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MRI for vascular imaging

MRI for vascular imaging

look at imagging abnormalities MRI for vascular imaging blood vessels, especially MRI for vascular imaging in flr e. J Magn Reson Imaging 24 4 — Article PubMed Google Scholar Bernstein EJ, Schmidt-Lauber C, Kay J Nephrogenic systemic fibrosis: a systemic fibrosing disease resulting from gadolinium exposure. Eur J Radiol 67 1 —

MRI for vascular imaging -

CT perfusion studies enable differentiation of salvageable ischemic brain tissue penumbra from irreversibly damaged brain infarct core. Therefore, this becomes useful when assessing a patient for potential treatment e.

thrombolysis or clot retrieval. Other potential uses of CT perfusion imaging that has been identified has been in evaluating and following chronic cranial and extracranial atherosclerotic-occlusive disease, assessing vessel spasm after subarachnoid hemorrhage, distinguishing brain cancer from infections, and in confirming brain death.

CT perfusion is based upon a tracer kinetic model e. CT perfusion, MR perfusion and assumes a nondiffusible tracer. This first-pass technique monitors changes in density as a function of time. Pixel-based time attenuation curves are then produced by deconvolution.

From this data, quantitative cerebral perfusion maps, including cerebral blood flow, cerebral blood volume, and mean transit time, are constructed.

In other words, the CT scan takes X-ray pictures over time as the body takes up more and more of a nonradioactive substance that the cells of the body take in. CT perfusion can be performed quickly, safely, and in the same scanner used for a noncontrast brain CT.

Therefore, CT perfusion studies do expose the patient to a small amount of radiation. A noninvasive technique that uses magnetic field and computer-generated radio waves to create detailed images and is the most frequently used imaging test of the brain and spinal cord.

Unlike X-rays or computed tomography CT scans , MRI does not use ionizing radiation. MRI may be preferable to CT scans in situations where organs or soft tissue is being studied, as it is better at telling the difference between normal and abnormal tissue.

MRIs may be used to examine the brain for injuries or the presence of structural abnormalities or other conditions including tumors, abscesses, congenital abnormalities, aneurysms, venous malformations, hemorrhage, and hydrocephalus. An MRI machine is a large, cylindrical tube-shaped machine that creates a strong magnetic field around the patient.

This field, along with radio waves, alters hydrogen atoms natural alignment in the body and the pulses from these radio waves produced by the scanner knock the nuclei of your atoms out of normal position. As the nuclei realign back into their proper position, they send out radio signals which are received by a computer to analyze and convert them into a two-dimensional 2D image of the brain.

Although the test is non-invasive, some patients may experience claustrophobia in the imager. The powerful magnetic field can affect implanted metal and therefore patients with gunshots or surgical implants like artificial joints, pacemakers, or stimulators may not be able to have an MRI.

Some programmable VP Shunts are MRI safe but need to be reprogrammed after each scan. All modern endovascular devices are MRI compatible but certain older surgical clips might not be. Often technologists will ask for a make and model of any devices so it is helpful to have this information before you go for a scan.

MRI is very sensitive for the swelling that goes along with a cerebral infarction or ischemic stroke and can identify strokes earlier than CT and strokes that are too small for a CT.

Unlike catheter angiography, which requires inserting a catheter into an artery, MRA is noninvasive and less painful. Unlike a CTA, no ionizing radiation is used.

Furthermore, an MRA does not necessarily require contrast and if it does it is not iodine based but is gadolinium. Cerebral angiography, also known as intra-arterial digital subtraction angiography, is an invasive procedure that produces X-ray pictures of the blood vessels in the brain and neck.

Specifically, this test looks for changes in the blood vessels including blockages occlusive disease , narrowing stenosis , ballooning aneurysm , inflammation vasculitis , vessel spasm vasospasm , and vascular malformations. In this procedure, contrast dye is utilized as arteries and veins are not normally seen in an X-ray picture.

The patient is given a local anesthetic, the artery is punctured usually in the leg and a needle is inserted into the artery. A catheter a long, narrow, flexible tube is inserted through the needle and into the artery.

It is threaded through the main vessels of the abdomen and chest aorta until it is properly placed in the arteries of the neck and head. This procedure is monitored by a fluoroscope a specialized X-ray that is projected onto a TV monitor to verify the location of the catheter and to monitor the vessels of the head and neck after injecting contrast material.

Contrast dye is injected via the catheter to make blood vessels show up on the X-ray image and allows the healthcare provider to better see the structure of the vessels, at which time a series of X-rays will be taken of the arteries, capillaries, and veins.

When the test is done, the catheter is removed and pressure is applied over the artery to prevent bleeding and formation of a hematoma a collection of blood under the skin. The risks to this procedure includes radiation exposure and risk of allergic reaction to contrast dye.

As this procedure is invasive and involves the blood vessels and blood flow of the brain, there is a small risk of transient ischemic attack brief-stroke like condition , stroke, bleeding, blood clots, paralysis on one side of the body hemiplegia , loss of the ability to speak or understand speech aphasia , and hematoma at the catheter placement site.

In experienced hands, the risk if very low. This study provides the gold standard look at cerebral blood vessels with a level of detail beyond that of the other modalities.

Furthermore, since pictures are taken multiple times per second, blood flow can be evaluated. This is particularly helpful in AVMs and AVFs. The procedure usually takes about 45 minutes and often a patient has to lay flat or stay in the hospital recovery area for a few hours after.

Most facilities ask that an angiogram patient not drive themselves home. According to current knowledge, the examination itself is harmless. Metallic foreign body implants can produce artifacts or heat up, so they must be identified in advance.

The selection of the scanning planes and slice thickness depends on the body region to be examined. The examination time is mainly determined by the field of view to be covered and by the number of selected MRI sequences.

It typically ranges between 20 minutes and one hour. In view of the high soft tissue contrast and the possibility of dynamic vascular imaging MR angiography , magnetic resonance imaging MRI is today the gold standard for evaluation of vascular anomalies and is superior to computed tomography CT in many respects, not only because of the lack of use of X-rays.

The exact anatomical extension and type of vascular anomaly can be determined with a high degree of accuracy see table below: Typical MRI findings in vascular anomalies. If a vascular anomaly is suspected and an invasive procedure is discussed, a dedicated MRI should be performed at least once.

The basic sequence protocol includes non-enhanced T1-weighted fast spin-echo sequences without fat suppression and T2-weighted sequences with fat suppression STIR. In addition, T2-weighted fast spin-echo sequences without fat suppression are helpful.

After application of gadolinium MRI contrast agents, T1-weighted sequences with fat suppression e. The administration of contrast agents can also be used to perform time-resolved MR angiography MRA.

The numerous different MRI sequences sometimes add up to long examination times up to minutes depending on the body region. For some patients the MRI examination may be accompanied by feelings of anxiety or claustrophobia, and there is a high noise level earplugs may be necessary.

Patients with claustrophobia may sometimes require appropriate sedation. In infants and small children, a time-consuming MRI can only be performed under general anesthesia. A prerequisite for the application of an MRI-specific contrast medium is a satisfactory kidney function and exclusion of other contraindications.

Furthermore, before each MRI examination, it must be ensured that no ferromagnetic foreign materials are in contact with the body or have been implanted in the body.

Magnetic resonance imaging. Chapter: Imaging Article: 4 of 10 Update: Feb 05, Author s : Müller-Wille, René. Infantile hemangioma : In the proliferation phase , infantile hemangiomas appear hypointense to isointense in non-enhanced T1-weighted sequences and strongly hyperintense with sharp margins in T2-weighted sequences.

Flow voids in the incoming and outgoing vessels indicate a high blood flow. After administration of contrast medium , proliferating infantile hemangiomas enhance early, intensely and homogeneously and are sharply demarcated. However, there is no immediate arteriovenous shunting as in true arteriovenous malformations.

During the involutional phase, the increased fat deposition leads to a signal increase in T1-weighted sequences. The contrast medium uptake is reduced. The SPA is mainly fed by the UA and ensures at least the vascularisation of the last three or four fingers.

The SPA is covered by skin and the palmar fascia. Its most distal part projects between the proximal and distal palmar creases.

There are many anatomical variations of the SPA Fig. It may be barely perceptible or, conversely, equal to the diameter of the RA. Its origin is also variable. It is often associated with a bifid median nerve; in that case, it travels between the two nerve trunks [ 16 ].

The SPA classification by Coleman and Anson [ 12 ] with two groups: group I with complete arch and group II with incomplete arch. In group I, contributing vessels anastomose with each other or the UA extends to the thumb. Group I is further divided into five types: Type A, classical radio ulnar arch, formed by the superficial palmar branch of RA and the main stem of the UA; Type B, arch formed entirely by the UA; Type C, median-ulnar arch, composed of the UA and an enlarged median artery; Type D, radio-median-ulnar arch, three vessels enter into formation of the arch; and Type E, arch initiated by the UA and completed by a large-sized vessel derived from the deep arch.

In group II, contributing vessels do not anastomose with each other or the UA fails to reach the thumb. Group II is further divided into four types: A, B, C, and D, similar to group I except Type E, which has no representation in group II. Some other subtypes have also been described.

The DPA is mainly supplied by the RA and ensures vascularisation of the first two fingers. The DPA travels to the palmar surface of the bases of the metacarpal bones deep to the deep flexor tendons.

It gives rise to four palmar metacarpal branches. The first palmar metacarpal artery FPMA ensures vascularisation of the thumb and feeds the palmoradial digital artery of the index finger. The palmar metacarpal arteries of the second, third, and fourth spaces each receive a perforating branch originating from the corresponding dorsal interosseous artery before anastomosing with the corresponding common digital artery originating from the SPA.

These arteries are then divided into palmar collateral arteries. The thumb arterial system may be supplied by the DPA, the SPA, and the dorsal system Fig. The FPMA and the first dorsal metacarpal artery are the main branches that provide the thumb vasculature.

The palmar arteries of the thumb are almost always present and large, unlike the inconsistent dorsal arteries that have a small diameter. In most cases, the widest artery is the ulnopalmar digital artery [ 17 ]. The fingers are vascularised by two palmar and two dorsal arteries.

The palmar arteries are more important. The dorsal arteries of the long fingers only vascularise the dorsal aspect of the first phalanx. CTA and MRI are both efficient methods to evaluate hand vessels and lesions with a vascular origin.

However, advanced CT techniques, such as dynamic CTA and SHR-CTA, have increased the frequency with which CTA is performed Table 1. In any case, to guarantee a high-quality examination, hand imaging should be carried out independently and not as part of a complete upper limb imaging protocol.

For both CTA and MRA of the hand, it is important to avoid patients with cold hands and those who smoked tobacco or cannabis prior to the examination because these conditions can generate vasoconstriction, which is detrimental to the exploration of the digital arteries.

Hand warming or 1 min of squeezing exercises results in physiologic vasodilation, which is useful to improve visualisation of small vessels [ 8 , 18 ]. Single scan upper limb CTA can be performed with sufficient quality up to the distal portion of the RA and UA but no further.

This is because it is difficult to estimate the ideal timing to achieve satisfactory enhancement of both the proximal and distal arteries and digital artery evaluation requires optimised spatial resolution, which is not achievable with an upper limb run-off Fig.

Comparison of the image quality between a complete upper extremity run-off and a CTA of the hand in a year-old patient with HHS, presenting with ischaemia of the fourth and fifth fingers.

a A complete upper extremity run-off was first obtained showing a probable occlusion of the UA. b , c CTA of the hand showed a 6-cm-long occlusion of the UA, the patency of the deep branch of the UA curved arrow , which is fed by the DPA, the occlusion of the ulnopalmar artery of the fifth finger and the distal occlusion of the radiopalmar artery of the fourth finger arrowheads.

d GI providing an overview of the lesions and of the arterial configuration of the hand showing the deep branch of the UA curved arrow and the occlusion of the ulnopalmar artery of the fifth finger arrowhead. CTA of the hand if possible is performed in prone position with flat hand on the table with fingers extended superman position in order to place the hand as much as possible in the centre of the scanner to increase spatial resolution Figs.

Bilateral CTA shows occlusion and wall thickening of the right RA and of both UA straight arrows. Note also a tenosynovitis of the extensor carpi radialis and of the extensor digitorum of the right wrist arrowheads. Optimal injection and acquisition parameters are critical when imaging the hand [ 19 ].

Iodinated contrast medium ICM should be injected into a contralateral peripheral vein. Alternatively, injection can also be performed in an ipsilateral antecubital vein, more proximal relative to the study area.

Around 1. A test-bolus or bolus-tracking technique is mandatory. For helical CTA, a simple and efficient approach is to use bolus tracking with UA and RA visual monitoring and manual triggering.

In helical mode, two successive acquisitions are carried out after ICM injection, in the same direction from the proximal to distal location. Even with a delay after contrast injection over 10 s, the contrast bolus can be outrun during the first acquisition.

A double acquisition allows a better distinction between arteries and veins, as well as between delayed opacification and occlusion of the digital arteries. A late acquisition may also be useful for detecting arterial wall thickening and enhancement in cases of occlusion or an inflammatory arterial wall disease.

A low-dose technique with 80 or kVp increases the contrast at the enhanced vessels and reduces patient exposure [ 18 ]. SHR-CTs are novel commercial systems with 0. SHR improves the quality of both native images and multiplane reformats, especially the depiction of small vessels, particularly the distal portion of the digital arteries Fig.

Traumatic occlusion of the radial digital arteries of the fourth finger in a year-old man. a SHR-CTA at the level of the first phalanx showing the occlusion of the radiopalmar and radiodorsal digital arteries of the fourth finger arrows as well as a reduction of the venous flow. b GI showing the occlusion of the radiopalmar artery at the level of the first phalanx and of the ulnopalmar artery associated with corkscrew collaterals arrowheads.

Dynamic CTA simultaneously yields an anatomic and a functional vascular evaluation [ 10 , 11 , 18 ]. Large detector CT scanners e. CT perfusion allow multiphasic arterial exploration with up to 16 cm of Z-axis coverage without compromising spatial or temporal resolution.

Indeed, dynamic CTA warrants a short volume acquisition time 0. all voxels of a given volume are acquired almost at the same time , and a free choice of inter-volume delay. A 5-s inter-volume delay is a good trade-off between temporal resolution and radiation dose.

If bone subtraction techniques are applied, images with a pseudo-angiographic effect can be generated Fig. Dynamic CTA of the hand can be useful to evaluate vascular malformations because it allows visualisation of the lesion at the best vascular phase Fig. It also provides a functional evaluation of the arterial network of the hand in the preoperative evaluation of hypothenar hammer syndrome HHS.

The same technique applied at the shoulder girdle has also been shown to be effective in diagnosing thoracic outlet syndrome [ 21 ]. Dynamic CTA of an arteriovenous fistula straight arrow fed by the ulnopalmar digital artery curved arrow of the fourth finger in a year-old patient.

a, b Native slice and VRT image with bone subtraction at the early arterial phase showing the fistula and the early enhancement of an ulnopalmar vein arrowhead.

Dynamic CTA allows capturing the lesion at the best vascular phase. Post-processing is required to visualise and interpret SHR-CTA datasets and to communicate findings to referring physicians [ 8 , 9 , 22 , 23 ].

Post-processing includes multiplanar reconstruction MPR , maximum intensity projection MIP images, and volume rendering technique VRT , which has been replaced by global illumination rendering GI [ 24 , 25 ]. In all cases, three-dimensional 3D images must be analysed in comparison with native slices due to possible artefacts in small vessel segmentation.

This endeavour requires high spatial resolution, good vascular enhancement, and satisfactory signal-to-noise ratio to be effective. Finally, the radiation dose to the patient remains low, ranging from 0. The patient should be scanned in a comfortable position to avoid motion artefacts.

A dedicated coil is essential to obtain high-quality images regardless of the field strength of the MRI system Fig. A flexible coil is used for the hand, and a wrist coil is used for the wrist or the thumb. AVM of the hypothenar eminence in a 37 year-old-woman.

a Coronal T2-weighted MR image showing the nidus with multiple enlarged vessels with flow void arrow indicating a high-flow malformation. b MRA demonstrating the high flow of the malformation with a rapid vascular enhancement of the nidus arrow , multiple feeding arteries, and early venous drainage through dilated veins.

In most cases, MRA is not the only acquisition to be performed and the protocol also comprises conventional sequences with T1-weighted, fluid-sensitive sequences such as fat-suppressed T2-weighted MRI scans, and contrast-enhanced T1-weighted fat-suppressed sequences Table 3.

These morphologic sequences allow the characterisation of soft tissue masses and also the evaluation of the para-arterial environment e. extrinsic compression, inflammatory changes.

In addition, contrast-enhanced T1-weighted fat-suppressed sequences provide a means to evaluate thickening and enhancement on the arterial wall.

The technical aspects and specific protocols for MRA have been well described in the literature [ 3 , 4 , 26 , 27 ]. MRA is usually based on the administration of a gadolinium-based contrast agent and time-resolved approaches. Time-resolved sequences use various patterns of partial K-space filling with an oversampling of the K-space centre; the approach generates images with good temporal and spatial resolution compromise.

Images can be analysed with subtraction technique, which improves contrast resolution, or without subtraction technique, thus allowing visualisation of the background. Although not recommended for quantitative perfusion analysis, time-resolved sequences are ideal for visual analysis of the hand vasculature and provide a vascular map and haemodynamic information, including inflow in the vessels or arrival times to the tissue [ 1 , 3 , 18 ].

For the evaluation of the hand, we use a time-resolved 3D sequence with a repetition time TR of 4. In general, an injection of 0. The use of an injection pump is necessary, and the delay between acquisition start and contrast injection is dependent on the length of the mask acquisition, which usually lasts around 40 s variations depending on coverage and slice thickness.

For optimal evaluation of the hand, contrast injection starts 30 s after the beginning of the mask sequence. The diagnosis of vascular lesions of the hand is often based on clinical history and clinical examination. Most of the pathologies require US examination which in many cases is sufficient to reach the diagnosis.

However, CTA and MRA which provide distinct advantages over ultrasound may be indicated, and we will focus on their findings in the different entities.

It should also be noted that incidental discovery of a vascular lesion on MRI is not uncommon and radiologists must be aware of this situation.

This chapter is divided into two parts. The first part covers vessel injuries and ischaemia causing lesions. The second one describes the vascular malformations and the vascular and perivascular tumours affecting the hand.

The causes of hand ischaemia are varied Table 4. The three main causes of digital ischaemia, which alone represent almost two-thirds of patients with hand ischaemia, are autoimmune disorders foremost among which is systemic sclerosis [SSc] , occupational causes, and Buerger's disease.

It is likely that traumatic or microtraumatic arterial injury in the hand is widely underdiagnosed because: 1 the causative trauma is often unrecognised; 2 symptoms may be delayed, minor, or non-specific; 3 the clinical presentation may mimic other causes of digital ischaemia; and 4 imaging findings may be subtle or confusing.

Therefore, imaging of the arteries of the entire upper limb is necessary in the event of suspected embolism due to lesions of the large vessels.

Radiologists should specifically search for aneurysms of the axillary artery or posterior circumflex artery in sports with overhead arm motion such as volleyball and tennis Fig. Distal emboli due to an aneurysm of the axillary artery in a year-old female professional volleyball player.

a Axial contrast-enhanced T1-weighted fat-suppressed sequence showing some emboli in the UA and RA arrows. b CTA of the entire upper limb showing an aneurysm of the axillary artery.

Radial and ulnar arterial access is frequently used for catheterisation, and transradial access is increasingly used for coronary angiography and percutaneous coronary intervention [ 30 ].

Iatrogenic conditions are mainly represented by occlusion of the RA. It must be prevented by appropriate anticoagulation and should be detected by US before the patient is discharged. It is generally silent, but it affects the vascular reserve of patients who may have to undergo further vascular exploration [ 31 , 32 ].

Post-catheterisation aneurysm is exceptional and generally occurs in an infectious context. Iatrogenic vascular-surgery-related hand complications also include RA harvest for coronary artery bypass, haemodialysis access, or axillo-femoral bypass graft [ 33 , 34 ].

Finally, pseudoaneurysm of the SPA may exceptionally occur after carpal tunnel decompression. Of these, brachial artery lacerations are the most common, followed by those of the RA and UA, while digital artery lacerations are the least frequent.

Digital artery lacerations usually occur secondary to open puncture wounds to the hand, but these injuries may also result from severely displaced fractures, crush injuries, gunshots, and other penetrating wounds.

Acute artery lacerations of the hand do not require a CTA, except in cases of associated complex bone lesions or multiple vascular lesions. CTA findings include active extravasation, luminal narrowing, lack of luminal contrast opacification, filling defect, arteriovenous fistula, and pseudoaneurysm Figs.

Surprisingly, pseudoaneurysms of the hand are exceptional despite the high frequency of hand trauma Fig. They can affect the RA or UA, the palmar arches, and the digital arteries, presenting clinically as a small mass, sometimes occurring several months after the trauma without any pulsatility.

When surgery is required, CTA or MRA provides a global assessment of the vascular network required for treatment planning [ 37 , 38 ].

Occluded pseudoaneurysm of the radiopalmar artery of the index finger in a year-old woman with repetitive microtrauma. a Photograph showing a blue mass under the skin at the level of the metacarpophalangeal joint arrow. b Axial T2-weighted MR image showing the pseudoaneurysm arrow with an intraluminal thrombus.

Occlusion of the digital arteries that results from acute blunt trauma is exceptional [ 18 ]. Those described in baseball catchers affect the index finger and are associated with hypertrophy of this finger [ 39 ].

Finger artery occlusion has also been described after prolonged strangulation of the fingers due to the wearing of a plastic bag.

It is referred to as hammer syndrome because in most cases it originates from repetitive strikes and microtrauma to the ulnar side of the palm of the hand [ 14 , 40 ]. However, HHS may also be due to a unique trauma on the palm of the hand.

The clinical manifestations depend on the location and extension of the lesions as well as the configuration of the vascular network.

Some clinical symptoms may be misleading because a UA aneurysm can be responsible for a mass effect or cause compression of the ulnar nerve or of its superficial sensitive branch Fig. HHS in a year-old manual worker exposed to different causative factors, including vibrating tools.

a , b Axial and coronal T2-weighted MR images showing an occluded aneurysm arrow of the distal portion of the distal UA and severe osteoarthritis affecting the trapeziometacarpal joint.

c , d Axial image and GI with dynamic CTA showing the distal occlusion of the UA, the patency of the SPA fed by the FPMA, a corkscrew deformity of common digital arteries, and the UA at the level of the ulnar head curved arrow.

Note the close relationship between the aneurysm and the superficial branch of the ulnar nerve arrowhead. HHS is common in middle-aged, active, smoking men; it generally affects the dominant hand. HHS can be related to sports racket sports, mountain biking, and breakdancing or professional activities in which the hand is used to hit, push, or squeeze hard objects.

They are mainly performed if surgical treatment is discussed to show the extent of vascular occlusion and its functional impact [ 43 ]. It should be noted that the late phase with CTA and contrast-enhanced T1-weighted fat-suppressed sequence show a thickening and an enhancement of the arterial wall that underline the thrombus.

For these reasons, the diagnosis may be overlooked if only conventional sequences are performed because the thrombus may be misinterpreted as a flow phenomenon Fig. UA changes initially result in parietal thickening that gradually progresses to occlusion. Occlusion then extends proximally in a variable manner towards the level of the first carpal row or even the distal ulna.

Distal compromise of the SPA is also frequent. Intimal lesions may result in clot formation and emboli to the digital arteries usually of the fourth and fifth fingers. Aneurysms are less common.

Arterial dysplasia is frequently associated; it is characterised by a tortuous, helical corkscrew deformity of the UA, SPA, and sometimes common digital arteries [ 14 , 18 , 40 ].

This deformity is probably associated with arterial wall fragility and may increase the risk of arterial trauma because of greater exposure of the affected segment of the UA to the hamulus. A pitfall in a case of HHS in a year-old manual worker with an occlusion of the UA.

a—c Axial T1-weighted a and T2-weighted b MR images and contrast-enhanced T1-weighted fat-suppressed sequence c showing a subtle thickening and parietal enhancement of the UA arrow.

The thrombus should not be confused with a flow phenomenon. Surgical treatment is indicated when there is an aneurysm, ischaemic phenomena, or severe functional impairment resistant to medical treatment.

It consists of removing the affected segment and reestablishing flow with venous or arterial bypass. Smoking cessation is obviously recommended, and occupational reclassification may be indicated [ 43 , 44 , 45 ]. A so-called thenar hammer syndrome has been described and is exceptional.

Repeated microtrauma to the palmar surface of the wrist is likely to generate lesions of the RA that are identical to those described for the UA in HHS.

Playing volleyball has been reported to cause this condition. HAVS is a prevalent occupational disease that affects workers in multiple industries in which vibrating tools are used.

HAVS mainly affects men over 35 years of age. It has three components: vascular, sensorineural, and musculoskeletal. Symptoms vary by intensity and duration of vibration exposure [ 45 , 46 ].

Neurosensory signs appear first paresthesia, loss of sensitivity, and carpal tunnel syndrome. Imaging techniques may show the vascular lesions found in HHS because HHS and HAVS share some aetiological factors. HAVS in a year-old man. a Coronal T2-weighted MR image showing isolated osteoarthritis of the radioscaphoid compartment of the radiocarpal joint.

b Contrast-enhanced T1-weighted fat-suppressed sequence showing a focal occlusion at the junction of the UA and the SPA straight arrow and a tenosynovitis of the flexor digitorum tendons curved arrow. The UA was otherwise preserved. HAVS is substantially underrecognised.

This underdiagnosis is problematic because early recognition and management of this condition are crucial for preventing progression and improving prognosis.

Management involves reduction of vibration exposure, avoidance of cold conditions, smoking cessation, and medication. The persistent median artery may be the site of an occlusion or an aneurysm that causes carpal tunnel syndrome Fig.

This pathology is rare and its mechanism is unclear. Persistent median artery occlusion in a year-old woman. Axial T2-weighted MR image showing an occlusion of the persistent median artery straight arrow and a bifid median nerve arrowheads.

Note also the small median artery satellite veins dotted arrows. Arterial complications result from inadvertent and often repeated arterial puncture during attempted venous access and can lead to acute vascular emergencies.

Vascular complications are common in people who inject drugs. They can occur locally at the injection site or at a distant location and may be arterial or venous in nature [ 49 ]. Various offending agents have been described, including temazepam, flunitrazepam, zolpidem, heroin, midazolam, cocaine, and buprenorphine [ 51 ].

Crushed pills lead to a significantly higher incidence of amputation compared with pure drug substances [ 50 ]. Associated infections are common and represent a poor prognostic factor. A multimodal imaging strategy is often required in the assessment of these vascular complications, typically involving a combination of ultrasound and CT Fig.

Vascular complications may manifest as injury to the vessel wall, pseudoaneurysm or arterial thrombosis with resultant ischaemia or haematogenous spread of a pathogen from the injection site. CT is the imaging modality of choice for mycotic aneurysms. Gas within the aneurysm is a rare but characteristic sign, which is best seen on CT.

Additional imaging features more commonly seen on CT include a lobulated vascular mass, an irregular and poorly defined arterial wall, peri-aneurysmal soft tissue stranding, and oedema. In addition to the risk of rupture, mycotic aneurysms may also lead to the development of arteriovenous fistulae or serve as a source of sepsis or septic emboli [ 49 ].

Thrombolysis and surgical revascularisation may be indicated to restore blood flow to ischaemic tissues in the hand. Pseudoaneurysm of the RA arrow , after intra-arterial injection of buprenorphine, demonstrated with CTA. It typically affects young male smokers younger than 45 years.

Cannabis use has also been implicated. This disease primarily affects small- and medium-sized arteries and veins in the upper and lower extremities, usually beginning in the small distal vessels, resulting in distal ischaemia. As the disease progresses, it may involve more proximal arteries.

Superficial venous thrombosis is also a typical finding. CTA, MRA, or angiography shows involvement of the small- and medium-sized vessels in the upper and lower extremities, including the palmar and plantar arches, the RA and UA, and the digital arteries of the fingers Fig.

The most common imaging findings are segmental occlusive lesions with bridging or corkscrew collaterals around the areas of occlusion.

The disease tends to be more severe distally, with interspersed normal vessels. There should be no evidence of atherosclerosis or other proximal source of emboli e.

dissections or aneurysms [ 53 ]. Vasodilator therapy with iloprost should be considered in acute phases, and bypass surgery may be indicated for limb salvage in critical ischaemia.

SSc is a rare multisystemic disease that preferentially affects middle-aged women. Ischaemic digital ulcers may be responsible for major disability. Although rarely indicated for the evaluation of patients affected by SSc, vascular involvement as well as bone and other soft tissue lesions can be identified on CTA or MRA.

Systemic vasculitides affecting the hand are mostly represented by polyarteritis nodosa PAN. PAN is a systemic necrotising vasculitis that typically affects medium-sized arterial vessels but may also affect small-sized arterial vessels.

PAN is usually diagnosed in middle-aged and older adults. Systemic symptoms can be the only complaints but almost every organ can be involved. Characteristic lesions of the hand include multiple short segment stenoses of the proper and common digital arteries, ectasia, and aneurysms with thickening of the vessels [ 3 ].

Similar findings have been reported for granulomatosis with polyangiitis and eosinophilic granulomatosis with polyangiitis and microscopic polyangiitis. Hand tumours are encountered frequently. Lesions with a vascular origin comprise a wide and heterogeneous spectrum of injuries.

The International Society for the Study of Vascular Anomalies ISSVA classification distinguishes between vascular tumours lesions with cell proliferation and vascular malformations due to an innate disruption of vascular morphogenesis with different pathogenesis, prognosis, and treatment [ 55 , 56 ].

Vascular malformations are classified into low-flow malformations lymphatic, capillary, or most often venous and high-flow malformations arteriovenous fistula and arteriovenous malformation AVM. The soft tissue tumours are classified according to the ISSVA and the World Health Organisation WHO classification of soft tissue tumours [ 57 ].

Some ambiguities still persist because some of these lesions might be classified as tumours or pseudo-tumours and malformations.

In addition, tumours and malformations may also be associated. Furthermore, the current WHO classification of soft tissue tumours recognises three perivascular pericytic tumour types: glomus tumours, myopericytoma, and angioleiomyoma [ 57 ].

MRI provides valuable information for the assessment and treatment of these lesions. Firstly, MRI can determine the nature of many of these lesions.

MRA can also characterise the flow pattern of the vascular malformations to guide treatment towards trans-arterial embolisation for high-flow malformations and percutaneous embolisation for low-flow malformations.

Finally, MRI is essential to define the anatomic extent and involvement of various tissue layers, a distinct advantage over ultrasound [ 7 ].

Dynamic CTA—due to its higher temporal resolution—is also a valuable technique for the evaluation of high-flow malformations Fig. It is important to remember that all vascularised lesions do not necessarily have a vascular origin and that histopathologic analysis remains mandatory in most cases [ 6 , 58 , 59 , 60 ].

Vascular malformations of the hand are common. They are frequently responsible for a visible mass or an enlarged finger. Low-flow malformations are much more frequent than high-flow malformations [ 1 , 5 , 7 , 9 , 14 , 26 , 56 , 61 , 62 , 63 , 64 ].

They may affect the skin with a colour change red or blue. The presence of increased warmth, vascular bruit, or thrill suggests a high-flow component. An AVM is defined by the presence of a nidus.

Both an MRA and MRI are painless and typically noninvasive imabing imaging tools. Doctors may Vasclar one of these flr view bones, tissues, Hormonal health supplement, blood vessels or arteries inside the body. You can schedule your MRI or MRA here at Health Images, and our board-certified radiologist will read your images. Our technologists are skilled at helping you feel comfortable and relaxed during your MRI or MRA. An MRI stands for magnetic resonance imaging. MRI for vascular imaging

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4 thoughts on “MRI for vascular imaging

  1. Entschuldigen Sie, was ich jetzt in die Diskussionen nicht teilnehmen kann - es gibt keine freie Zeit. Aber ich werde befreit werden - unbedingt werde ich schreiben dass ich in dieser Frage denke.

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