Respiratory-motion artefacts in liver MRI following injection of gadoxetate disodium and gadobenate dimeglumine: an intra-individual comparative study in cirrhotic patients.

AIM: To perform an intra-individual comparison of the frequency of respiratory-motion artefacts on magnetic resonance imaging (MRI) in cirrhotic patients following injection of gadoxetate disodium and gadobenate dimeglumine. MATERIALS AND METHODS: Ninety-five cirrhotic patients (61 men and 34 women, mean age 58 years) underwent liver MRI with intravenous administration of gadoxetate disodium and gadobenate dimeglumine at different times (interval between studies, 189±83 days). Three readers scored the severity of respiratory-motion artefacts on the three-dimensional (3D) gradient-echo (GRE) images acquired before and after contrast medium injection. McNemar's test was used to assess the difference in frequency of new respiratory-motion artefacts and transient severe motion (TSM) artefacts between gadoxetate disodium and gadobenate dimeglumine MRI studies. The association between clinical and technical features and the occurrence of TSM on gadoxetate disodium MRI studies was investigated. RESULTS: On arterial phase images, new respiratory-motion artefacts were present in 32/95 (34%) cases after injection of gadoxetate disodium, while only seen in 2/95 (2%) cases after injection of gadobenate dimeglumine (p<0.0001). TSM was present in 6/95 (6%) cases after injection of gadoxetate disodium, and in 0/95 (0%) case after injection of gadobenate dimeglumine. No clinical or technical features were associated with the occurrence of TSM. CONCLUSIONS: In cirrhotic patients, respiratory-motion artefacts on arterial phase 3D GRE images are more frequently seen after injection of gadoxetate disodium than after injection of gadobenate dimeglumine.

Dieulafoy lesion: CT diagnosis of this lesser-known cause of gastrointestinal bleeding.

A Dieulafoy lesion describes a tortuous, submucosal artery in the gastrointestinal tract--most commonly the posterior stomach--that penetrates through the mucosa over time, eventually perforating to cause severe gastrointestinal bleeding. Due to its insidious onset, tendency to cause intermittent but severe bleeding, and difficulty of endoscopic diagnosis, Dieulafoy lesion has a very high mortality rate. Although originally thought not to be a radiologically diagnosable entity, Dieulafoy lesions can be seen at enhanced CT of the abdomen. The purpose of this review is to summarize the pathophysiology, epidemiology, diagnosis, and management of Dieulafoy lesions with a focus on diagnostic findings at enhanced CT imaging.

MDCT of acute conditions affecting the mesenteric vasculature.

Acute conditions affecting the mesenteric vessels can cause abdominal pain and result in significant morbidity and mortality if not diagnosed and treated quickly. As bowel viability depends on patency of the mesenteric vessels, prompt diagnosis is essential. Helical multidetector computed tomography (MDCT) provides a rapid, widely available, non-invasive method to promptly evaluate the mesenteric arteries, veins, and abdominopelvic viscera. Given the value of MDCT in diagnosing vascular disease, it is important the radiologist understand technical and imaging findings of mesenteric vascular injury. Therefore, successful diagnosis hinges on familiarity with MDCT angiography and the extended capabilities of volume rendering and multiplanar reformation. In this review, we illustrate and describe key MDCT findings of congenital, inflammatory, traumatic, infectious, and thromboembolic conditions affecting the mesenteric vasculature in adult patients.

Duodenum: MDCT of acute conditions.

Multidetector computed tomography (MDCT) is the technique of choice for evaluating patients with acute abdominal pain. As the jejunum, ileum, and colon comprise the majority of the gastrointestinal tract, radiologists may potentially neglect the duodenum. However, the duodenum is a complex structure that can be affected by both intraperitoneal and extraperitoneal processes due to its central location and proximity to numerous upper abdominal structures. In this review, the MDCT findings of various congenital, inflammatory, traumatic, infectious, vascular, and miscellaneous conditions that affect the duodenum are discussed.

Neoplastic and proliferative disorders of the perinephric space.

The perinephric space is a well-marginated central compartment of the retroperitoneum, located between the anterior and posterior pararenal spaces. Various neoplastic and proliferative disorders can affect the perinephric space, and there is a wide array of imaging findings. Although many perinephric lesions may extend directly from the kidney and adrenal gland, other lesions occur in the perinephric space due to haematogenous spread, as part of a systemic disease, or by extension from an adjacent retroperitoneal compartment. Imaging plays a pivotal role in the diagnosis of perinephric diseases, as many of the disease processes affecting this space will not result in clinical signs or symptoms until the disease is at an advanced stage. Despite the often shared non-specific clinical and imaging findings among these disease processes, application of a categorical differential diagnosis based on the imaging characteristics will serve to narrow the differential diagnosis and direct further evaluation and treatment. In this article, the lesions have been categorized as soft-tissue rind [nephroblastomatosis, fibrosis, Erdheim-Chester disease (ECD), extramedullary haematopoiesis, lymphoma, infiltrating metastases], focal solid lesions (extension of renal or adrenal malignancies, melanoma metastases, treated lymphoma), fat-containing lesions (angiomyolipoma, liposarcoma, myelolipoma), and cystic lesions (lymphangiomas, abscesses). The aim of this article is to demonstrate and describe the key imaging features of several neoplastic and proliferative disorders that affect the perinephric space.

Superphysiologic FDG Uptake in the Non-Paralyzed Vocal Cord. Resolution of a False-Positive PET Result with Combined PET-CT Imaging.

The application of positron emission tomography imaging with 18F-fluorodeoxyglucose (FDG) to the extracranial head and neck has been proven to be effective in the detection and staging of malignancy. The FDG uptake of normal laryngeal tissue is symmetric and low, while benign lesions typically have only slight increases in FDG uptake. We report a case of asymmetric, superphysiologic FDG uptake in the contralateral vocal cord of a patient with a unilateral vocal cord paralysis secondary to sacrifice of the recurrent laryngeal nerve during pneumonectomy for lung cancer. The FDG uptake of the non-paralyzed vocal cord was increased multiple-fold, placing it well within the range of malignancy. Use of unique, combined PET-CT imaging localized the high FDG uptake to the non-paralyzed vocal cord, and laryngoscopy confirmed no evidence of malignancy in the vocal cord. This case demonstrates that a benign cause of false-positive FDG-PET imaging may be encountered during evaluation of the extracranial head and neck for malignancy. We aim to alert the reader to this potential pitfall in the interpretation of FDG-PET imaging, which can be resolved with the use of combined PET-CT imaging and clinical correlation.