Emre Unal

Imaging of aberrant left gastric vein and associated pseudolesions of segments II and III of the liver and mimickers

We present imaging findings of aberrant left gastric vein (ALGV) and associated pseudolesions and mimickers including metastases and focal nodular hyperplasia. ALGV is formed due to interrupted involution of anastomotic omental veins, and it can drain into left portal vein or segments II and III of the liver as third inflow. Focal fat, focal fat sparing, and perfusion changes can be seen due to the presence of ALGV, which can mimic metastasis in cancer patients. ALGV may also serve as a pathway for direct tumor spread into the liver in patients with gastric cancer. Magnetic resonance imaging can be used as a problem solving tool in the presence of equivocal findings on ultrasonography and computed tomography.

Microvascular invasion in hepatocellular carcinoma.

Microvascular invasion is a crucial histopathologic prognostic factor for hepatocellular carcinoma. We reviewed the literature and aimed to draw attention to clinicopathologic and imaging findings that may predict the presence of microvascular invasion in hepatocellular carcinoma. Imaging findings suggesting microvascular invasion are disruption of capsule, irregular tumor margin, peritumoral enhancement, multifocal tumor, increased tumor size, and increased glucose metabolism on positron emission tomography-computed tomography. In the presence of typical findings, microvascular invasion may be predicted.

Nonthrombotic Pulmonary Artery Embolism: Imaging Findings and Review of the Literature

OBJECTIVE The purpose of this article is to emphasize the imaging findings encountered in the setting of nonthrombotic pulmonary embolism. CONCLUSION Nonthrombotic pulmonary embolism refers to a spectrum of clinical and radiologic disorders caused by embolization of the pulmonary artery vasculature by various cell types, microorganism, and foreign bodies. Awareness of the imaging and clinical features of the nonthrombotic pulmonary embolism may facilitate prompt diagnosis.

Invisible fat on CT: making it visible by MRI.

Presence of fat in a lesion significantly narrows the differential diagnosis. Small quantities of macroscopic fat and intracellular fat are invisible on computed tomography (CT) and ultrasonography. Magnetic resonance imaging (MRI) can reveal any fatty change in a lesion and can also differentiate macroscopic fat from intracellular and intravoxel fat. Hypodensity on CT may be a sign of invisible fat and MRI can help to diagnose even minute amounts of fat in liver, pancreas, adrenal, musculoskeletal, and omental pseudolesions and lesions. This article will review the superiority of MRI over CT in demonstrating fat in abdominal lesions.

Comparison of image quality and radiation dose between prospectively ECG-triggered and retrospectively ECG-gated CT angiography: Establishing heart rate cut-off values in first-generation dual-source CT.

Objective: To evaluate radiation dose and image quality of prospectively electrocardiography (ECG)-triggered and retrospectively ECG-gated coronary computed tomography (CT) angiography and to establish cut-off values of heart rates (HRs) for each technique in firstgeneration dual-source CT. Methods: A total of 200 consecutive patients with suspected coronary artery disease were accepted into the study. Patients were selected randomly for each technique (prospective triggering group n=99, mean age 55.85±10.74 and retrospective gating group n=101, mean age 53.38±11.58). Two independent radiologists scored coronary artery segments for image quality using a 5-point scale. Also, attenuation values of each coronary artery segment and dose-length product values were measured. For each technique, cut-off HR values were determined for the best image quality. Results: Mean image quality scores and attenuation values were found to be higher in the prospective triggering group (p<0.05). Mean radiation dose was 73% lower for the prospective triggering group (p<0.01). The cut-off HR values for good image quality scores were ≤67 beats per minute (bpm) and ≤80 bpm for the prospective triggering and retrospective gating groups, respectively (p<0.05). Increased HR (≥68 and ≥81 bpm, respectively) had negative effects on image quality (p<0.05). Conclusion: The prospective ECG triggering technique has better image quality scores than retrospective ECG gating, particularly in patients who have an HR of less than 68 bpm. Also, a 73% radiation dose reduction can be achieved with prospective ECG triggering. In patients with higher heart rates, retrospective ECG gating is recommended.

Imaging findings of splenic emergencies: a pictorial review.

Although traumatic injuries are the cause of common splenic emergencies in the emergency room, various nontraumatic conditions may also affect the spleen with possible life-threatening results. In this pictorial review, we present imaging findings of usual and unusual splenic emergencies. It is essential to be familiar with key imaging findings and advantages of different modalities to reach a definitive diagnosis.Teaching points• Delayed splenic rupture is commonly related to subcapsular hematoma.• Subtle haemorrhage is commonly restricted to the site of injury “sentinel clot sign”.• The whorled appearance is the key imaging feature of splenic torsion.

Liver Function Assessment by Magnetic Resonance Imaging

Liver function assessment by hepatocyte-specific contrast-enhanced magnetic resonance imaging is becoming a new biomarker. Liver function can be assessed by T1 mapping (reduction rate) and signal intensity measurement (relative enhancement ratio) before and after GD-EOB-DTPA (gadoxetic acid) administration, as alternative to Tc-99m galactosyl serum albumin scintigraphy, 99m Tc-labeled mebrofenin scintigraphy, and indocyanine green clearance test. Magnetic resonance imaging assessment of liver function can enable diagnosis of cirrhosis, nonalcoholic fatty liver disease associated fibrosis and steatohepatitis, primary sclerosing cholangitis, toxic hepatitis, and chemotherapy and radiotherapy-related changes, which may be only visible on hepatobiliary phase images. Simple visual assessment of signal intensity at hepatobiliary phase images is important for the diagnosis of different patterns of liver dysfunction including diffuse, lobar, segmental, and subsegmental forms. Furthermore, preoperative assessment of liver function is feasible before oncologic hepatic surgery, which may be important to prevent posthepatectomy liver failure and to estimate future remnant volume. Functional magnetic resonance cholangiography obtained by T1-weighted images at hepatobiliary phase can allow diagnosis of acalculous cholecystitis, biliary leakage, bile reflux to the stomach, sphincter of oddi dysfunction, and lesions with communication to biliary tree. Functional information can be easily obtained when Gd-EOB-DTPA is used for liver magnetic resonance imaging.

Primary retroperitoneal fasciitis; A rare cause of acute abdominal pain

The retroperitoneal fascial planes can be affected by various clinical disorders. In most of the cases retroperitoneal involvement occurs secondary to spread of a distinct underlying etiology. Herein we report two cases of primary retroperitoneal fasciitis diagnosed with imaging findings. The diagnosis of retroperitoneal fasciitis should be made by exclusion since various and more frequently encountered disorders including acute pancreatitis, duodenitis, pyelonephritis, and appendicitis may present with similar imaging findings.

Computed Tomography-Based Diagnosis of Gastric Vein Invasion in Patients with Gastric Cancer

Objective The objective of this study was to demonstrate computed tomography (CT)-based diagnosis of venous invasion in patients with gastric cancer and its prognostic value. Materials and Methods Medical records and CT examinations of 530 patients with gastric cancer diagnosed after biopsy from February 2003 to December 2015 were included in this retrospective study. An imaging-based diagnosis of venous invasion was established when one of the following criteria were satisfied: 1) tumoral enhancement in the lumen of the vein, 2) tumor protruding through the course of a vein, and 3) distention of the vein due to extension of the gastric tumor. CT-based diagnosis of gastric vein invasion was established in 11/530 patients. Results Histopathological examination revealed poorly differentiated gastric adenocarcinoma (n=10) and neuroendocrine carcinoma (n=1). The median survival of the patients after the initial CT was 153.5 (range: 6-1275) days. Tumor invasion was observed at the aberrant left gastric vein (n=2), right gastroepiploic and superior mesenteric vein (n=2), gastric vein (n=4), and short gastric vein (n=3). Two of the three patients with short gastric vein invasion died 6 and 7 days after the initial CT, respectively. Conclusion All draining veins of the stomach can be invaded by gastric cancer; CT can enable diagnosis that may be important for prognosis and surgical planning. The presence of short gastric vein invasion detected by CT may be associated with poor prognosis.

Hepatobiliary phase liver MR imaging findings after Oxaliplatin-based chemotherapy in cancer patients.

ObjectiveTo describe Gd-EOB-DTPA-enhanced liver MR imaging findings in colon and rectal cancer patients who received Oxaliplatin.ConclusionSpectrum of hepatobiliary phase imaging findings include diffuse heterogeneous dysfunction, macronodular and micronodular FNH-like lesions, and coexistence of periportal increased liver function with FNH-like lesions. Differentiation of these benign lesions from metastasis is crucial to avoid biopsy in patients with colorectal cancers and may allow better understanding of sinusoidal obstruction syndrome pathophysiology and regenerative response of liver.