Portosystemic shunts are enlarged vessels that form collateral pathological pathways between the splanchnic circulation and the systemic circulation. Although their causes are multifactorial, portosystemic shunts all have one mechanism in common—increased portal venous pressure, which diverts the blood flow from the gastrointestinal tract to the systemic circulation. Congenital and acquired collateral pathways have both been described in the literature. The aim of this pictorial essay was to discuss the distinct anatomic and imaging features of portosystemic shunts, as well as to provide a robust method of differentiating between acquired portosystemic shunts and similar pathologies, through the use of illustrations and schematic drawings. Imaging of portosystemic shunts provides subclinical markers of increased portal venous pressure. Therefore, radiologists play a crucial role in the identification of portosystemic shunts. Early detection of portosystemic shunts can allow ample time to perform endovascular shunt operations, which can relieve portal hypertension and prevent acute or chronic complications in at-risk patient populations.

Keywords: Collateral circulation; Splanchnic circulation; Hypertension, portal/complications.

OBJECTIVE: To assess the feasibility and reliability of apparent diffusion coefficient (ADC) measurements of normal adrenal glands. MATERIALS AND METHODS: This was a retrospective study involving 32 healthy subjects, divided into two groups: prepubertal (PreP, n = 12), aged from 2 months to 12.5 years (4 males; 8 females); and postpubertal (PostP, n = 20), aged from 11.9 to 61 years (5 males; 15 females). Diffusion-weighted magnetic resonance imaging (DW-MRI) sequences were acquired at a 1.5 T scanner using b values of 0, 20, 500, and 1000 s/mm². Two radiologists evaluated the images. ADC values were measured pixel-by-pixel on DW-MRI scans, and automatic co-registration with the ADC map was obtained. RESULTS: Mean ADC values for the right adrenal glands were 1.44 × 10^–3 mm²/s for the PreP group and 1.23 × 10^–3 mm²/s for the PostP group, whereas they were 1.58 × 10^–3 mm²/s and 1.32 × 10^–3 mm²/s, respectively, for the left glands. ADC values were higher in the PreP group than in the PostP group (p < 0.05). Agreement between readers was almost perfect (intraclass correlation coefficient, 0.84–0.94; p < 0.05). CONCLUSION: Our results demonstrate the feasibility and reliability of performing DW-MRI measurements of normal adrenal glands. They could also support the feasibility of ADC measurements of small structures.

Keywords: Adrenal glands; Diffusion magnetic resonance imaging; Magnetic resonance imaging.

Adnexal torsion is characterized by partial or complete rotation of the suspensory ligament of the ovary and its corresponding vascular pedicle, resulting in vascular impairment that can culminate in hemorrhagic infarction, as well as necrosis of the ovary and fallopian tube. Because there are myriad causes of acute pelvic pain, the differential diagnosis of ovarian torsion is often challenging. Consequently, radiologists should be familiar with the main imaging findings. In this regard, there are typical signs of ovarian torsion on magnetic resonance imaging, including increased ovarian volume with stromal edema and peripheral distribution of the ovarian follicles, as well as thickening of the fallopian tube, an adnexal mass (causal factor) that shifts toward the midline, and the classic, pathognomonic “whirlpool sign”. The objective of this essay was to review and illustrate the various magnetic resonance imaging findings in ovarian torsion.

Keywords: Magnetic resonance imaging; Ovary; Torsion abnormality; Ovarian neoplasms; Ovarian cysts.

Portal vein thrombosis refers to complete or partial obstruction of the portal venous system, in the intrahepatic or extrahepatic venous tract or even in the splenic or superior mesenteric veins. This common and potentially fatal condition can develop in various clinical contexts, especially those of liver cirrhosis, hepatocellular carcinoma, and other solid tumors. Certain characteristics, such as the time since the onset of the thrombus (acute or chronic), its biology (hematic or tumoral), the presence of collateral vessels, and the magnetic resonance imaging aspects, are important components of a thorough, careful analysis, as well as informing decisions regarding the appropriate therapeutic strategy. Here, we present a brief review of the anatomy of the portal venous system and a systematic approach to analyzing the condition, using a mnemonic (ABCD, for age, biology, collaterals, and diffusion). We discuss the various imaging methods and illustrate our discussion with images selected from the case files archived at our facility.

Keywords: Portal vein; Venous thrombosis; Hypertension, portal; Collateral circulation; Magnetic resonance imaging.

Pancreas transplantation is a well-established treatment for patients with complicated diabetes mellitus and advanced renal failure. The most common procedure is simultaneous pancreas-kidney transplantation, in which the pancreas graft is positioned in the right pelvic region and the kidney graft is positioned in the left iliac fossa. Various imaging methods are used for the post-transplantation evaluation of the graft parenchyma and vascular anatomy, as well as for the identification of possible complications. As the number of cases increases, it is fundamental that radiologists understand the surgical procedure and the postoperative anatomy, as well as to recognize the possible postoperative complications and their imaging aspects, with the aim of providing the best guidance in the postoperative management of transplant recipients.

Keywords: Pancreas transplantation; Kidney transplantation; Organ transplantation; Diabetes mellitus; Postoperative complications.