|IMAGES IN VASCULAR SURGERY
|Year : 2021 | Volume
| Issue : 5 | Page : 72-74
Lower limb vascular anomalies and malformations with contrast-enhanced magnetic resonance angiography: A case series
S Krishna Kiran1, PC Shaji2, Sunil Rajendran3, TN Gopinath2, J Jagdish4
1 Department of Radiodiagnosis, Father Muller Medical College, Mangalore, Karnataka; Dr Shaji's MRI and Research Centre, Kozhikode, Kerala, India
2 Dr Shaji's MRI and Research Centre, Kozhikode, Kerala, India
3 Department of Vascular Surgery, Star Care Hospital, Kozhikode; Department of Vascular Surgery, MES Medical College, Perinthalmanna, Kerala, India
4 Dr Shaji's MRI and Research Centre, Kozhikode, Kerala, India; Department of Radiology, Al Rahba Hospital, Abu Dhabi, UAE
|Date of Submission||01-May-2021|
|Date of Acceptance||20-May-2021|
|Date of Web Publication||30-Aug-2021|
S Krishna Kiran
Department of Radiodiagnosis, Father Muller Medical College, Mangalore, Karnataka; Dr Shaji's MRI and Research Centre, Kozhikode, Kerala
Source of Support: None, Conflict of Interest: None
Contrast-enhanced magnetic resonance angiography is a valuable technique in the assessment of vascular anomalies of the lower limb. This is an ideal investigation in children and young adults as it is non-invasive and poses no radiation risk. We present a series of cases to highlight this.
Keywords: Contrast-enhanced magnetic resonance angiography, popliteal artery entrapment, sciatic artery, vascular malformation
|How to cite this article:|
Kiran S K, Shaji P C, Rajendran S, Gopinath T N, Jagdish J. Lower limb vascular anomalies and malformations with contrast-enhanced magnetic resonance angiography: A case series. Indian J Vasc Endovasc Surg 2021;8, Suppl S1:72-4
|How to cite this URL:|
Kiran S K, Shaji P C, Rajendran S, Gopinath T N, Jagdish J. Lower limb vascular anomalies and malformations with contrast-enhanced magnetic resonance angiography: A case series. Indian J Vasc Endovasc Surg [serial online] 2021 [cited 2021 Dec 1];8, Suppl S1:72-4. Available from: https://www.indjvascsurg.org/text.asp?2021/8/5/72/324944
| Introduction|| |
Vascular anomalies of the lower limb present significant diagnostic and therapeutic challenges. Incidence of vascular malformations is 1.5%. Of these 39.22% occur in the lower limbs. Clinical history and physical examination remain essential in diagnosis but can underestimate their nature and size, with improvements in imaging playing an important role.
Several arterial variations also noted in the lower limb. Persistent sciatic artery (PSA) and popliteal artery entrapment are the more clinically significant arterial variations.
Magnetic resonance angiography (MRA) is considered an excellent noninvasive technique for assessment of lower limb arteries, approximating results of catheter angiography. Several types of MRA have been described.
There are noncontrast MRA techniques such as time of flight MRA (TOF-MRA) and phase contrast MRA (PC-MRA). In general, these are prone to several artefacts and lack required high resolution in the lower limb.
Contrast-enhanced MRA (CEMRA) is a rapid technique and produces high contrast images. Initially, scout images are taken and careful planning is done. With the help of real-time bolus monitoring software, contrast acquisition is triggered in arterial bed. Pre and postprocessing techniques are used to suppress background structures.
Dynamic CEMRA is a recent development, especially useful in the assessment of vascular malformation. It gives sequential information about arterial, venous, and capillary phases of a vascular malformation. Time-resolved imaging of contrast kinetics (TRICKS) is a commonly employed dynamic CEMRA technique. [Table 1] lists the various MRI techniques used in assessment of vascular anomalies
|Table 1: Presents various magnetic resonance techniques used in the assessment of vascular anomalies|
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Vascular malformations can be classified as low flow or high flow on the basis of hemodynamic flow characteristics. Malformations with arterial component are considered high flow, those without arterial components are considered low flow. High-flow malformations include macrofistulas and arteriovenous malformations with nidus. Low-flow malformations include venous, capillary, and lymphatic malformations.
Computed tomography angiography (CTA) is an alternative technique to CEMRA. There is radiation risk associated with CTA as most patients with congenital anomalies and vascular malformations of arteries are younger. Dynamic technique also is not possible with CTA.
Ultrasonography with color Doppler is an easily available tool to assess superficial vascular malformations. However, deeper vascular malformations cannot be easily assessed and also operator-dependent.
| Technique|| |
We perform CEMRA as a three-stage moving table bolus chase technique. First stage covering the infrarenal aorta, iliac arteries, and upper thigh, second stage rest of the thigh, third stage covering popliteal and infrapopliteal arteries.
Single injection of 15 ml of gadobenate dimeglumine is given in peripheral veins. CARE BOLUS technique (Siemens Erlangen Germany) is employed for triggering of MR acquisition.
TRICKS is the dynamic CEMRA technique employed by us. It shows images of malformation in quick succession. Arterial feeders, size of arteriovenous malformation, capillary phase, and draining veins are depicted in this technique. It needs about 7 ml of gadobenate dimeglumine to be injected intravenously. 1.5T MRI (Avanto Siemens Erlangen Germany) using phased array coils is utilized for performing CEMRA.
| Cases|| |
- Fifty-five-year- old male presenting with pulsatile swelling in left buttock diagnosed as bilateral persistent sciatic arteries with aneurysm on the left side [Figure 1]
|Figure 1: Contrast-enhanced magnetic resonance angiography (a) shows bilateral persistent sciatic arteries and the entire lower limb arterial tree. The termination of the superficial femoral artery in the thigh (black arrow) and continuation of the sciatic artery as popliteal artery can be seen in this image. Arrow with white outline points to the aneurysm in the left persistent sciatic artery. Closer view of aneurysm (b), arrow points to aneurysm|
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The persistence of the embryonic sciatic or axial artery as the major arterial channel to the lower limb is an uncommon but significant anomaly. On CEMRA, it is seen as continuation of the internal iliac artery. Furthermore, it is prone to aneurysm formation in the buttock. It has a prevalence of 0.03%–0.06%, 12%–32% are bilateral. A classification scheme has been proposed for sciatic artery. Type 1 is complete PSA with normal femoral artery, type 2 is complete PSA with incomplete femoral artery development, type 3 is incomplete PSA with only proximal part being present and normal femoral artery, and type 4 is incomplete PSA with the distal part of PSA being present and normal femoral artery. This case belongs to type 2 category.
- Twenty-five-year-old male with claudicating pain right lower limb and diagnosed as bilateral popliteal artery entrapment syndrome with high-grade stenosis right side
Popliteal artery entrapment syndrome is a developmental anomaly that results from abnormal relationship of popliteal artery to gastrocnemius or, rarely an anomalous fibrous band or popliteus muscle. This results in deviation and/or extrinsic compression [Figure 2]. True prevalence of PAES is unknown. In young patients with claudication, 60% of cases may be due to PAES.
|Figure 2: Contrast-enhanced magnetic resonance angiography (a) shows the medial deviation of bilateral popliteal arteries and high-grade stenosis in the right popliteal artery (shown by larger arrow), left popliteal artery is of normal caliber, however, shows medial deviation, shown by small arrow. (b) Shows closer view of stenosis in the right popliteal artery|
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- An eleven-year-old female child with right foot swelling since birth and diagnosed as high flow vascular malformation [Figure 3]
|Figure 3: Time-resolved imaging of contrast kinetics of the foot shows enlarged arteries, filling in both arterial and venous phase (a-c), also early filling of enlarged veins consistent with high flow vascular malformation. Arrows point to site of vascular malformation|
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Vascular malformations are subcategorized on their flow dynamics as low-flow malformations and high-flow malformations. Any malformation with arterialized flow is considered as high-flow malformation.
As mentioned earlier dynamic MRA or TRICKS is necessary for the evaluation of vascular malformations. This technique allows the acquisition of data set in seconds, hence clear separation of arterial and venous phases is possible.
Time-sensitive MRA allows highly sensitive and specific discrimination between high flow and low flow malformations. DSA is generally performed only if interventional treatment is planned.
Other MR features of high-flow vascular malformations are the presence of flow voids, enlarged arteries, and draining veins. Flow voids refer to lack of signal on T1, T2 images indicates fast-moving blood in relation to blood vessels.
- Fifteen–year-old girl with long-standing thigh swelling and diagnosed low-flow vascular flow malformation [Figure 4].
|Figure 4: Coronal shor t tau inversion recovery image (a) shows hyperintense superficial swelling in the left upper thigh. Time-resolved imaging of contrast kinetics of thigh arterial phase (b) shows no increased vascularity. Delayed phase (c) shows faint blush in the lesion, shown by the arrow|
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Low-flow vascular malformations are characterized by gradual filling on dynamic MR angiogram. Other characteristics include bright signal on T2, short-tau inversion recovery sequences, lack of flow voids, normal caliber feeding arteries, and draining veins.
In summary, CEMRA, particularly dynamic technique is useful in assessing angioarchitecture of vascular malformations. It helps in identifying type of vascular malformation and arterial feeders and venous drainage. CEMRA can also be a roadmap for assessing anatomical variations of the lower limb arterial tree.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]