Ultra-low-dose unenhanced chest CT: Prospective comparison of high kV/low mA versus low kV/high mA protocols.

PURPOSE: To qualitatively and quantitatively compare unenhanced ultra-low-dose chest computed tomography (ULD-CT) acquired at 80kVp and 135kVp. MATERIALS AND METHODS: Fifty-one patients referred for unenhanced chest CT were prospectively included. There were 29 men and 22 women, with a mean age of 64.7±11.6 (SD) years (range: 35-91 years) and a mean body mass index of 26.2±6.3 (SD) (range: 17-54.9). All patients underwent two different ULD-CT protocols (80kVp-40mA and 135kVp-10mA). Image quality of both ULD-CT examinations using a 5-level scale as well as assessability of 6 predetermined lung parenchyma lesions were blindly evaluated by three radiologists and compared using a logistic regression model. Image noise of the two protocols was compared with Wilcoxon signed-rank test. RESULTS: The mean dose-length product at 80kVp and at 135kVp were 14.7±1.8 (SD) mGy.cm and 15.6±1.9 (SD) mGy.cm, respectively (P<0.001). Image noise was significantly lower at 135kVp (58.9±12.4) than at 80kVp (74.7±14.5) (P<0.001). For all readers and for all examinations, the 135kVp protocol yielded better image quality than 80kVp protocol, with a mean qualitative score of 4.5±0.7 versus 3.9±0.8 (P<0.001). The 135kVp protocol was significantly more often of diagnostic quality than the 80kvp protocol (92.3% versus 77.8%, respectively) (P<0.001) and was less prone to image quality deterioration in obese patients. Parenchymal lesions were never better depicted on the 80kVp protocol than with the 135kVp protocol. CONCLUSION: Unenhanced chest ULD-CT should be acquired at a high kilovoltage and low current, such as 135kVp-10mA, over a low kilovoltage and high current protocol.

Single source dual energy CT: What is the optimal monochromatic energy level for the analysis of the lung parenchyma?

OBJECTIVE: To determine the optimal monochromatic energy level for lung parenchyma analysis in spectral CT. METHODS: All 50 examinations (58% men, 64.8±16yo) from an IRB-approved prospective study on single-source dual energy chest CT were retrospectively included and analyzed. Monochromatic images in lung window reconstructed every 5keV from 40 to 140keV were independently assessed by two chest radiologists. Based on the overall image quality and the depiction/conspicuity of parenchymal lesions, each reader had to designate for every patient the keV level providing the best diagnostic and image quality. RESULTS: 72% of the examinations exhibited parenchymal lesions. Reader 1 picked the 55keV monochromatic reconstruction in 52% of cases, 50 in 30% and 60 in 18%. Reader 2 chose 50keV in 52% cases, 55 in 40%, 60 in 6% and 40 in 2%. The 50 and 55keV levels were chosen by at least one reader in 64% and 76% of all patients, respectively. Merging 50 and 55keV into one category results in an optimal setting selected by reader 1 in 82% of patients and by reader 2 in 92%, with a 74% concomitant agreement. CONCLUSION: The best image quality for lung parenchyma in spectral CT is obtained with the 50-55keV monochromatic reconstructions.

[What future for chest x-ray against ultra-low-dose computed tomography?] / Quel avenir pour la radiographie thoracique face au scanner ultra-low dose ?

Technological improvements, with iterative reconstruction at the foreground, have lowered the radiation dose of a chest CT close to that of a PA and lateral chest x-ray. This ultra-low dose chest CT (ULD-CT) has an image quality that is degraded on purpose, yet remains diagnostic in many clinical indications. Thus, its effectiveness is already validated for the detection and the monitoring of solid parenchymal nodules, for the diagnosis and monitoring of infectious lung diseases and for the screening of pleural lesions secondary to asbestos exposure. Its limitations are the analysis of the mediastinal structures, the severe obesity (BMI>35) and the detection of interstitial lesions. If it can replace the standard chest CT in these indications, all the more in situations where radiation dose is a major problem (young patients, repeated exams, screening), it progressively emerges as a first line alternative for chest radiograph, providing more data at a similar radiation cost.

[Pre- and postoperative imaging of type B aortic dissection]. / Imagerie de la dissection aortique de type B : ce que veut savoir le chirurgien avant et après l'intervention.

Type B aortic dissections are serious diseases with a 60 to 80 % 5-year survival rate. Although typically managed with a medical treatment, surgery may be necessary in the acute/subacute or the chronic phase if significant complications are encountered. For these patients, CT angiography is the first-line imaging modality, used for indicating and preparing the surgical procedure as well as for follow-up. Physicians in charge of these patients should be familiar with the key reading points. Visceral malperfusion is the most common acute complication, while aneurysmal dilatation of the false lumen is the most common chronic complication, with surgical management generally indicated when the axial diameter of the aorta exceeds 55mm. Endovascular treatment tends to replace open surgery: it requires precise measurements and identification of the entry tear (contribution of 4D-MRA).

Iterative reconstruction in single source dual-energy CT pulmonary angiography: Is it sufficient to achieve a radiation dose as low as state-of-the-art single-energy CTPA?

OBJECTIVE: Dual-energy (DE) brings numerous significant improvements in pulmonary CT angiography (CTPA), but is associated with a 15-50% increase in radiation dose that prevents its widespread use. We hypothesize that thanks to iterative reconstruction (IR), single source DE-CTPA acquired at the same radiation dose that a single-energy examination will maintain an equivalent quantitative and qualitative image quality, allowing a more extensive use of the DE technique in the clinical routine. MATERIAL AND METHODS: Fifty patients (58% men, mean age 64.8yo ± 16.2, mean BMI 25.6 ± 4.5) were prospectively included and underwent single source DE-CTPA with acquisition parameters (275 mA fixed tube current, 50% IR) tweaked to target a radiation dose similar to a 100 kV single-energy CTPA (SE-CTPA), i.e., a DLP of 260 mGy cm. Thirty patients (47% men, 64.4yo ± 18.6, BMI 26.2 ± 4.6) from a previous prospective study on DE-CTPA (375 mA fixed tube current, reconstruction with filtered-back projection) were used as the reference group. Thirty-five consecutive patients (57% men, 65.8yo ± 15.5, BMI 25.7 ± 4.4) who underwent SE-CTPA on the same scanner (automated tube current modulation, 50% IR) served as a comparison. Subjective image quality was scored by two radiologists using a 5-level scale and compared with a Kruskal-Wallis nonparametric test. Density measurements on the 65 keV monochromatic reconstructions were used to calculate signal-to-noise (SNR) and contrast-to-noise (CNR) ratios that were compared using a Student's t test. Correlations between image quality, SNR, CNR and BMI were sought using a Pearson's test. p<0.05 was considered significant. RESULTS: All examinations were of diagnostic quality (score ≥ 3). In comparison with the reference DE-CTPA and the SE-CTPA protocols, the DE-IR group exhibited a non-inferior image quality (p=0.95 and p=0.21, respectively) and a significantly lower mean image noise (p<0.01 and p=0.01) thus slightly improving the SNR (p=0.09 and p=0.47) and the CNR (p=0.12 and p=0.51). There was a strong negative relationship between BMI and SNR/CNR (ρ=-0.59 and -0.55 respectively), but only a moderate negative relationship between BMI and image quality (ρ=-0.27). CONCLUSION: With iterative reconstruction, objective and subjective image quality of single source DE-CTPA are preserved even though the radiation dose is lowered to that of a single-energy examination, overcoming a major limitation of the DE technique and allowing a widespread use in the clinical routine.

Imaging before and after catheter ablation of atrial fibrillation.

Catheter ablation of arrhythmogenic triggers has been validated for the treatment of atrial fibrillation that is refractory to anti-arrhythmic medication. Imaging plays an important role in guiding the procedure as well as in planning and follow-up. The goal of pre-procedural imaging is to obtain a detailed anatomical description of the pulmonary veins, to eliminate a thrombus of the left atrium and to define the prognostic factors. MDCT angiography effectively and simply meets nearly all of these needs. Thus, a precise description of the left atrium anatomy before the procedure is a key factor to success and left atrium volume is a reliable prognostic factor of recurrence. Radiologists should be aware of early and late complications, sometimes severe such as pulmonary vein stenosis, cardiac tamponade or atrial-esophageal fistula, whose positive diagnosis is based on imaging.

Thoracic dual energy CT: acquisition protocols, current applications and future developments.

Thanks to a simultaneous acquisition at high and low kilovoltage, dual energy computed tomography (DECT) can achieve material-based decomposition (iodine, water, calcium, etc.) and reconstruct images at different energy levels (40 to 140keV). Post-processing uses this potential to maximise iodine detection, which elicits demonstrated added value for chest imaging in acute and chronic embolic diseases (increases the quality of the examination and identifies perfusion defects), follow-up of aortic endografts and detection of contrast uptake in oncology. In CT angiography, these unique features are taken advantage of to reduce the iodine load by more than half. This review article aims to set out the physical basis for the technology, the acquisition and post-processing protocols used, its proven advantages in chest pathologies, and to present future developments.

Imaging of lung transplant complications.

Since the late 1980s, lung transplantation has emerged as a valid treatment option for some patients with advanced non-neoplastic lung disease. Long-term survival of lung transplant recipients, however, is lower than that of patients with other types of transplantation, because of numerous specific postoperative complications. Thanks to X-ray and CT, radiologists can guide clinicians, helped in this diagnostic approach by the time between the date of injury and date of transplantation. We will detail in this pictorial review the immediate and late surgical complications, the immunological complications, the infectious complications and other late complications.

Can exhaled NO fraction predict radiotherapy-induced lung toxicity in lung cancer patients?

BACKGROUND: A large increase in nitric oxide fraction (FeNO) after radiotherapy (RT) for lung cancer may predict RT-induced lung toxicity. METHODS: In this study, we assessed the relationships between FeNO variations and respiratory symptoms, CT scan changes or dose volume histogram (DVH) parameters after RT. We measured FeNO before RT, 4, 5, 6, 10 weeks, 4 and 7.5 months after RT in 65 lung cancer patients. RESULTS: Eleven lung cancer patients (17%) complained of significant respiratory symptoms and 21 (31%) had radiation pneumonitis images in > 1/3 of the irradiated lung after RT. Thirteen patients (20%) showed increases in FeNO > 10 ppb. The sensitivity and specificity of a > 10 ppb FeNO increase for the diagnosis of RT-associated respiratory symptoms were 18% and 83%, respectively. There was no correlation between DVH parameters or CT scan changes after RT and FeNO variations. Three patients (5%) showed intriguingly strong (2 or 3-fold, up to 55 ppb) and sustained increases in FeNO at 4 and 5 weeks, followed by significant respiratory symptoms and/or radiation-pneumonitis images. CONCLUSION: Serial FeNO measurements during RT had a low ability to identify lung cancer patients who developed symptoms or images of radiation pneumonitis. However, three patients presented with a particular pattern which deserves to be investigated.

EGFR-TKI and lung adenocarcinoma with CNS relapse: interest of molecular follow-up.

The epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) erlotinib improves survival of lung cancer as second- or third-line therapy. However, after an initial response, most patients will recur, particularly within the central nervous system. The present study reports the case of a 27-yr-old nonsmoking male presenting with a metastatic lung adenocarcinoma with EGFR exon 19 deletion, associated with sensitivity to EGFR-TKI. Gefitinib, followed by chemotherapy and finally erlotinib resulted in prolonged disease control, until multiple liver metastases were detected. After stopping EGFR-TKI, brain metastases with carcinomatous meningitis were diagnosed. A secondary T790M mutation, associated with resistance to EGFR-TKI, was found on the liver biopsy but not in the cerebrospinal fluid. Erlotinib was reintroduced and allowed a quick neurological improvement, even though the extra-cranial disease remained resistant to erlotinib. The present report underscores the interest of molecular monitoring in lung cancer. Persistent cerebral tyrosine kinase inhibitor sensitivity should be considered in patients presenting with an early central nervous system relapse after stopping epidermal growth factor receptor tyrosine kinase inhibitor, even with a T790M-resistant mutation in noncerebral metastases. Questions remain concerning the selection of sub-clones during epidermal growth factor receptor tyrosine kinase inhibitor therapy, which could differ according to metastatic sites, especially in the central nervous system.

Type 1 diabetes and idiopathic retroperitoneal fibrosis: case report.

Retroperitoneal fibrosis is characterized by the presence of a retroperitoneal tissue, consisting of chronic inflammation and marked fibrosis, which entraps the retroperitoneal organs. In two-thirds of cases, the retroperitoneal fibrosis is idiopathic. The pathogenic mechanism is not clearly identified. We report a case of idiopathic retroperitoneal fibrosis associated with type 1 diabetes mellitus. A 61-year-old woman with C peptide negative insulindependent diabetes developed retroperitoneal fibrosis revealed by bilateral hydronephrosis. Anti-GAD 65 antibodies were positive. There were no signs of autoimmune pancreatitis: no steatorrhea, normal IgG4 isotype levels, and absence of pancreas morphological abnormalities.

[Disseminated intravascular coagulation syndrome and thromboembolic complications of non-small-cell lung cancer. A case report]. / Coagulation intravasculaire disséminée et complications thromboemboliques dans le cancer bronchique non à petites cellules. A propos d'une observation.

Hemostatic disorders can be found in approximately 90% of cancer patients, but clinical expression in only 15%. Hemorrhagic complications are more frequent in acute leukaemia; solid tumors are often associated with deep venous thromboses (DVP). Disseminated intravascular coagulation syndrome (DICS) can be latent or acute, and has various clinical presentations, occurring in the course of many serious conditions including cancer. Patients have higher morbidity and mortality. Irrespective of the etiology, DICS can be revealed by a wide variety of clinical manifestations, from mild biological hemostasis disorders, to intravascular or extravascular microthromboses or lethal hemorrhagic events. We report the case of a 45-year-old female with non-small-cell lung cancer with metastases at diagnosis. The patient developed and finally died of numberous thromboembolic events subsequent to DICS. This case illustrates some rather rare complications of DICS and offers the opportunity to discuss the main therapeutic goal in this situation, i.e. to modulate the disproportionate production of thrombin, inducing thromboses and/or hemorrhages by consumption of the cellular and plasmatic coagulation factors. This means a symptomatic and mostly etiologic treatment, especially chemotherapy which can in itself provoke thromboembolic events.

[Pituitary metastases from lung cancer. Five cases]. / Métastases hypophysaires de cancers bronchiques. A propos de 5 cas.

Pituitary metastases are rare and generally asymptomatic. We studied 5 patients with pituitary metastases from lung cancer, illustrating the different clinical features. These metastases were in these cases symptomatic with the manifestation being diabetes insipidus or visual field defect. Histological subtypes from our five patients were as well small cell or non small cell lung cancer. After diagnosis of pituitary metastasis, prognosis seems to be linked to the histological subtype and the stage of lung cancer, rather than to the presence of such metastases.

[Duplication of the superior vena cava and other malformations discovered at insertion of a port-a-cath]. / Cathéter de chambre implantable: un curieux trajet.

We report a clinical case of a persistent left superior vena cava discovered in a 50-year-old female patient when a port-a-cath was inserted. This already seldom malformation was associated with an arteria lusoria and polysplenia with left inferior vena cava with hemiazygos continuation, right-sided stomach, short pancreas, preduodenal portal vein and intestinal malrotation, but without any cardiac abnormalities.

[Diagnostic imaging of the brachial plexus and the cericothoracobrachial outlet]. / Imagerie du plexus brachial et du défilé cervico-thoracobrachial.

Imaging of the brachial plexus and of the thoracic outlet syndrome is difficult due to the complex path of the brachial plexus and the morphological variations during the movements. This imaging includes simple radiographs, computed tomographies (CT) and myelo CT scan, magnetic resonance imaging and echo-Doppler. Pathologies of this area include congenital deformities (dysplasia of the upper RIB or of the clavicle), non-malignant or malignant tumors, muscular pathologies, and pathologies of the nerve roots or trunks.

Imaging of chest wall disorders.

Pathologic processes that may involve the chest wall include congenital and developmental anomalies, inflammatory and infectious diseases, and soft-tissue and bone tumors. Many of these processes have characteristic radiologic appearances that allow definitive diagnosis. Sternal deformities can be visualized at radiography and their severity quantified with computed tomography (CT). In cervical rib, CT with multiplanar reconstruction may demonstrate relevant anatomic detail and the relationship between bone deformity and arterial compression. In Poland syndrome, radiography reveals an area of hyperlucency on the affected side, whereas CT demonstrates the absence of the greater pectoral muscle and clearly depicts associated musculoskeletal anomalies. Tuberculosis typically manifests at radiography and CT as osseous and cartilaginous destruction and soft-tissue masses with calcification and rim enhancement. Aspergillosis involving the chest wall manifests as pulmonary consolidations and permeative osteolytic changes of the rib and spine at CT and as an area of increased signal intensity at T2-weighted magnetic resonance (MR) imaging. Neurogenic tumors and hemangiomas also typically have high signal intensity at T2-weighted MR imaging. Apparent mass extension or unequivocal bone destruction seen at CT or MR imaging may indicate chest wall involvement by lymphoma. Radiologically, soft-tissue sarcomas typically appear as areas of soft-tissue density or attenuation, often associated with necrotic areas of low density or attenuation. At radiography, plasmacytoma typically manifests as well-defined, "punched-out" lytic lesions with associated extrapleural soft-tissue masses. Chondrosarcoma frequently appears as a large, lobulated excrescent mass arising from a rib with scattered flocculent calcifications characteristic of its cartilaginous mix. Familiarity with these radiologic features facilitates accurate diagnosis and optimal patient treatment.

[Imaging of non-small-cell pulmonary tumors. Therapeutic strategy]. / Imagerie des tumeurs pulmonaires non à petities cellules. La stratégie thérapeutique.

In this work the imagery of non-small cell primary bronchial cancers are reviewed. The standard chest x-ray of the thorax remains irreplaceable for the early detection of these pathologies. On the other hand, progress in imagery has propelled thoracic computed tomographic scanning to the pole position for assessing the local and regional extension of the disease as well as for distance spread of these cancers. The latest developments with spiral CT have again improved the performance of CT scanning. Magnetic resonance imaging has a few precisely defined roles in assessing the extension of bronchopulmonary cancers. In particular with involvement of the apices, the chest wall and in the extension into the cardiovascular system. In this article the emphasis is on the illustration of non-small cell bronchial cancers on computed tomography and on magnetic resonance imaging.

Environment-influenced expression of polygene mutations isolated from a natural population of Drosophila melanogaster.

Quantitative trait loci (QTLs) affecting sternopleural bristle number in Drosophila melanogaster have been mapped using phenotypic markers and progeny testing. The loci were found on four of the third chromosomes isolated from a natural population. All four loci showed large effects at the standard 25 degrees C culture temperature, but they responded in different ways when developmental temperature was lowered or raised. These data support the hypothesis that genotype x environment interactions have important influences on polygene expression, and some loci might be silent, or phenotypically neutral, under some conditions but play a large phenotypic role under others. Thus, a full cataloging of the loci contributing to mutational variance for QTLs cannot be done at just a single, controlled environmental condition.

Interventional radiologic procedures with CT guidance in cancer pain management.

Reduction of pain without systematic side effects can be achieved in advanced stages of cancer with precise percutaneous techniques guided with computed tomography (CT). CT guidance allows exact needle positioning, reducing complications and improving the results. Regional analgesia with neurolytic block (neurolysis) is achieved by injection of alcohol or phenol and involves intentional destruction of a nerve or nerves to interrupt nociceptive pathways for weeks or months. Percutaneous alcoholization of bone metastasis is indicated in patients with painful, severe, osteolytic bone metastasis if conventional anticancer therapy is ineffective and high doses of opiates are necessary to control pain and when rapid pain relief is necessary. Bone packing with acrylic glue (methyl methacrylate) is used to prevent pathologic fractures and pain in patients with vertebral body tumors and acetabular metastasis. With these techniques, the radiologist is able to play an active role in pain management and in improving the quality of life of patients with malignancies.