Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

23 results found
Article

Timed barium esophagogram

The timed barium esophagogram (TBO) is a simple physiologic assessment and objective method for assessing the esophageal emptying used in patients with suspected achalasia and to evaluate and follow up patients who have been treated with myotomy or pneumatic dilatation1,3. Technique Several te...
Article

CT chest abdomen-pelvis (protocol)

The CT chest-abdomen-pelvis protocol serves as an outline for an examination of the trunk covering the chest,  abdomen and pelvis. It is one of the most common CT examinations conducted in routine and emergencies. It can be combined with a CT angiogram. Note: This article aims to frame a genera...
Article

CT abdomen-pelvis (protocol)

The CT abdomen-pelvis protocol serves as an outline for an examination of the whole abdomen including the pelvis. It is one of the most common CT protocols for any clinical questions related to the abdomen and/or in routine and emergencies. It forms also an integral part of trauma and oncologic ...
Article

CT pancreas (protocol)

The CT pancreas protocol serves as an outline for a dedicated examination of the pancreas. As a separate examination, it is usually conducted as a biphasic contrast study and might be conducted as a part of other scans such as  CT abdomen-pelvis, CT chest-abdomen-pelvis. Note: This article aims...
Article

Chronic appendicitis

Chronic appendicitis (rare plural: appendicitides) is defined by inflammation of the appendix over time with symptoms lasting for more than three weeks duration (cf. acute appendicitis) 1. The condition should be differentiated from recurrent appendicitis, in which one or more episodes of flares...
Article

Fluoroscopy

Fluoroscopy is an imaging modality that allows real-time x-ray viewing of a patient with high temporal resolution. It is based on an x-ray image intensifier coupled to a still/video camera. In recent years flat panel detectors (which are similar to the digital radiography used in projection radi...
Article

Ultrasound elastography

Ultrasound elastography, also called as sono-elastography, is a modern evolutionary method of sonographic imaging. Techniques include shear wave elastography (also known as transient elastography) and strain elastography (also known as static or compression elastography). These techniques utiliz...
Article

Portosystemic shunt ratio

The portosystemic shunt ratio is a measure performed using ultrasound to quantify the abnormal flow of portal venous blood that is shunted away from the hepatic sinusoidal circulation in the context of a congenital portosystemic shunt 1. Measurement The ratio is determined on ultrasound using ...
Article

Enteric contrast medium (CT)

Enteric contrast media can be given to patients before their CT exam to improve its diagnostic accuracy. Historically, a combination of oral and intravenous contrast media were always given prior to a CT abdomen. Contemporaneously, improved CT scanners mean that oral contrast agents are no longe...
Article

Indium-111 OncoScint

Indium-111 OncoScint is a radiopharmaceutical used in SPECT imaging. It is a labeled monoclonal antibody that is directed against TAG-72, which is a tumor-associated antigen associated with ~95% of colorectal carcinomas and 100% of ovarian carcinomas 1,2. Background hepatic uptake limits sensiti...
Article

SeHCAT

SeHCAT™ (23-seleno-25-homo-tauro-cholic acid or tauroselcholic acid) is a radiopharmaceutical used in the investigation of bile salt malabsorption, which is a cause of chronic diarrhea.  Characteristics physical half-life: 118 days Uses, dosage and timings A capsule containing SeHCAT is inge...
Article

MR enterography

MR enterography (MRE) is a non-invasive technique for the diagnosis of small bowel disorders. Note: This article is intended to outline some general principles of protocol design. The specifics will vary depending on MRI hardware and software, radiologist's and referrer's preference, institutio...
Article

CT colonography (protocol)

Computed tomographic (CT) colonography, also called CTC, virtual colonoscopy (VC) or CT pneumocolon, is a powerful minimally invasive technique for colorectal cancer screening.  Indications screening test for colorectal carcinoma colon evaluation after incomplete or unsuccessful optical (conv...
Article

Twinkling artifact

Twinkling artifact is seen with color flow Doppler ultrasound 1. It occurs as a focus of alternating colors on Doppler signal behind a reflective object (such as a calculus), which gives the appearance of turbulent blood flow 2. It appears with or without an associated color comet tail artifact ...
Article

Gastrointestinal MRI contrast agents

Gastrointestinal MRI contrast agents may be helpful in certain clinical scenarios in distinguishing bowel from intra-abdominal masses and normal organs. The contrast agents can be divided into positive agents (appearing bright on MRI) or negative agents (appearing dark on MRI). Positive contras...
Article

CT enteroclysis (protocol)

Computed tomographic (CT) enteroclysis refers to a hybrid technique that combines the methods of fluoroscopic intubation-infusion small bowel examinations with that of abdominal CT. Indications CT enteroclysis is complementary to capsule endoscopy in the elective investigation of small-bowel d...
Article

Scintigraphy performed with Tc-99m labeled RBCs

Tc-99m labeled RBCs - with radiolabelling technique in vivo or in vitro of red cells 3 - is one of the technetium radiopharmaceuticals used in the non-invasive assessment of gastrointestinal (GI) bleeding 2, characterized by high sensitivity (93%) and specificity (95%) 4. It is capable, in fact,...
Article

Tc-99m pertechnetate

Tc-99m pertechnetate (Na+ 99mTc O4-) is one of the technetium radiopharmaceuticals used in imaging of thyroid, colon, bladder and stomach. Technetium (99mTc) has eight oxidation states 6, from -1 to +7; specifically, the oxidation state of technetium in the pertechnetate anion (99mTcO4-) is +7....
Article

Vicarious contrast media excretion

Vicarious contrast media excretion (VCME) refers to the excretion of intravascularly-administered water-soluble iodinated contrast media in a way other than via normal renal excretion. Epidemiology The most common vicarious excretion of water-soluble contrast material is via the liver, resulti...
Article

Tc-99m sulfur colloid

Technetium-99m sulfur colloid is one of the technetium radiopharmaceuticals. Characteristics photon energy: 140 keV physical half-life: 6 hours biological half-life: 2 to 3 minutes normal distribution: liver: 85% spleen: 10% bone marrow: 5% excretion: hepatic target organ: liver, splee...
Article

Octreotide scintigraphy

Octreotide scintigraphy uses 111In-labeled octreotide, which is a somatostatin analog; it is also known as Octreoscan, a brand name for 111In-labeled pentetreotide. Pentetreotide is a DTPA-conjugated form of octreotide, originally manufactured by Mallinckrodt Nuclear Medicine LLC, which now form...
Article

Rectal cancer protocol (MRI)

MRI protocol for rectal cancer is a group of MRI sequences put together for imaging staging of primary tumors of the rectum and assessment of response following neoadjuvant therapy. Modified versions of the protocol may also be used for the assessment of local recurrence. Note: This article is ...
Article

Chemical shift artifact

Chemical shift artifact or misregistration is a type of MRI artifact. It is a common finding on some MRI sequences and used in MRS. This artifact occurs in the frequency-encoding direction and is due to spatial misregistration of fat and water molecules.  Chemical shift is due to the difference...

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