Unveiling the unreal: Comprehensive imaging review of hepatic pseudolesions.

Hepatic pseudolesions are defined as non-neoplastic focal abnormalities of the liver which can mimic or conceal true liver lesions. It is particularly common in liver due to its unique dual blood supply and the existence of multilevel anastomosis between them. Because of the recent advances in CT and MRI technology, they are being increasingly encountered in daily practice. Broadly they can be categorised in to (1) Focal parenchymal abnormalities like focal fatty change, focal fat sparing, focal confluent fibrosis, segmental hypertrophy and regenerative nodules, (2) Perfusion abnormalities which include transient hepatic parenchymal enhancement in portal vein obstruction, third inflow, intrahepatic shunts, hepatic arterial occlusion and hepatic venous obstruction, (3) Imaging pitfalls like parenchymal compression, unenhanced vessels and pseudolipoma. It is essential for the radiologists to be familiar with the typical and atypical imaging features of pseudolesions to avoid mistaking them for sinister pathologies and also to avoid overlooking underlying hidden pathologies.

Beyond ureterolithiasis: gamut of abnormalities affecting the ureter.

Nephrolithiasis is the most common condition involving the ureters. However, various other entities can affect the ureters, albeit less frequently. Imaging plays a crucial role in diagnosis, management, and follow-up of ureteral pathology. In the past decade, computed tomography urography has replaced traditional methods of ureteral imaging due to its high spatial resolution, multiplanar imaging, and rapid acquisition time. More recently, magnetic resonance urography has also been explored in evaluating ureteral abnormalities. In this review, we briefly discuss current imaging techniques used in assessment of the ureters and present a diverse group of diseases affecting the ureters. We begin with primary and secondary ureteral malignancies, followed by uncommon infectious/inflammatory diseases that can involve the ureters including tuberculosis, xanthogranulomatous pyelonephritis, and graft-versus-host disease. We then discuss the imaging characteristics of endometriosis and retroperitoneal fibrosis as two important examples of pelvic and retroperitoneal processes that occasionally obstruct the ureters and present with clinical symptoms similar to that of renal stones. We end with a brief discussion of miscellaneous conditions that affect the ureters, including ureteral hemorrhage, ureteral intussusception, ureteral pseudodiverticulosis, Malacoplakia, and ureteritis cystica. Knowledge of these entities and their characteristic imaging manifestations along with patient's clinical presentation allows accurate diagnosis and timely patient management.

Multi-modality imaging review of congenital abnormalities of kidney and upper urinary tract.

Congenital abnormalities of the kidney and urinary tract (CAKUT) include a wide range of abnormalities ranging from asymptomatic ectopic kidneys to life threatening renal agenesis (bilateral). Many of them are detected in the antenatal or immediate postnatal with a significant proportion identified in the adult population with varying degree of severity. CAKUT can be classified on embryological basis in to abnormalities in the renal parenchymal development, aberrant embryonic migration and abnormalities of the collecting system. Renal parenchymal abnormalities include multi cystic dysplastic kidneys, renal hypoplasia, number (agenesis or supernumerary), shape and cystic renal diseases. Aberrant embryonic migration encompasses abnormal location and fusion anomalies. Collecting system abnormalities include duplex kidneys and Pelvi ureteric junction obstruction. Ultrasonography (US) is typically the first imaging performed as it is easily available, non-invasive and radiation free used both antenatally and postnatally. Computed tomography (CT) and magnetic resonance imaging (MRI) are useful to confirm the ultrasound detected abnormality, detection of complex malformations, demonstration of collecting system and vascular anatomy and more importantly for early detection of complications like renal calculi, infection and malignancies. As CAKUT are one of the leading causes of end stage renal disease, it is important for the radiologists to be familiar with the varying imaging appearances of CAKUT on US, CT and MRI, thereby helping in prompt diagnosis and optimal management.

Multi detector CT Imaging of Abdominal and Diaphragmatic Hernias: Pictorial Essay.

Diagnosis of abdominal wall hernia is often a clinical problem, especially in occult or in obese patients. Multidetector CT is an accurate method of detecting various types of abdominal and diaphragmatic hernias. It clearly demonstrates the anatomical sites of hernial sac, its contents and possible complications.

Current updates on the molecular genetics and magnetic resonance imaging of focal nodular hyperplasia and hepatocellular adenoma.

UNLABELLED: Focal nodular hyperplasia (FNH) and hepatocellular adenomas (HCAs) constitute benign hepatic neoplasms in adults. HCAs are monoclonal neoplasms characterised by an increased predilection to haemorrhage and also malignant transformation. On the other hand, FNH is a polyclonal tumour-like lesion that occurs in response to increased perfusion and has an uneventful clinical course. Recent advances in molecular genetics and genotype-phenotype correlation in these hepatocellular neoplasms have enabled a new classification system. FNHs are classified into the typical and atypical types based on histomorphological and imaging features. HCAs have been categorised into four subtypes: (1) HCAs with HNF-1α mutations are diffusely steatotic, do not undergo malignant transformation, and are associated with familial diabetes or adenomatosis. (2) Inflammatory HCAs are hypervascular with marked peliosis and a tendency to bleed. They are associated with obesity, alcohol and hepatic steatosis. (3) HCAs with ß-catenin mutations are associated with male hormone administration and glycogen storage disease, frequently undergo malignant transformation and may simulate hepatocellular carcinoma on imaging. (4) The final type is unclassified HCAs. Each of these except the unclassified subtype has a few distinct imaging features, often enabling reasonably accurate diagnosis. Biopsy with immunohistochemical analysis is helpful in difficult cases and has strong implications for patient management. TEACHING POINTS: • FNHs are benign polyclonal neoplasms with no risk of haemorrhage or malignancy. • HCAs are benign monoclonal neoplasms classified into four subtypes based on immunohistochemistry. • Inflammatory HCAs show an atoll sign with a risk of bleeding and malignant transformation. • HNF-1α HCAs are steatotic HCAs with minimal complications and the best prognosis. • ß-Catenin HCA shows variable MRI features and a high risk of malignancy.

What is hiding in the hindgut sac? Looking beyond rectal carcinoma.

OBJECTIVES: Although rectal cancer is by far and large the most common pathology involving the rectum that needs imaging, there are many other important but less common pathological conditions affecting anorectal region. The objective of this pictorial review is to discuss the cross-sectional imaging features of less common anorectal and perirectal diseases. RESULTS: Although a specific histological diagnosis cannot usually be made due to considerable overlap in the imaging appearances of anorectal diseases, this review illustrates the cross-sectional imaging findings with emphasis on magnetic resonance imaging (MRI) that can help in narrowing down the differentials to a reasonable extent. TEACHING POINTS: • Variety of pathology exists in the anorectum apart from common rectal carcinoma • Anorectal diseases present as non-specific wall thickening indistinguishable from rectal carcinoma • Computed tomography (CT) and MRI can help in narrowing down the differentials, although often biopsy is warranted.

Chronic rupture of abdominal aortic aneurysm with vertebral erosion: an uncommon but important cause of back pain.

Chronic contained rupture of the aorta is a rare condition that may present with varied patient symptomatology. We present a case of contained rupture of an abdominal aortic aneurysm causing vertebral erosion in an elderly male patient who had chronic backache and presented to the emergency services with a recently developed throbbing epigastric mass. Early use of computed tomography enabled prompt diagnosis and the condition was managed by endovascular stenting. The clinical and imaging findings of this potentially fatal condition are described, awareness of which is important to the physicians, orthopedicians, surgeons, and radiologists.

Diagnostic accuracy of dual-echo (in- and opposed-phase) T1-weighted gradient recalled echo for detection and grading of hepatic iron using quantitative and visual assessment.

OBJECTIVES: Detection and quantification of hepatic iron with dual-echo gradient recalled echo (GRE) has been proposed as a rapid alternative to other magnetic resonance imaging (MRI) techniques. Co-existing steatosis and T1 weighting are limitations. This study assesses the accuracy of routine dual-echo GRE. METHODOLOGY: Between 2010 and 2013, 109 consecutive patients underwent multi-echo (ME) MRI and dual-echo GRE for quantification of hepatic iron. Liver iron concentration (LIC) was calculated from ME-MRI. Relative signal intensity (RSI) and fat signal fraction (FSF) were calculated from dual-echo GRE. Four radiologists subjectively evaluated dual-echo GRE (±subtraction). Diagnostic accuracy was compared between techniques and correlated with biopsy using Fisher's exact test, Spearman correlation and regression. RESULTS: The sensitivity of visual detection of iron ranged from 48 to 55%. Subtraction did not increase sensitivity (p < 0.001). Inter-observer variability was substantial (κ = 0.72). The specificity of visual detection of iron approached 100% with false-positive diagnoses observed using subtraction. LIC showed a higher correlation with histopathological iron grade (r = 0.94, p < 0.001) compared with RSI (r = 0.65, p = 0.02). Univariate regression showed an association between RSI and LIC (B = 0.98, p < 0.001, CI 0.73-1.23); however, the association was not significant with multi-variate regression including FSF (p = 0.28). CONCLUSIONS: Dual-echo GRE has low sensitivity for hepatic iron. Subtraction imaging can result in false-positive diagnoses. KEY POINTS: • Routine liver MRI studies cannot effectively screen patients for iron overload. • Concomitant hepatic steatosis and iron limits diagnostic accuracy of routine liver MRI. • Dual-echo GRE subtraction imaging causes false-positive diagnoses of iron overload. • Dedicated MRI techniques should be used to diagnose and quantify iron overload.