Subramaniyan Ramanathan

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.

Complications of minimally invasive procedures of the abdomen and pelvis: a comprehensive update on the clinical and imaging features

Minimally invasive gastrointestinal, genitourinary, and gynecological procedures are widely used in the clinical practice for diagnostic and therapeutic purposes. Complications both minor and major are not uncommon with these procedures. Imaging plays an important role in the detection and optimal management of these complications. Familiarity with the clinical and imaging features of these complications by radiologists can help in their timely detection.

Gastroenterology: Revisiting the forgotten sign: Five layered gut signature and Y configuration in enteric duplication cysts on high resolution ultrasound

A 3-month-old female child presented with 3-week history of difficulty in passing stools, decreasing bowel movements, progressive abdominal distention and bilious vomiting in the last five days. Antenatal ultrasound in the 3rd trimester showed cystic lesion in the right lower abdomen close to urinary bladder and possibility of ovarian cyst was suggested. On physical examination, increasing abdominal girth and mild dehydration was observed. Laboratory investigation was within normal range. Clinical diagnosis of intestinal obstruction was made and ultrasound abdomen was requested. Ultrasound showed a cystic lesion, measuring 3.8 × 3.7 × 5 cm in right lower quadrant, adherent to a markedly dilated bowel loop (Fig. 1a). “Double wall sign” was seen representing inner hyperechoic mucosa and outer hypoechoic muscular layer (Fig. 1b). Double wall sign is typically seen in enteric duplication cysts and was further confirmed by high resolution ultrasound which showed multilayered (Five layers) appearance and splitting and continuation of hypoechoic muscular layer with the adjacent bowel loop (Y configuration) (Fig. 2a). Immediate exploratory laparotomy was performed which showed cyst at the ileocecal region adherent to terminal ileum. Ileocecal resection with primary anastomosis was performed without complications. Histopathological examination was consistent with ileal duplication cyst (Fig 2b). Duplication cysts are rare congenital anomalies and can involve any part of gastrointestinal tract from esophagus to rectum with approximate distribution of 50% involving the midgut, 36% foregut, and 12% the hindgut. Ileal duplication cysts are the commonest and constitute 35% of midgut duplications. The clinical presentation of enteric duplication cyst is variable depending on the size, site and the mucosal lining. They can be asymptomatic or associated with nonspecific abdominal pain, constipation, vomiting, hemorrhage and intestinal obstruction as in our index case. Ultrasound is used routinely in pediatric population with abdominal complaints. Common differential diagnosis for abdominal cystic lesions in children are mesenteric or omental cysts, ovarian cysts, duplication cyst, choledochal cyst, hydronephrosis, pseudocyst and rarely Meckel’s diverticulum and cystic tumours. Classical findings of uncomplicated duplication cyst include cyst in relation to gut with double wall or muscular rim sign which is caused by inner hyperechoic mucosa and outer hypoechoic muscularis propria. Initially this sign was thought to be very specific which would obviate the need for extensive differential for cystic masses. However many scattered case reports questioned the reliability of this sign as other lesions like mesenteric cyst, Meckel’s diverticulum and torted ovarian cyst also demonstrated the double wall sign. A new sign “Five layered cyst wall” was then proposed which correspond to innermost hyperechoic mucosa, hypoechoic muscularis mucosa, hyperechoic submucosa, hypoechoic muscularis propria and outermost hyperechoic serosa. This is pathognomic of duplication cyst. However, this sign is difficult to demonstrate and needs expertise and high-resolution real-time linear ultrasound. Complicated duplication cyst rarely presents with classic five layers or double wall sign due to destruction of mucosa and submucosa. In such cases the relation with the gut and the continuation of muscularis propria of the cyst wall with the gut creating “Y configuration” are the differential key points, that may help in establishing the correct diagnosis.

Large Bowel Obstruction in the Emergency Department: Imaging Spectrum of Common and Uncommon Causes

Although large bowel obstruction (LBO) is less common than small bowel obstruction, it is associated with high morbidity and mortality due to delayed diagnosis and/or treatment. Plain radiographs are sufficient to diagnose LBO in a majority of patients. However, further evaluation with multidetector computed tomography (MDCT) has become the standard of care to identify the site, severity, and etiology of obstruction. In this comprehensive review, we illustrate the various causes of LBO emphasizing the role of MDCT in the initial diagnosis and detection of complications along with the tips to differentiate from disease which can mimic LBO.

Faecolith migrating from the appendix to produce liver abscess after subhepatic laparoscopic appendectomy

The subhepatic position of an appendix may lead to difficulty in diagnosis of appendicitis, its surgical management as well as bizarre complications. A ‘lost’ appendicular faecolith is not an uncommon complication due to spillage during the removal of the appendix or due to perforation. Here we report a case of such a faecolith migrating into the liver parenchyma following intraoperative hepatic injury, and producing a liver abscess. The calcified lesion seen in the liver corresponded to a free-lying faecolith on a preoperative computed tomography scan. Liver abscess was presumed to arise from implantation of this foreign object into the liver parenchyma. Pigtail drainage of abscess was performed with good result.

Bithalamic T2 hypointensity: a diagnostic clue for Sandhoff's disease.

A 6‐month male child with uneventful perinatal history presented with developmental delay, poor visual contact and psychomotor regression. On neurological examination, he was hypertonic with brisk deep tendon reflexes and exaggerated startle reflex. Fundoscopic examination revealed cherry‐red spot in both the eyes. There was family history of neurometabolic disease in a cousin. Magnetic resonance imaging (MRI) brain demonstrated bilateral symmetrical T2 hypointensity and T1 hyperintensity involving the thalamus. Bilateral basal ganglia appeared swollen with subtle T2 hyperintensity of putamen. Bilateral cerebral white matter showed diffuse symmetric T2 hyperintensity suggesting delayed myelination [Figures 1 and 2]. Corpus callosum was thinned out [Figure 3]. No significant cortical atrophy, brainstem or cerebellar abnormalities identified. Enzymatic assay revealed deficiency of both hexosaminidases A and B confirming the diagnosis of Sandhoff’s disease.

Magnetic resonance imaging (MRI) of the renal sinus

This article presents methods to improve MR imaging approach of disorders of the renal sinus which are relatively uncommon and can be technically challenging. Multi-planar Single-shot T2-weighted (T2W) Fast Spin-Echo sequences are recommended to optimally assess anatomic relations of disease. Multi-planar 3D-T1W Gradient Recalled Echo imaging before and after Gadolinium administration depicts the presence and type of enhancement and relation to arterial, venous, and collecting system structures. To improve urographic phase MRI, concentrated Gadolinium in the collecting systems should be diluted. Diffusion-Weighted Imaging (DWI) should be performed before Gadolinium administration to minimize T2* effects. Renal sinus cysts are common but can occasionally be confused for dilated collecting system or calyceal diverticula, with the latter communicating with the collecting system and filling on urographic phase imaging. Vascular lesions (e.g., aneurysm, fistulas) may mimic cystic (or solid) lesions on non-enhanced MRI but can be suspected by noting similar signal intensity to the blood pool and diagnosis can be confirmed with MR angiogram/venogram. Multilocular cystic nephroma commonly extends to the renal sinus, however, to date are indistinguishable from cystic renal cell carcinoma (RCC). Solid hilar tumors are most commonly RCC and urothelial cell carcinoma (UCC). Hilar RCC are heterogeneous, hypervascular with epicenter in the renal cortex compared to UCC which are centered in the collecting system, homogeneously hypovascular, and show profound restricted diffusion. Diagnosis of renal sinus invasion in RCC is critically important as it is the most common imaging cause of pre-operative under-staging of disease. Fat is a normal component of the renal sinus; however, amount of sinus fat correlates with cardiovascular disease and is also seen in lipomatosis. Fat-containing hilar lesions include lipomas, angiomyolipomas, and less commonly other tumors which engulf sinus fat. Mesenchymal hilar tumors are rare. MR imaging diagnosis is generally not possible, although anatomic relations should be described to guide diagnosis by percutaneous biopsy or surgery.

Sonography of Scrotal Wall Lesions and Correlation With Other Modalities

The scrotal wall may be involved in a variety of pathologic processes. Such lesions may rise primarily from the layers of the scrotum or may be due to a process arising from scrotal content. Imaging is not needed in most cases, but it may be useful for making such differentiations and for evaluation of possible involvement of the testes and epididymides in cases of primary wall abnormalities. This pictorial essay will show the imaging findings observed in a variety of pathologic conditions affecting the scrotal wall, both common and unusual ones, with an emphasis on clinically relevant findings and features that lead to a specific diagnosis.

CNS aspergilloma mimicking tumors: Review of CNS aspergillus infection imaging characteristics in the immunocompetent population

BACKGROUND AND PURPOSE CNS Aspergillosis is very rare and difficult to diagnose clinically and on imaging. Our objective was to elucidate distinct neuroimaging pattern of CNS aspergillosis in the immunocompetent population that helps to differentiate from other differential diagnosis. METHODS Retrospective analysis of brain imaging findings was performed in eight proven cases of central nervous system aspergillosis in immunocompetent patients. Immunocompetent status was screened with clinical and radiological information. Cases were evaluated for anatomical distribution, T1 and T2 signal pattern in MRI and attenuation characteristics in CT scan, post-contrast enhancement pattern, internal inhomogeneity, vascular involvement, calvarial involvement and concomitant paranasal, cavernous sinus or orbital extension. All patients were operated and diagnosis was confirmed on histopathology. RESULTS The age range was 19-50 years with mean age of 33.7 years. Concomitant sinonasal disease was seen in six patients (75%). Three patients had orbital extensions. Most of the lesions (n=7) were profoundly hypointense in T2-weighted imaging. The most common enhancement pattern was bright, solid and homogenous enhancement (n=7). Cavernous extension with ICA encasement was always associated with paranasal sinus disease. Six patients showed demineralization or complete resorption of involved bone. All of the fungal masses appear hyperdense on available CT scan images. CONCLUSION CNS aspergillus infection in immunocompetent patients has distinct imaging features as compared to CNS aspergillosis in immunocompromised patients. A high index of suspicion in proper clinical settings, even with immunocompetent status and typical imaging features allow us to diagnose CNS aspergillosis in such patients.

Crossing the canal: Looking beyond hernias — Spectrum of common, uncommon and atypical pathologies in the inguinal canal

Inguinal canal can have diverse range of pathologies due to its complex anatomy and multiple different contents in the males and females. Imaging plays a dominant role in the appropriate diagnosis and management as inguinal pathologies have fairly similar clinical presentation with pain and swelling. Various pathologies in the inguinal region include congenital, infectious/inflammatory, vascular, neoplastic and iatrogenic. This paper gives an overview of the role of various modalities like Ultrasound, CT and MRI in the evaluation of inguinal pathologies.