Compressed sensing MRI of different organs: ready for clinical daily practice?

OBJECTIVES: The aim was to evaluate the image quality and sensitivity to artifacts of compressed sensing (CS) acceleration technique, applied to 3D or breath-hold sequences in different clinical applications from brain to knee. METHODS: CS with an acceleration from 30 to 60% and conventional MRI sequences were performed in 10 different applications in 107 patients, leading to 120 comparisons. Readers were blinded to the technique for quantitative (contrast-to-noise ratio or functional measurements for cardiac cine) and qualitative (image quality, artifacts, diagnostic findings, and preference) image analyses. RESULTS: No statistically significant difference in image quality or artifacts was found for each sequence except for the cardiac cine CS for one of both readers and for the wrist 3D proton density (PD)-weighted CS sequence which showed less motion artifacts due to the reduced acquisition time. The contrast-to-noise ratio was lower for the elbow CS sequence but not statistically different in all other applications. Diagnostic findings were similar between conventional and CS sequence for all the comparisons except for four cases where motion artifacts corrupted either the conventional or the CS sequence. CONCLUSIONS: The evaluated CS sequences are ready to be used in clinical daily practice except for the elbow application which requires a lower acceleration. The CS factor should be tuned for each organ and sequence to obtain good image quality. It leads to 30% to 60% acceleration in the applications evaluated in this study which has a significant impact on clinical workflow. KEY POINTS: • Clinical implementation of compressed sensing (CS) reduced scan times of at least 30% with only minor penalty in image quality and no change in diagnostic findings. • The CS acceleration factor has to be tuned separately for each organ and sequence to guarantee similar image quality than conventional acquisition. • At least 30% and up to 60% acceleration is feasible in specific sequences in clinical routine.

[Acute pancreatitis : new aspects for the management]. / Pancréatite aiguë : quelles nouveautés dans la prise en charge ?

Acute pancreatitis is a frequent disease, with a simple course in 80 % of the cases but a high morbidity and mortality in its severe form. Biliary origin and alcohol represent 80 % of the etiologies. Except endoscopic removal of gallstone for biliary origin, treatment remains symptomatic and focuses on fluid resuscitation, effective antalgia and adapted management of nutrition. This article focuses on the novelties introduced by the revision of the Classification of Atlanta in 2012 and details current guidelines for the management of the disease. The evolution of conservative treatment has allowed to reduce and postpone need for surgery and requires an interdisciplinary collaboration between surgeons, gastroenterologists, interventional radiologists and intensivists.

La pancréatite aiguë est une maladie fréquente d'évolution simple dans 80 % des cas, mais grevée de complications et d'une mortalité importante dans sa forme sévère. Les causes biliaires et la consommation excessive d'alcool représentent 80 % des étiologies. Le traitement, hormis l'extraction de calculs par voie endoscopique si l'origine est biliaire, est symptomatique et se concentre sur une réhydratation, une antalgie efficace et une gestion adaptée des apports. Cet article s'intéresse aux nouveautés introduites par la nouvelle Classification d'Atlanta (CA) de 2012 et détaille les directives actuelles de prise en charge. L'évolution du traitement conservateur ces dernières années a permis de diminuer et repousser le recours à la chirurgie et nécessite une étroite collaboration interdisciplinaire entre chirurgiens, gastroentérologues, radiologues interventionnels et intensivistes.

[Cystic lesions of the pancreas from the general practitioner's point of view]. / Les lésions kystiques du pancréas sous l'angle du médecin de premier recours.

The detection rate of cystic lesions of the pancreas has increased following the widespread use of high-resolution imaging technologies. CT-scan, MRI and echo-endoscopy are diagnostic modalities. Pseudocyst is the most common lesion. It is benign and can be managed with endoscopic treatment. Mucinous cystic neoplasia and Intraductal Papillary Mucinous Neoplasia (IPMN) carry a risk for malignant transformation. The surgical treatment of these lesions has to be discussed by a multidisciplinary board. Serous cystic neoplasia and pseudopapillar and solid neoplasia are two rare types of lesion. The aim of this article is to present the diagnostic pathway and the management of these lesions from the general practitioner point of view.

Urinary stone detection and characterisation with dual-energy CT urography after furosemide intravenous injection: preliminary results.

OBJECTIVES: To investigate the added advantage of IV furosemide injection and the subsequent urine dilution in the detection of urinary calculi in the excretory phase of dual-source dual-energy (DE) computed tomography (CT) urography, and to investigate the feasibility of characterising the calculi through diluted urine. METHODS: Twenty-three urinary calculi were detected in 116 patients who underwent DECT urography for macroscopic haematuria with a split bolus two- or three-acquisition protocol, including a true unenhanced series and at least a mixed nephrographic excretory phase. Virtual unenhanced images were reconstructed from contrast-enhanced DE data. Calculi were recorded on all series and characterised based on their X-ray absorption characteristics at 100 kVp and 140 kVp in both true unenhanced and nephrographic excretory phase series. RESULTS: All calculi with a diameter more than 2 mm were detected in the virtual unenhanced phase and in the nephrographic excretory phase. Thirteen of these calculi could be characterised in the true unenhanced phase and in the mixed nephrographic excretory phase. The results were strictly identical for both phases, six of them being recognised as non-uric acid calculi and seven as uric acid calculi. CONCLUSIONS: Mixed nephrographic excretory phase DECT after furosemide administration allows both detection and characterisation of clinically significant calculi, through the diluted urine. KEY POINTS: • Urinary tract stones can be detected on excretory phase through diluted urine. • Urinary tract stone characterisation with dual-energy CT (DECT) is possible through diluted urine. • A dual energy split-bolus CT urography simultaneously enables urinary stone detection and characterisation.

Diagnosis of urothelial tumors with a dedicated dual-source dual-energy MDCT protocol: preliminary results.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of a dedicated dual-source dual-energy MDCT (DECT) protocol for the detection of urothelial tumors. MATERIALS AND METHODS: A DECT protocol including furosemide and split-bolus contrast injection was used in 69 consecutive patients with suspected abnormalities of the urinary system. Thirteen patients were excluded because there was no follow-up available. In 56 patients, the final diagnosis was proven with endoscopy, biopsy, or follow-up and included urothelial tumors (n = 37) in 16 patients, other urinary tract pathologies (n = 9) in eight patients, and absence of lesions of the collecting system in 32 patients. The image series consisted of a dual-energy true unenhanced series, 35-second arterial phase, and 8-minute nephrographic-excretory phase and were analyzed retrospectively. True enhancement of all detected lesions was measured. On the basis of the DECT data of the contrast-enhanced images, virtual unenhanced series were created and iodine concentration was calculated using commercially available software. The attenuation difference between virtual unenhanced and contrast-enhanced images (virtual enhancement) was measured. CT findings were compared with the final diagnosis. RESULTS: Urothelial tumors were identified on 35-second series, 8-minute series, and both series combined, with sensitivity of 91.9% (95% CI, 78.1-98.2%), 83.4% (68.0-93.8%), and 97.3% (85.8-100%), respectively. Urothelial tumors showed stronger virtual enhancement (p = 0.02) and higher iodine concentration (p = 0.03) than lesions of other origin. Distinction between urothelial tumors and nontumoral lesions was possible with sensitivity of 91.9% (78.1-98.2%) when using a threshold concentration of at least 1.0 mg I/mL. CONCLUSION: Dual phase DECT with virtual unenhanced imaging and iodine concentration measurement appears to be a useful diagnostic test for urothelial tumors.

Liver volume is a prognostic indicator for clinical outcome of patients with alcoholic hepatitis.

PURPOSE: To evaluate the prognostic value of abdominal computed tomography (CT) in patients with alcoholic hepatitis (AH). METHODS: This ancillary study was based on data collected during a previous randomized controlled trial in patients with AH. Clinical response was defined as the improvement of the baseline MELD score ≥3 points at 3 months. All patients underwent contrast-enhanced CT of the abdomen. The following parameters were measured: (1) liver density, spleen density, and liver-to-spleen density ratio; (2) liver-to-body weight (LBW) ratio; and (3) subcutaneous fat, visceral fat, and muscular content. Improvers and non-improvers were compared with univariate, multivariate, and ROC analyses. Results were compared with a validation cohort of patients. RESULTS: Fifty-eight patients (mean age, 56 years) were analyzed, including 34 (59 %) improvers. On multivariate analysis, LBW ratio (OR = 3.73; 95 % CI, 1.65-8.46; p = 0.002) and subcutaneous fat (OR = 1.01; 95 % CI, 1.00-1.02; p = 0.022) were associated with clinical response, with AUROC curves of 0.78 ± 0.06 (p < 0.001) and 0.66 ± 0.07 (p = 0.043), respectively. LBW ≥2.4 % predicted response with 88 % sensitivity and 63 % specificity. In the validation cohort (n = 42, 64 % improvers), the same cut-off value predicted response with 93 % sensitivity and 60 % specificity. CONCLUSIONS: In patients suffering from AH, the liver volume appears to be a major positive prognostic factor.

Incidental adrenal lesions detected on enhanced abdominal dual-energy CT: can the diagnostic workup be shortened by the implementation of virtual unenhanced images?

OBJECTIVE: To determine whether post-processing of the data from portal-phase enhanced dual-energy CT (DECT), with or without the addition of a late enhanced phase acquisition, may enable characterization of adrenal lesions without the need for acquisition of pre-contrast images. MATERIALS AND METHODS: Twenty-two patients with 24 adrenal lesions underwent unenhanced, venous and delayed phase DECT. Of these lesions, 20 were found to be adrenal adenomas, on the basis of histopathology, unenhanced attenuation values between 0 and -10 HU, or stability over at least 6 months. For all 24 lesions, true and virtual unenhanced attenuation values were measured based on the data of the portal (VNCp) and the delayed (VNCd) DECT acquisition. The absolute washout values based on the true non-contrast (TNC) and the VNCp and VNCd image series were also measured. The washout was also calculated based on the iodine concentration measured from both contrast-enhanced acquisitions. RESULTS: Mean virtual unenhanced attenuation values of all lesions calculated from the portal phase images was 12.6 HU, and was 4.02 HU higher than the values based on true unenhanced images (p=0.020). Washout values calculated from virtual unenhanced attenuation based on the VNCp were also significantly different (p=0.0304) while those calculated from VNCd and from iodine concentration correlated with the corresponding values based on the true unenhanced values (p>0.999). CONCLUSIONS: Our data indicate that attenuation values of adrenal adenomas based on virtual unenhanced images are significantly higher than those obtained with true unenhanced images. An incidental adrenal lesion with a virtual unenhanced attenuation lower than 10 HU can thus be safely characterized as an adenoma.