiomics and gray level co-occurrence matrix (GLCM)-derived radiomics were the most correlating features. For these features, relative intra-scan measurements improved the detection of different materials or tissues. CONCLUSIONS: We identified radiomics features for which the intra-scan measurements between tissues are linearly correlated. This property represents an opportunity to improve tissue characterization and inter-site harmonization. KEY POINTS: • The repeatability of radiomics features on CT depends on the measured material or tissue. • Some tandems of radiomics features/tissues are linearly affected by the variability of acquisition protocols on CT. • Relative intra-scan measurements are an opportunity for improving quantitative imaging on CT.

Harmonization of radiomic feature distributions: impact on classification of hepatic tissue in CT imaging.

OBJECTIVES: Following the craze for radiomic features (RF), their lack of reliability raised the question of the generalizability of classification models. Inter-site harmonization of images therefore becomes a central issue. We compared RF harmonization processing designed to detect liver diseases in CT images. METHODS: We retrospectively analyzed 76 multi-center portal CT series of non-diseased (NDL) and diseased liver (DL) patients. In each series, we positioned volumes of interest in spleen and liver, then extracted 9 RF (histogram and texture). We evaluated two RF harmonization approaches. First, in each series, we computed the Z-score of liver measurements based on those computed in the spleen. Second, we evaluated the ComBat method according to each imaging center; parameters were computed in the spleen and applied to the liver. We compared RF distributions and classification performances before/after harmonization. We classified NDL versus spleen and versus DL tissues. RESULTS: The RF distributions were all different between liver and spleen (p < 0.05). The Z-score harmonization outperformed for the detection of liver versus spleen: AUC = 93.1% (p < 0.001). For the detection of DL versus NDL, in a case/control setting, we found no differences between the harmonizations: mean AUC = 73.6% (p = 0.49). Using the whole datasets, the performances were improved using ComBat (p = 0.05) AUC = 82.4% and degraded with Z-score AUC = 67.4% (p = 0.008). CONCLUSIONS: Data harmonization requires to first focus on data structuring to not degrade the performances of subsequent classifications. Liver tissue classification after harmonization of spleen-based RF is a promising strategy for improving the detection of DL tissue. KEY POINTS: • Variability of acquisition parameter makes radiomics of CT features non-reproducible. • Data harmonization can help circumvent the inter-site variability of acquisition protocols. • Inter-site harmonization must be carefully implemented and requires designing consistent data sets.

Age-related schwannomatosis with potential exosome-mediated contribution to prostate hyperplasia: a case report and mini-review.

A 72-year-old Caucasian man incurring a prostate hypertrophy presented with a right forearm nodule, the growth of which appeared to parallel the rise in his blood prostate-specific antigen (PSA) level. Echographic examination was consistent with a median-nerve schwannoma, and was confirmed upon magnetic resonance imaging (MRI). Excision of the nodule was readily performed without significant neural damage, and its schwannoma nature was confirmed upon immunohistochemistry analysis. Importantly, blood PSA dropped abruptly from ≈13 to ≈5 ng/ml within 2 months postschwannoma resection, a swift drastic reduction unachievable with oral dutasteride alone. However, 6 weeks later, a new nodule became apparent on the back of the left knee and was identified as a second schwannoma, thereby suggesting that its growth could have been stimulated by the resection of the first schwannoma, as previously described for vestibular schwannomas. The second schwannoma was in fact two: the bigger one was in the common fibular nerve and the smaller one in the tibial nerve. Both echography and MRI results were confirmed upon surgical resection of the bigger knee schwannoma. Although the third schwannoma has not yet been resected and formally characterized, we face a schwannomatosis case with an unexpected potential exosome-mediated stimulating effect on PSA secretion (PSA immunohistochemistry was negative on both schwannomas). On the other hand, preliminary genomic analysis showed a deficient balance for chromosome 22, the very chromosome carrying the three main genes involved in schwannomatosis. This age-related schwannomatosis case is thus discussed in light of the following: age-related DNA repair deficiency culminating in loss of chromosome/heterozygosity; CpG methylation/demethylation-based epigenetic aging; age-related functional decline of the immune system responsible for inefficient elimination of abnormal cells and subsequent tumorigenic cell turn-over; exosome-mediated pathologic intercellular communications; and prostate-invading brain neural progenitors as pathologic peripheral nervous system (PNS) cells.

Interest of systematic tomosynthesis (3D mammography) with synthetic 2D mammography in breast cancer screening.

Full field digital mammography (FFDM) is the current pillar of breast cancer screening program. However, the emerging technique digital breast tomosynthesis (DBT) has demonstrated a significant increase in the sensibility of cancer detection in several large cohort trials. DBT is particularly helpful for young patients, dense breasts and soft masses due to its ability to reduce overlapping of tissue. In such a population of women, radiologists are more confident and the recall rates are reduced together with a higher positive predictive value. To reduce the breast absorbed doses of screened women and facilitate the workflow, a synthetized two-dimensional (2D) digital mammography (sDM) is obtained from DBT to replace the FFDM. No significant differences regarding detection of anomalies have been reported with respect to FFDM. These results validate a modern strategy for breast cancer screening supported by two views of DBT with sDM. In terms of mean absorbed doses, this strategy is around 1.5 mGy/view and almost equivalent to FFDM. In Europe, major limitations to such evolution are public health policies especially agreements and reimbursement for the technique being used in organized screening.

Reversible uro-lymphatic fistula.

Renal lymphatic fistulas are rare and, in most cases, of parasitic origin. We report a case of a reversible uro-lymphatic fistula, which was demonstrated by CT and was felt to be secondary to a radiolucent calculus.

Uterine inversion caused by a submucous leiomyoma.

Uterine inversion secondary to a pathological process of the myometrium is very rare. We report the case of a woman presenting with a submucosal pedunculated leiomyoma in whom a study by 3-T magnetic resonance imaging (MRI) demonstrated a uterine inversion. The MRI findings were characteristic and permitted a correct diagnosis before the surgical intervention.

Solitary intraperitoneal fibrous tumor: report of three cases.

The solitary intraperitoneal fibrous tumor is a rare lesion, almost exclusively benign. We report on three cases with different ultrasound, computed tomography and magnetic resonance imaging findings, related to the fibrous and/or cellular histological composition of the tumor. Because of the minimal, but real, possibility of a recurrence after the surgical intervention, a follow-up by radiological imaging is recommended.

Two rare cases of spontaneous splenic rupture.

The rupture of the spleen, not secondary to external trauma, is rare. Two cases are reported. The first case occurred in a patient with an aggressive form of lymphoma, and the second in a patient following a colonoscopy. In the rare occurrences of spontaneous rupture, radiological imaging, in particular by computed tomography, will lead to the diagnosis and help in deciding the correct treatment.

Endometriosis following cesarean section: ultrasonography and magnetic resonance imaging.

We present three cases of endometriosis developing in the abdominal wall following cesarean section. The patients were examined by Doppler ultrasonography (US) and magnetic resonance imaging (MRI). The object is to describe the US and MRI findings of the lesion and evaluate their role in the diagnosis and management. In our opinion, a single procedure is sufficient in evaluating the lesion and in reaching the diagnosis.

Lipomas of the right colon: report on six cases.

We report six cases of lipomas of the right colon, of which one was affected by two lesions. Two cases presented with episodes of partial occlusion; the others did not present with particular symptoms. The diagnoses were based on imaging by computed tomography, which demonstrated an intraluminal formation of fatty density, not associated with tissual components or hypervascularization.

Lipomatous tumors of the adrenals--a report on 18 cases and review of the literature.

The lipomatous tumors of the adrenals are hormonally inactive lesions, often of a benign nature, such as myelolipomas, lipomas, angiomyolipomas, or mature teratomas, and are rarely malignant, such as liposarcomas. The importance of recognizing their characteristic radiological images, which would lead to their correct treatment, is fundamental since there has been an increase in the demonstration of this lesion, often detected incidentally. The various imaging procedures, although not allowing to formulate a histological diagnosis, nonetheless permit to determine the volume of the tumoral mass and their evolution. These two factors are of significant importance in the planning of the correct surgical procedure, while a third important factor is the proper evaluation of the symptoms presented by the patient. Regarding the treatment, on the basis of our own experience, which agrees with that of other authors, the surgical removal of any lesion greater than 5 cm is mandatory.

Subumbilical parietal cystic images.

We report three cases of women who came to our observation suffering from a feeling of heaviness in the pelvic floor. Ultrasonography showed, in all cases, a cystic formation, medially located under the umbilicus, suggesting the presence of a cyst of the urachus. Computed tomography and magnetic resonance imaging, however, thanks to a more definite topographic evaluation, allowed elimination of this diagnosis in two patients with history of previous abdominal surgery.

Inguinal herniation of a bladder diverticulum.

The inguinal herniation of a bladder diverticulum is a rare entity. We report two cases and describe the findings observed by computed tomography, which allowed demonstration of the site and contents of the hernia.

[Primary pleomorphic rhabdomyosarcoma of the kidney in adults: unusual tumor]. / Rhabdomyosarcome pléomorphe primitif du rein chez l'adulte: une tumeur rare.

Primary rhabdomyosarcoma (RMS) of the kidney in an adult is a very rare and unusual tumor in this site. The clinical signs associated with the flank tumoral syndrome, the histologic appearance of cytoplasmic double striation in rhabdomyoblasts and the immunohistochemical expression of skeletal muscle differentiation (desmin, myoglobin, myogenin) are described in the context of a rapidly evolving renal RMS in a 77-year old man. The differential diagnosis are mainly represented by sarcomatoid renal cell carcinoma. According to the neoplastic extent, the treatment includes radical nephrectomy, chemotherapy and surgery. The prognosis of primary renal RMS is extremely poor, with lymph node, hepatic, bone marrow and pulmonary metastasis and a short survival rate.