I123 Ioflupane is a radiopharmaceutical for the diagnosis of Parkinson disease and its differential diagnoses.
iodine-123 is a cyclotron product
physical half-life is 13.22 hours
predominant energy of its gamma spectrum is 159 keV
Ioflupane is the international nonproprietar...
I-131 (or 131I) is a radioisotope used in the diagnosis and treatment of thyroid lesions. It is one of the oldest radiotracers used in nuclear medicine, in use for over 50 years. It is predominately used in thyroid ablation therapy, for patients post thyroidectomy, and for metastatic thyroid ca...
The ice pick sign is a smooth tapered narrowing of the upstream pancreatic duct distal to the pancreatic lesion seen frequently in benign pancreatic lesions such as a focal autoimmune pancreatitis, this is due to the extrinsic narrowing of the duct secondary to periductal fibrosis and inflammati...
The ice cream cone sign may refer to:
the appearance of the malleus head and the incus body on axial CT scan: failure of this normal configuration suggests incudomalleolar dysarticulation. Ball of the ice cream is formed by the head of malleus and cone is formed by the body of the incus. Space ...
CT scoring systems have been proposed in patients with acute respiratory distress syndrome (ARDS) to predict clinical outcomes. This scoring system was established by Ichikado et al in 2006 2 and at the time of writing (July 2016), this is the most widely used CT scoring system.
Idiopathic dilatation of the pulmonary trunk is a rare congenital anomaly comprising of pulmonary trunk enlargement with or without dilatation of the right and left pulmonary arteries.
For this diagnosis, exclusion of pulmonary and cardiac diseases (mainly pulmonary valve stenosis) and confirma...
Idiopathic dilated cardiomyopathy is a subtype of dilated cardiomyopathy. It is a type of non ischaemic cardiomyopathy where no underlying cause can be found.
This form of cardiomyopathy may account for up to 50% of all dilated cardiomyopathies 4. Patients usually ranging around 2...
Idiopathic eosinophilic oesophagitis is a cause of dysphagia, most commonly seen in males aged 20-40. On a barium swallow, there is a distinctive stricture seen with ring-like indentations.
Idiopathic giant bullous emphysema (or vanishing lung syndrome (VLS)) is characterised by giant emphysematous bullae, which commonly develop in the upper lobes and occupy at least one-third of a hemithorax. It is a progressive condition that is also associated with several forms of emphysema.
Idiopathic hypereosinophilic syndrome (IHES) is a leukoproliferative disorder and refers to a situation when there is an unexplained prolonged eosinophilia with associated organ system dysfunction. The condition can affect several organ systems which includes:
heart: cardiac involvement in idio...
Idiopathic interstitial pneumonias (IIPs) are diffuse interstitial lung diseases of unknown cause. A useful mnemonic for the American Thoracic Society-European Respiratory Society (ATS/ERS) classification of IIPs is:
All Idiopathic Chronic Lung Disease aRe Nonspecifically Patterned
Idiopathic interstitial pneumonias (IIPs) are diffuse interstitial lung diseases of unknown cause. They are characterized by cellular infiltration of the interstitial compartment of the lung with varying degrees of inflammation and fibrosis.
For many years many attempts have bee...
The approach to HRCT chest in patients with suspected idiopathic interstitial pneumonia (IIP) is with the aim to:
make sure an appropriate study requested i.e. HRCT chest with optimal individually adjusted protocol and ensure adequacy of the HRCT chest quality (see imaging protocol below)
Idiopathic intracranial hypertension (IIH), also historically known as pseudotumour cerebri, is a syndrome with signs and symptoms of increased intracranial pressure but where a causative mass or hydrocephalus is not identified.
The older term benign intracranial hypertension is ge...
Idiopathic pauci immune pulmonary capillaritis (IPIPC) is considered a rare type of pulmonary vasculitis. Some authors consider this due be an organ specific subset of microscopic polyangiitis 3. It can result in diffuse alveolar haemorrhage.
It is an isolated small vessel vasculitis...
Idiopathic pneumonia syndrome (IPS) refers to diffuse lung injury which can occur following haematopeotic stem cell transplantation where neither an infectious nor non-infectious aetiology can be found.
The incidence of IPS is thought to be around 12% following haematopoetic stem ...
Idiopathic portal hypertension (noncirrhotic portal hypertension or Banti syndrome) is a term that has been given to portal hypertension occurring without hepatic cirrhosis, parasitic infection, or portal venous thrombosis.
Rare condition. More common in India and Japan.
Idiopathic pulmonary arterial hypertension is uncommon, representing only a tiny fraction of all cases of pulmonary arterial hypertension, which has a very long list of secondary causes (see causes of pulmonary arterial hypertension).
Older terms for this entity include primary pul...
Idiopathic pulmonary fibrosis (IPF) is a clinical syndrome and considered the most common and the most lethal form of pulmonary fibrosis corresponding to the histologic and imaging pattern of UIP. It is more common in middle age or elderly men and diagnosed by:
histological or imaging pattern ...
Idiopathic pulmonary haemosiderosis (IPH) is an uncommon form of pulmonary haemosiderosis. It is characterised by the triad of
iron deficiency anemia
diffuse pulmonary infiltrates, usually represented by diffuse pulmonary haemorrhage
The diagnosis is usually made by exclusion 1.
Idiopathic pulmonary ossification (also known as bony metaplasia of lung) is a rare disorder with unknown cause characterised by bony tissue within the lung. The condition is asymptomatic.
May show branching calcific shadows are usually seen in lower par...
Idiopathic retroperitoneal fibrosis (IRF) is a sub type of retroperitoneal fibrosis where no obvious cause is found. It includes a spectrum of diseases which are characterized by fibro-inflammatory tissue surrounding the abdominal aorta and the iliac arteries. This process may extend into the re...
Idiopathic scrotal calcinosis (ISC), sometimes called dystrophic scrotal calcinosis, is a rare benign condition characterized by superficial calcifications within the skin of the scrotum of unclear etiology, typically affecting men aged 20-40. The condition is primarily cosmetic, but may recur ...
Idiopathic transient osteoporosis of the hip (ITOH) is a self limiting clinical entity of unknown cause, although almost certainly a vascular basis and possible overactivity of the sympathetic system exists. There is some controversy as to whether ITOH represents a very early, reversible stage o...
IgG-4 related lung disease is a recently described condition. It may occur with or without systemic involvement. It is considered part of the spectrum of IgG-4 related sclerosing disease.
On HRCT of the chest, it may be categorised into four major subtypes 5:
IgG4 related sclerosing disease is a systemic disease that is characterised by extensive IgG4-positive plasma cells and T-lymphocyte infiltration of various organs.
Clinical manifestations are apparent in the pancreas, biliary tree, gallbladder, salivary gland, retroperit...
Ileal atresia is a congenital abnormality where there is significant stenosis or complete absence of a portion of the ileum. There is an increased incidence in those with chromosomal abnormalities.
This article will focus on ileal atresia alone but bear in mind that some cases correspond to jej...
An ileal conduit (or "Bricker conduit") was one of the original types of urinary diversions, and it is still in use today.
The conduit is most often placed after cystectomy (or cystoprostatectomy) for muscle-invasive bladder cancer. Although not a continent diversion, it may be preferred if the...
Ileal ureter interpositions are uncommon urologic reconstructions, using a loop of small bowel to replace a damaged ureter. The concept is similar to the formation of a neobladder from small bowel (e.g. ileal conduit), except one is forming a neo-ureter.
Variants include using colon as an inter...
The ileocaecal valve separates the terminal ileum from the caecum and functions to regulate flow between these two structures and prevent reflux from the caecum into the small intestine.
The ileocaecal valve consists of two muscular layers of ileum, an upper and lower lip, that ...
The ileocolic artery is a branch of the superior mesenteric artery (SMA) that runs obliquely to the ileocaecal junction.
It divides into an ileal branch that supplies the terminal ileum and anastomoses with the terminal SMA and a colic branch that supplies the proximal ascending colon and anast...
Ileovesicostomy (also known as "cutaneous ileocystostomy", "ileal chimney", or "bladder chimney") is an uncommon urologic diversion in which a loop of small bowel is anastomosed/augmented to the dome of the bladder. This loop of bowel then exits through a urostomy. The diversion is not continent...
The ileum is the final part of the small intestine, following the duodenum and jejunum.
The ileum is not to be confused with the ilium.
The ileum is 2-4 m in length and is separated from the caecum by the ileocaecal valve (ICV). While there is no discrete line demar...
Iliac arterial aneurysms are focal dilatations of the iliac artery.
Although the dimensions that define the aneurysm are dependent on the sex of the patient and the portion of the artery involved, a common iliac artery (CIA) with a diameter ≥1.7 cm in males or ≥1.5 cm in females is considered ...
The iliacus muscle is one of the muscles of the posterior abdominal wall and contributes to the iliopsoas muscle and tendon.
origin: superior 2/3s of the iliac fossa, anterior sacroiliac ligaments and anterior sacral ala
insertion: into the psoas major tendon to form iliopsoas tendon ...
The iliofemoral ligament is very strong and shaped like an inverted Y, lying anteriorly and intimately blended with the capsule. Its apex is attached between the anterior inferior iliac spine and acetabulum rim, its base to the intertrochanteric line. The oblique lateral ligament attaches to a t...
The Iliofemoral line is traced on an AP pelvis projection. It is a curvilinear line, along the outer surface of the ilium, through the superior acetabular rim and the femoral neck.
It should be bilaterally symmetrical. Asymmetry may be the result of congenital dysplasia, slipped femoral capital...
The iliohypogastric nerve arises from the anterior ramus of the L1 nerve root of the lumbar plexus along with the ilioinguinal nerve. It a sensory nerve that provides lateral and anterior cutaneous branches supplying the posterolateral gluteal skin and skin in the pubic region.
The ilioinguinal nerve arises from the anterior ramus of the L1 nerve root from the lumbar plexus along with the iliohypogastric nerve. The predominantly sensory nerve eventually passes through the superficial inguinal ring to provide cutaneous sensation to the upper medial thigh, mons pubis and...
The iliolumbar artery is one of three branches of the posterior division of the internal iliac artery.
origin: posterior division of the internal iliac artery
supply: ilium, iliacus muscle, psoas major muscle, quadratus lumborum muscle, erector spinae muscle, anteri...
The iliolumbar ligament is a strong band of connective tissue which courses from the transverse process of L5 (in over 96% of cases) to the posterior iliac wing and iliac crest. It functions to maintain the alignment of L5 on the sacrum during various movements 1, 2.
It is an important landmark...
The iliopsoas compartment is an extra-retroperitoneal space that runs along the posterior aspect of the abdomen and pelvis and extends into the thigh.
The iliopsoas compartment is bound by the iliopsoas fascia, which is continuous with:
anteriorly: transversalis fasc...
The iliopsoas muscle is found within the iliopsoas compartment and is an important muscle in locomotion and upright posture.
origin: fusion of psoas major and iliacus muscles
insertion: lesser trochanter of the femur
nerve supply: femoral nerve; lumbar plexus
blood supply: iliolumb...
The iliotibial band (ITB) is a thick band of fascia formed proximally at the hip by the fascia of the gluteus maximus, gluteus medius and tensor fasciae latae muscles.
The band consists of deep and superficial layers:
the superficial layer is the main tendinous component and inserts onto Gerd...
Iliotibial band syndrome (ITBS), or iliotibial band friction syndrome, is a common cause of lateral knee pain related to intense physical activity resulting in chronic inflammation.
Commonly affect young patients who are physically active, most often long distance runners or cycli...
The ilium is among the three bones of the innominate bone: ilium, ischium, and pubis. These are individual bones in the youth and unite to form one bone in adults, the principal union being in the acetabulum.
Ilium is called so as it supports the 'flank'.
The ilium is not to be confused with t...
The medical terms ileum and ilium have been causing great confusion to medical students and junior doctors alike for decades now. Only separated by one letter, the second vowel, the pronunciation may be identical, or differ slightly with the i sound resembling that in "bit" for ilium (ɪlɪəm) or ...
Image guided percutaneous renal biopsy, utilising either ultrasound or CT allows for an accurate, reliable method of acquiring renal tissue for histopathological assessment.
Biopsy may be of a native or transplant kidney. It is divided into two types:
non-focal or non-targeted
focal or target...
Image interpretation questions are one of the three types of multiple choice questions on Radiopaedia, the other two being basic factual and knowledge integration.
Image interpretation questions are built entirely around an image. They should only be answerable through correct image interpreta...
Image plate artifact is caused by backscatter radiation.
Backscatter radiation is transmitted through the back of the cassette to the cassette hinge where the lead coating gets weakened or cracked.
To reduce backscatter, the radiographer should collimate where possible.
Images are clearly a very important part of Radiopaedia.org and we aim for high quality and uniformity across the site. As always patient anonymity is essential, and any images with patient details included will be removed.
JPG: small size but degraded by compression. Use qua...
Each case can have multiple studies, and each study can have multiple series. Each series is either a single image or a stack of images.
Both the study and in the individual series within it can have descriptions.
In general the 'series description' (immediately below the large image in case ...
All images should be uploaded via the "Add case" page.
NB: Although individual images/diagrams can an be uploaded directly from the image management console (via add image in article edit mode), this method is now no longer recommended and will soon be removed.
Imaging in liver transplantation is aimed to evaluate donor and recipient for successful transplantation and its outcome.
volume of liver
parenchymal disease (diffuse or focal)
Gunshot injuries often require imaging assessment, and this evaluation has both clinical relevance (assessment of organ damage, surgical planning and prognostication), and often also forensic implications.
Some understanding of the factors that influence wounding capacity ...
Imaging the shoulder is often reliant on multi-modality imaging. The shoulder is a complex ball-and-socket joint that relies on the structural integrity of the glenoid labrum and accompanying shoulder ligaments and rotator cuff muscles to function.
Acute trauma may result of bony, labral, ligam...
Immature ovarian teratomas are uncommon ovarian germ cell tumours. They differ from mature ovarian teratomas (dermoid cysts) both histologically by the presence of immature tissue, and clinically by their more malignant behaviour.
They are considerably less common than mature ovar...
Immune reconstitution inflammatory syndrome (IRIS) is paradoxical deterioration of an AIDS related illness following initiation of highly active anti-retroviral therapy (HAART) or post treatment of autoimmune disease such as multiple sclerosis.
It has been reported to affect 10-25...
The human body regularly encounters harmful microorganisms, and because of this it has developed a system of defences to help identify and eliminate infective pathogens in the body, known as the Immune system.
Humans have two types of immunity: innate immunity and acquired immunity.
Imperforate hymen is a congenital condition in which the hymen is without a normal central opening.
0.1% of patients, usually isolated findings
Primary amenorrhea with cyclic lower abdominal pain during menarche age. Imperforate hymen can be diagnosed at physic...
In utero herpes simplex infection usually occurs from transplacental tramission of the herpes simplex virus. Transplacental intrauterine infection with herpes simplex virus is an
extremely rare complication of primary herpes simplex in pregnancy.
Fetal HSV infection much less c...
In utero infections, also known as congenital infections, can result from a vast number of aetiological organisms and account for 2% to 3% of all congenital anomalies 4.
in utero toxoplasmosis infection / congenital toxoplasmosis infection:
congenital cerebral toxoplasmosis
In utero syphilis infection results from transmission of the maternal infection from the spirochete Treponema pallidum.
The pathogen is capable of crossing the placenta during any time in gestation.
The following tests can be assessed on maternal blood
An in utero varicella zoster virus infection is an infrequent type of in utero infection. The clinical features can be diverse and variable depending on the stage of gestation.
Fetal infection with varicella is unusual in the current age due to most women of childbearing age being...
In-phase (IP) and out-of-phase (OOF) sequences correspond to paired MRI gradient echo (GRE) sequences obtained with the same repetition time (TR) but with two different echo time (TE) values.
The main application of the IP-OOP sequences is to identify a pathological fat content o...
In-utero bowel perforation results in a chemical peritonitis (meconium peritonitis) from peritoneal leakage of sterile meconium.
It can result from many causes which include:
in utero intestinal ischaemia
Inanimate object inspired signs are numerous:
champagne glass pelvis: achondroplasia
dinner fork deformity: poorly set Colles' fracture
fishhook ureters: seen in BPH
apple core (napkin ring) sign: colorectal carcinoma or synovial osteochondromatosis of the hip joint
H-shaped / Lincoln log v...
The so called inca bone, also known as the preinterparietal bone or os Inca, is a triangular sutural bone located at the previous site of the posterior fontanelle. It is common and a normal variant. The inca bone is one of the Wormian bones.
It is so called because of the supposed high incidenc...
An incarcerated uterus or trapped uterus describes an extremely rare situation where a retroverted or retroflexed gravid uterus fails to ascend into the abdominal cavity.
This is an uncommon presentation and is said to occur in 1 in 3000 pregnancies. Uncomplicated retroversion may...
Incidental lung nodules are encountered commonly in routine cross sectional imaging. The risk of developing cancer in very small nodules (<5mm) is very low. However, clear-cut recommendations are still not in place with high variation in practice amongst reporting radiologists 1. As a result, it...
The majority of splenic lesions are benign and when an incidental splenic lesion is found in an asymptomatic patient, it may pose a dilemma in workup because imaging findings are often nonspecific.
benign imaging features: no follow up
An incidentaloma is a radiological neologism to denote a mass lesion found incidentally and of dubious clinical significance. Although it can refer to any incidental lesion (e.g. pituitary 3, thyroid 4), it is most often used to denote an incidental adrenal lesion, which is commonly an adrenal a...
Incisional hernias are relatively common and along with parastomal hernias, umbilical hernias, paraumbilical hernias and spigelian hernias, they are usually anterior abdominal hernias.
Usually develop within a few months of surgery but a small proportion can remain clinically sile...
The maxillary incisive canal runs through the maxilla in the midline. It connects the inferior nasal cavity with the superior oral cavity, opening at the incisive foramen posterior to the central maxillary incisor teeth. It contains the descending palatine artery and the nasopalatine nerve.
Incisive canal cysts, also known as nasopalatine duct cysts (NPDC), are developmental, non-neoplastic cysts arising from degeneration of nasopalatine ducts. These ducts usually regress in fetal life. The persistence of ductal epithelium leads to formation of cyst.
It is considered the most comm...
The incisive foramen (also known as nasopalatine foramen or anterior palatine foramen) is the oral opening of the nasopalatine canal. It is located in the maxilla bone in the incisive fossa, midline in the palate posterior to the central incisiors, at the junction of medial palatine and incisive...
Inclusion body myositis (IBM) is a type of inflammatory myopathy. It is often considered is the most common acquired myopathy in patients older than 50.
Inclusion body myositis tends to present in older individuals 4 (often after the age of 50), although the disease may occasional...
The incomplete border sign is useful to depict an extrapulmonary mass on chest radiograph.
An extrapulmonary mass will often have a inner well defined border and an ill-defined outer margin 1-3. This can be attributed to the inner margin being tangential to the x-ray beam and has good inherent ...
Incomplete double aortic arch is a rare vascular ring anomaly wherein a segment of the minor aortic arch, usually the left, is atretic.
As in the case of other vascular rings, this anomaly can cause 1:
Some patients may reach adulthood with...
Incomplete fractures are a heterogeneous group of fractures that predominantly occur in the long bones of paediatric patients. Rang 1 describes a continuum of fractures that occur with increasing longitudinal force applied along the length of the bone. At the point where force exceeds the struct...
Incomplete hippocampal inversion unsurprisingly describes the situation where the normal inversion of the hippocampus fails to happen during development.
Incomplete hippocampal inversion is the most correct description of this finding. Hippocampal malrotation is a term used by some...
Incomplete miscarriage is a term given to miscarriage where there are retained products of conception still within the uterus.
Ultrasound appearance is variable, ranging from visible fetal parts to a mass of mixed echogenicity. The presence of a prominent vasc...
Incontinentia pigmenti, also known as Bloch-Sulzberger syndrome, is a rare condition that can affect many body systems, specially the skin. As a X-linked genetic disorder, it occurs much more often in females than in males.
Incontinentia pigmenti is rare and the true prevalence is...
A generalised acceleration in bone maturation can result from a number of aetiological factors. They include :
idiopathic isosexual precocious puberty
hypothalamic or parathalamic lesion with sexual precocity: e.g.
A handy mnemonic for causes of generalised increased bone density:
Regular Sex Makes Occasional Perversions Much More Fun, Happening and Lovely
R: renal osteodystrophy
S: sickle cell disease
M: metastasis (osteoblastic)
P: pyknodysostosis; Paget's disease
Increased cardiothoracic ratio describes widening of the cardiac silhouette on a chest radiograph. This is only of use when making assessment of a PA chest x-ray since the AP chest x-ray causes artefactual magnification of the heart and the cardiothoracic ratio is altered.
A mnemonic that can be used to remember the causes of increased heel pad thickness is:
D: phenytoin therapy
P: peripheral oedema
Increased renal echotexture is a non specific finding but can represent a number of pathologies.
echogenic renal pyramids - paediatric
Article being written
Increased retrosternal airspace is an indicator of hyperinflation of the lungs and is usually due to emphysema.
The thickness of the space between the ascending aorta and the posterior margin of the sternum (3 cm inferior to the sternomanubrial joint) and is normally no more than 2.5 cm 1 altho...
Increased splenic density can be due to a number of processes. The density may be due to calcification (most common) or other compounds (iron, Thorotrast), and can be seen (often incidentally) on abdominal radiographs and CT. On CT the usual splenic attenuation is 35-55 HU or ~10 HU 6 lower tha...
The incus is the middle of the ossicles articulating with the head of the malleus anteromedially and the stapes inferomedially.
Its parts include:
a body which articulates with the head of the malleus, and to which the superior ligament of the incus is attached (to the roof of the middle ear c...
The so-called india ink artifact also known as the black boundary artifact is an MRI feature seen on out-of-phase imaging and represents signal drop out in voxels that contain both fat and non-fat components. As such it is seen surrounding interfaces, lending the image an appearance as if someon...
Neuroimaging in new onset seizures is recommended for all patients, even with return to baseline neurological status. This is specifically recommoneded in the context of
new focal deficits
persistent altered mental status