Case Studies

Breast enhancing lesions

MRI lexicon: Morphology of contrast enhanced breast lesions

 

This new MRI lexicon provides and evaluation of the breast MRI scans and integrates dynamic enhancment properties of the breast lesions. Generally speaking, the cost of MRI breast cancer screening is quite excessive and has not proven to be dramatically more beneficial thans screening mammograms and ultrasound. However, contrast enhanced breast MRI can determine whether a lesions is cancerous or benign with a very high degree of sensitivity. (The specificity of breast cancer screening MRIs is not as high, however). The image below shows an early phase contrast-enhanced T1 weighted breast MRI, with mild enhancement, which is suggestive of a benign lesion like fibroadenoma.

Morphology of enhancing breast lesions MR images

When a breast lesion is ‘enhancing’ there are various decriptive criteria that the radiologist will use in assessment. The first descriptive criteria describes the lesion either as a focus, a mass, or a non-mass, based on the type of enhancment being seen.

 

Morphology
Focus
Mass: margin, shape, pattern of enhancement
Non-mass:
linear smooth. irregular, crumpled
segmental homogenous,heterogeneous,clumped
regional homogenous,heterogeneous,clumped
diffuse homogenous,heterogeneous,clumped

 

Morphological description of a ‘focus’ contrast enhanced breast MRI

A focus is basically a tiny spot or ‘dot’ of enhancment, which is generally round and smooth and without ‘mass effect’. (Mass effect defines displacement of mass, which would likely be caused by a growth or nodule )

A ‘focus’ or ‘focal enhancment’ is generally something smaller than 5mm. Since it is so small it cannot really be classified morphologically. Foci (multiple dots) can also have a chaotic effect in the analysis of the ‘enhancment kinetic curve’ (on account of the volume averaging effect with the surrounding normal tissues) Usually, an enhancement focus will be the result of a benign bresat lesions such as papilloma, small fibroadenoma, or generic fibrocystic change. It could also be indicating an intramammary lymph node. However, enhancement foci due rarely show as the result of focal DCIS or even a very small invasive breast cancer.

The subsquent management of a ‘focal enhancement’ is a bit of a judgement call. Most radiologists would tend to consider a biopsy as uneccesary (breast lesions smaller than 5mm are caused by breast cancer only about 3% of the time.) But, if there are corresponding results from mammography and ultrasound and the patient is already considered ‘high risk’, a biopsy might be performed.

Morphological description of a ‘non mass’ with contrast enhanced breast MRI

 

A ‘Non-mass-like’ enhancement is will be mostly characterized by the distribution pattern of the enhancements, whether they are linear, focal, segmental, regional, in multiple regions, diffuse, or ductal. The distribution pattern of non-mass-like enhancement can also be further defined according to ‘internal’ characteristics. These internal characteristics would include observations as to whether the enhancement was homogeneous, heterogeneous, clumped, stippled/punctate, or reticular/dendritic. The radiologist will also note whether or not the enhancement is symmetric or asymmetric between both breasts. The distribution pattern, margins, shape, and internal enhancement patterns all help determine whether or not a non-mass breast lesion is benign or malignant.

 

To describe an image finding as a ‘non-mass’ seems a little bit ambiguous. What this means is that on the contrast enhanced image, there is an enhancment pattern which is distinct from the normal surrounding breast parenchyma, but ther is also no ‘space-occupying’ effect. Invasive ductal carcinoma will tend not to show as a ‘non-mass’ enhancement, but invasive lobular carcinoma and DCIS might. Other lesions that may present with a non-mass-like enhancement are focal adenosis, fibrocystic breast changes due to hormonal stimulation, and inflammatory breast conditions.

The images below are of a pre-contrast and post-contrast enhanced subtraction breast MRI. Note the ductal clumped ‘focal’ pattern.

This would be considered a ‘non-mass-like’ contrast enhancement morphology, and is probably suggestive of lobular carcinoma in situ.

Interestingly, no estrogen receptor positive breast cancers will present in a non-mass-like enhancement, and less than 20% of estrogen receptor negative invasive ductal cancers will show non-mass-like enhancement.

 

Morphological description of a ‘Mass’ on contrast enhanced breast MRI

A lesion found during MRI contrast enhancement is described as a ‘mass’ when it seems to occupy space in three dimensions. Breast masses are then characterized by shape (round, oval, lobulated, irregular), by margin (smooth, irregular, spiculated), and also by ‘internal mass enhancement’ characteristics. These are terms and indicators which describe the manner in which the contrast enhancement is obserbed, including whether it is homogeneous or heterogeneous, if there is rim enhancement, dark internal septations, enhancing internal septations, or central enhancements.

 

A “Homogenous enhancement” pattern will tend to show confluent uniform enhancement within the entire mass. A “heterogeneous” breast lesion enhancement tends to be non-uniform and with a variable signal intensity. The term “Rim enhancement” refers to a more pronounced enhancement towards the periphery of the breast lesion than the center. “Dark internal septations” are actually non-enhancing lines within a breast mass, while the term “enhancing internal septations” refers to enhancing lines within a breast mass. And, obviously, a “central enhancement pattern” will show a more pronounced enhancement at the center of the mass.

 

Amongst various breast lesion shapes observed with MRI contrast enhancement, the highest agreement among observers is that an ‘irregular shape’, tends to suggest breast cancer, while a lobulated shape, tends to suggests fibroadenoma. The two MRI scans shown below reveal invasive lobular breast carcinoma. In the first image, there is some indication of unusual growth in the right breast, but nothing dramatically different from the right breast.

However, the contrast enhanced ‘subtraction’ image clearly shows a spiculated mass, and additional linear enhancment extending all the way to the nipple.

 

Histopathological Association of enhancing masses

Among all the contrast-enhancing features visualized with MRI, margin assessment is probably the most important characterization of a breast mass and has a very high predictive value. Breast masses with smooth margins are almost always indicative of benign disease. (Between 97% and 100% of breast masses with smooth margins turn out to be benign according to some studies.) Lobulated masses with non-enhancing septations and poorly enhanced lobulated masses are also usually benign, and tend to represent fibrocystic changes or fibroadenoma.

Contrast enhanced MRI features typical of breast fibroadenomas

Fibroadenomas can actually exhibit a variety of enhancements, depending of whether there is hormonal stimulation of the breast and on the degree of fibrosis present. In ‘myxoid’ fibroadenomas, the contrast enhancement is actually quite strong but it lingers into the late phase, unlike breast cancer which tends to ‘wash-out’ in the late phase. Fibroadenomas also tend to have a homogeneous internal enhancement pattern, which also has a high predictive value for benign breast lesions. However, a homogeneous internal contrast enhancement pattern is occassionally associated with invasive breast cancer as well, so it will likely still be treated with some suspicion.

The images above and below show a pre-contrast T1-weighted breast MRI, and then a contrast-enhanced subtraction image. One notes an irregular shaped mass with spiculated margins and rim enhancement, which is highly suggestive of invasive breast cancer.

Phyllodes tumors also have a unique DCE MRI profile

In Phyllodes tumors, which constitute less than 1% of breast tumors, contrast enhancing breast MRI tends to reveal a lobulated mass with non-enhancing internal septations. Phyllodes tumors also tend to have more heterogeneous internal structures than true breast cancer lesions.

 

Morphological presentations of breast cancers based on hormone receptor status

The main morphological presentation of most ‘triple negative’ breast cancers ( negative for HER-2 receptor, progesterone receptor, and estrogen receptor) is a mass ( about 97% of the time) Her-2 positive breast cancers tend to have more multiple mass lesions than Her-2 negative (about 57% and 15% respectively). Breast cancers that are estrogen receptor positive tend to present slightly more frequently as a mass, as compared to estrogen receptor negative breast cancers (100% and 82% respectively), but there is little difference in lesion multiplicity based on positive or negative estrogen receptor status.

 

Additional MRI contrast enhancement features suggestive of breast cancer

Enhancing breast masses with septations, and also enhancing lobulated masses without septations, are both highly suggestive of malignant breast cancer. Breast masses with marked to moderate heterogenous enhancement with wash-out kinetics are also highly suggestive of malignant breast cancer, but not to specific types of breast cancer. The pre-contrast MRI scan below shows a suspicious lesions which likely indicates invasive lobular breast carcinoma.

The post-contrast ‘subraction’ image of the same lesion below clearly reveals a heterogenous pattern of enhancment, consistent with invasive lobular carcinoma.

Irregular, spiculated margins and rim enhancement are suggestive of breast cancer

Irregular masses, and those this spiculated margins or rim enhancement have a positive predictive value for malignant breast cancer in the 80%-100% range, with infiltrating ductal carcinoma being the most common breast cancer type found.

Rim enhancement is more frequently observed in larger tumors of a higher histological grade. Rim enhancement is essentially a clearly brighter or enhanced ‘ring’ around the periphery of the lesion, which suggests different tissues and blood demands on the in the center vs the rim of the lesion. When rim enhancement appears in a small breast tumor (occuring about 20% of the time), it is highly suggestive of breast cancer.

 

Contrast enhancing breast lesions with spiculated margins are most often, but not always, associated with malignant carcinoma. Most commonly they are found with invasive ductal carcinoma, but occur with tubular breast carcinoma as well.Invasive lobular breast carcinoma and DCIS can also manifest as irregular masses or masses with spiculated margins. However, benign lesions like radial scars can also show spiculated margins, so this is a situation in which the assessment of ‘enhancement kinetics’ (the realtime observation of the increases and decreases in contrast enhancement) can help determine a more conclusive diagnosis.

Distribution patterns of non-mass-like enhancements in breast MRI

The distribution pattern of a non-mass-like enhancement can take many forms. Non-mass-like breast MRI contrast enhancing patterns can be described as focal, linear, segmental, ductal, regional, diffuse, and with multiple regions.

A ‘focal’ area of a non-mass-like enhancement would typically be defined as a single, small and confined abnormal enhancing area occupying less than 25% of a given breast quadrant. (Note, this is a different finding than a ‘focus’, which by definition will measure less than 5mm.) An area of ‘focal’ non-mass-like contrast enhancement will quite often have fat or nomral glandular tissue interspersed between the abnormally enhacing components.
A ‘linear‘ enhancment pattern involves enhancement along a ‘line’, but one not conforming to a ductal pattern. A linear enhancement pattern when seen on a three dimentional image will appear as a ‘sheet’ and not a line, or may extend across the breast in a non-ductal distribution pattern.

The images below show a precontrast and post contrast enhanced subtraction breast MRI. The contrast enhanced image shows a non-mass-like linear enhancement.

The enhancement pattern, suggesting invasive breast cancer, does not conform to a ductal structure, and is therefore simply described as ‘linear’.

Contrast enhanced breast MRI may reveal multiple foci of dcis, hidden to mammography

The two MRI scans above and below reveal invasive ductal carcinoma and also multiple foci of ductal carcinoma in situ. There also appears to be some lymphatic invasion in the nipple areolar complex. One also notes a branching ductal pattern toward the nipple, with skin thickening.

Multiple foci of non-mass-like DCIS may be difficult to spot using conventional mammography and ultrasound.

‘Ductal non-mass-like enhancing breast lesions follow a breast duct system

A non-mass-like contrast enhanced distribution of a breast MRI is described as ‘ductal’ when it appears in a linear or linear branching which follows one or more ducts. Usually these patterns will radiate towards the nipple. There is not always a clear separation between linear enhancement and ‘ductal’ enhancement, and sometimes the terms are used to mean the same thing. However, a ductal enhanecment pattern of non-mass-like contrast enhanced MRI is more specific, and indicates the presence of a suspicious breast lesion following a breast duct. Ductal contrast enhancement is thought to have a positive predictive value for breast cancer ranging from about 26% to 59%. Most commonly, it represents ductal carcinoma in situ, but might also indicate atypical ductal hyperplasia, lobular carcinoma in situ, or other benign breast conditions. Approximately 50% of these MRI non-mass-like linear and ductal enhancement distributions turn out to be benign.

 

The segmental non-mass-like enhancment pattern apexes at the nipple

A non-mass-like contrast enhanced MRI breast lesion is described as ‘segmental’ when it appears in a cone or triangle shape, with an apex at the nipple. A segmentally enhanced non-mass-like lesion will usually represent the substantial involvement of a single braching duct system.

The positive predictive value for breast cancer of a segmental contrast enhanced breast lesion is quite high, ranging from about 68% to near 100%. Segmental contrast enhancement is one of the most frequent manifestations of ductal carcinoma in situ. Surprisingly, for around 17% women with ductal carcinoma in situ discovered as a segmentally enhancing MRI image, there was no abnormality noted on a breast cancer screening mammogram.

A segmental contrast enhanced breast lesion is occasionally found to be invasive lobular carcinoma, but most commonly it is associated with infiltrating ductal carcinoma. About 67% of non-mass-like lesions in a segmental distribution turn out to be breast carcinoma.

The two images below are of a pre and post contrast enhanced breast MRI. The second ‘subtraction’ image reveals a clumped segmental distribution pattern, likely indicative of infiltrating ductal carcinoma.

Internal Patterns of breast MRI contrast enhancement

There are additional descriptors for the enhancement patterns of MRI lesions, which focus on the overall appearance visually. These include homogenous, heterogeneous, stippled/punctuate, clumped and reticular/dendritic.

A ‘homogenenous’ contrast enhancement pattern is essentially a uniform and confluent enhancement, while a ‘heterogenous’ enhancement is more random and non-uniform. Areas of heterogenous enhancment will typically be separated by areas of breast parenchyma or fat. The likelihood of a homogeneous enhancement pattern as representing breast cancer would be about 67%, which is quite high. A heterogenous enhancement pattern will indicate breast cancer about 54%-68% of the time.

 

The ‘stippled‘ or ‘punctate‘ pattern of enhancement refers to multiple tiny dot-like lesion, 1-2 mm in size only. They will appear as similarly punctuate foci scattered throughout a given breast area. Stippled and punctate enhancements will usually not conform to a duct. Most of the time, a stippled or punctate enhancement pattern will indicate either normal breast tissue, or benign fibrocystic breast changes. The changes of a stipled enhancement patterns being malignant breast cancer is about 25%.

 

A “Clumped’ pattern of breast MRI contrast enhancement basically refers to an ‘aggregate of enhancing masses or foci more-or-less in a ‘cobblestone’ pattern. A clumped pattern is considered suspicious for DCIS or invasive ductal carcinoma. In fact the chances of a clumped breast MRI enhancement pattern representing DCIS or breast cancer ranges from about 41% up to 88%, however almost 90% of these cancers turn out to be DCIS. It is quite typical for the clumped or beaded enhancement pattern reviled by breast MRI to be caused to randomly ‘heaped-up’ tumor cells in a breast ducts which is expanding due to DCIS.
A ‘reticular’ or ‘dendritic‘ enhancement pattern is one in which some glandular breast tissue has undergone ‘involution’, leaving tissue strands among strands of fat.

Symmetric enhancment is self evident, referring to a ‘mirror image’ contrast enhancement pattern in both breasts, and will almost always be indicative of benign breast changes. An ‘asymmetric non-mass-like contrast enhancement pattern is simply more pronounced in one breast than the other.

Segmental contrast enhanced breast MR images often show a pattern growing towards the nipple

The images below show a pre and post-contrast subtraction MRI, which reveal a segmental enhancement pattern.Because the enhancement pattern appears to be moving towards the nipple, it would be consistently described as a segmental non-mass-like contrast enhanced pattern. This paritular legion is most likely invasive lobular breast carcinoma.

“Regional” pattern of contrast enhancement involves a broader area

When a contrast enhanced MRI of a breast lesion is described as ‘regional‘, this implies the involvement of a broader area, and typically not conforming to a ductal distribuation. Regional contrast enhancement tissues tend not to be as distinct from the surrounding tissues when compared to previous patterns. Usually, regional enhancment is patchy or ‘geographic’ ( almost like a map) in appearance, and will lack convex borders. Most of the time, regional enhancement represents a benign lesion such as fibrocystic change, but it can indicate a cancer growth as well. The likelihood of regional enhancement being breast cancer is in the order of 21%, and most often the cancer presents as DCIS or infiltrating lobular carcinoma, and rarerly as invasive ductal carcinoma.

The two images below are a pre and post-contrast-subtraction MR image demonstrating regional enhancement.

Though faint, the patchy enhancement in the left breast would likely indicate fibrocystic change.

Contrast enhanced breast MRIs are described as ‘multiple‘ if there are at least two or more large volumes of tissues not conforming to a ductal distribution pattern, and, which are separated by either normal breast tissues or fat. Similarly, an enhancement pattern may be described as ‘diffuse‘ if there are widely scattered yet more-or-less evenly distributed enhancements appearing through the breast fibroglandular tissue. Generally speaking, both diffuse and multiple regions of MRI contrast enhancement will tend to represent benign proliferative changes. However, it is not uncommon for multicentric breast carcinoma such as invasive ductal carcinoma or invasive lobular carcinoma, to also show a multiple of diffuse distribution.The contrast enhanced subtraction MRI below reveals a symmetrical diffuse enhancment in both breasts, likely indicative of benign breast fibrocystic changes.

Neurofibromatosis

MRI

Neurofibromatosis is a group of heterogeneous conditions. According to the National Institutes of Health (NIH) only two types of neurofibromatosis are defined: neurofibromatosis type 1 (NF1) also called von Recklinghausen’s disease; and neurofibromatosis type 2 (NF2) or bilateral eighth nerve schwannomas syndrome. The definition of “peripheral” and “central” neurofibromatosis, referred in the past to NF1 and NF2, respectively, has now been abandoned since the two conditions often have central and peripheral manifestations together.

Neurofibromatosis Type 1 (NF1)

NF1 is an autosomal dominant disorder with high penetrance but variable expressivity.

The gene responsible is on the long arm of chromosome 17 and normally acts as a tumour-suppressor oncogene. The lack of both copies of the gene induces the growth of a variety of neoplasms and non-neoplastic lesions. The major target organs are both peripheral (PNS) and central (CNS) nervous system and the skin, but virtually widespread multiple organ system involvement occurs. NF1 is far more common than NF2 and affects approximately 1 in every 2,000 – 3,000 births.

The diagnosis is based on physical examination, neuroimaging of the brain (and probably of the spine), slit-lamp examination of the eyes and genetic testing.

In most individuals the cutaneous findings are prominent and include caf-au-lait spots (CAL), usually becoming evident during the first year of life, superficial neurofibromas, which begin to appear at puberty, and axillary or inguinal freckling. Lisch nodules that represent iris hamartomas start to appear in childhood and are found in almost all adult patients on slit-lamp examination.

MRI

CNS characteristic manifestations, well documented by MR, include true neoplasms (all coming from astrocytes and neuronrs), as well as dysplastic and hamartomatous/heterotopic lesions. The most common CNS tumours are optic nerve, tectal plate and brain stem gliomas (usually pilocytic astrocytoma or low-grade glioma). In one third of patients, neurofibromas affecting intraorbital and facial branches of the cranial nerves (III – VI) and/or diffuse plexiform neurofibroma of the face and eyelids is present.

Intracranial dysplastic lesions appear as multiple bright foci on T2-weighted MR images in the brain stem, cerebellar white matter, dentate nucleus, basal ganglia, periventricular white matter, optic nerve, and optic radiations. They most probably represent either abnormal myelination or hamartomas. Unlike neoplasms these lesions do not show mass effect, oedema, contrast enhancement or haemorrhage on MR images. Basal ganglia T1-weighted hyperintensities seem to represent ectopic Schwann cells. Other classic features of NF1 are benign peripheral nerve sheath tumours (spinal root/dumb-bell neurofibromas), kyphoscoliosis, lateral thoracic meningocele, dysplastic enlargement of spinal foramina, sphenoid wing dysplasia that is one of the “distinctive bone lesions” of the disease and causes pulsatile exophthalmos in 5 – 10% of patients, pseudarthrosis, thinning of long bone cortex, macrocephaly, vascular dysplasias and endocrine tumours.

MRI

The diagnosis of NF1 is established when two or more of the anomalies listed in Table I are present.

Neurofibromatosis, Table 1. Anomalies seen in NF1.

1. Six or more caf-au-lait spots > 5 mm
2. Two or more neurofibromas of any type or one plexiform neurofibroma
3. Two or more Lisch nodules (iris hamartomas)
4. Freckling in the axillary or inguinal areas
5. Optic nerve glioma
6. A distinctive bone lesion such as sphenoid wing dysplasia
7. First degree relative with NF1

 

Neurofibromatosis Type 2 (NF2)

NF2 is an autosomal dominant disorder with high penetrance due to a defect of chromosome 22. Its frequency is approximately 1 in 35,000 births. Clinical manifestations develop only in the second or third decade of life. Cutaneous manifestations are much less frequent in NF2 than in NF1. CNS lesions that develop in nearly all affected individuals include: intracranial tumours of schwann cells and meninges, nontumoral intracranial calcifications (choroid plexus), and spinal cord and nerve root neoplasms (mainly ependymomas, schwannomas and meningiomas).

Bilateral acoustic schwannomas are present in about 95% of affected patients and are considered the hallmark of the disease. They are seen on both CT and MR containing cystic degeneration and calcifications. On MR schwannomas are hypo-isointense on T1-weighted and hyperintense on T2-weighted images with strong, inhomogeneous enhancement after contrast administration. All the other cranial nerves (except the olfactory and optic nerves) can be involved by schwannomas, most frequently the trigeminal nerve.

MRI

Spinal cord ependymomas, multilevel spine meningiomas and schwannomas along the exiting nerve roots are nicely visualized by MR. Peripheral nerve roots schwannomas appear as well encapsulated masses, isointense on T1-weighted and hyperintense on T2-weighted images, with typical contrast enhancement. Spinal bony abnormalities secondary to tumours are reported in NF2, e.g. posterior vertebral scalloping and enlargement of neural foramina. No dural dysplasia are found, contrary to NF1. Other reported anomalies are: presenile posterior subcapsular/capsular cataracts (85%), peripheral cortical lens opacities and agenesis of the internal carotid artery.

Neurofibromatosis, Table 2. Anomalies seen in NF2.

1. Bilateral eighth nerve masses at imaging studies
2. Unilateral eighth nerve mass plus two of the following:
meningioma, schwannoma of any cranial neves, presenile posterior subcapsular/capsular cataracts

Vertebral Haemangioma

Clinical History: A 46 year-old female with a history of breast cancer presents with low back pain. (A) Sagittal T2-weighted, (B) sagittal T1-weighted and (C) axial T1-weighted images are provided. What are the findings” What is your diagnosis?
A
B
C
Findings
AThe T2-weighted sagittal image shows a lesion of increased signal intensity replacing the entire L2 vertebral body. Coarse vertically oriented trabeculae are present (arrows).
BThe T1-weighted sagittal image reveals that the L2 vertebral body lesion (arrow) is of increased signal intensity, similar to that seen on the T2-weighted image.
CThe T1-weighted axial image demonstrates the coarse trabeculae on end surrounded by fat signal, resulting in a ‘salt and pepper” appearance (arrow).
Diagnosis
Vertebral Hemangioma
Discussion
Hemangiomas of the vertebral bodies are common benign vascular tumors. Vertebral body hemangiomas are the most common tumor of the spinal axis and occur in approximately 10-20% of adults. Most of the lesions occur in the thoracolumbar spine. The majority of the hemangiomas seen with imaging studies are asymptomatic and incidental findings. Some authors report a 2:1 female/male predominance, but others report an equal incidence in males and females, and that only the symptomatic lesions are more common in females. Approximately 20-30% of hemangiomas are multiple, particularly in the thoracic spine. The lesions are usually rounded with discrete margins, unless a pathologic fracture has occurred. They can vary from being subcentimeter in size to replacing the entire vertebral body. The lesions are most commonly limited to the vertebral body, but 10-15% extend into the posterior elements. Hemangiomas seldom arise primarily from the posterior elements. The majority of vertebral body hemangiomas have no associated abnormalities, but rarely they are associated with an autosomal dominant syndrome that includes cerebral cavernous malformations.Osseous hemangiomas are slow growing hamartomas. Histopathologically they consist of thin-walled blood vessels and sinuses lined by endothelium and interspersed among sparse longitudinally oriented trabeculae of bones. The dilated vascular channels are set in a stroma of fat. More aggressive hemangiomas contain less fat and more vascular stroma, and may look similar to a metastatic lesion on imaging studies.Hemangiomas have typical appearances with routine radiography, CT and MR. On plain radiographs, hemangiomas often have a vertically striated appearance due to thickening of bony trabeculae. This appearance has been described as “corduroy cloth” or “jail bar” and the overall density of the vertebral body is decreased due to the presence of fatty marrow. With CT, vertebral body hemangiomas have low attenuation interspersed with thickened bony trabeculae, causing a characteristic “salt and pepper” or “polka dot” appearance on axial images. With MR imaging, the intralesional fat of the hemangioma causes increased signal intensity on T1 weighted MR images. On T2-weighted images, the signal intensity of the hemangiomas also increases because of high water content, and the T2-hyperintensity is typically greater than that of fat, thereby differentiating hemangiomas from focal fat deposition. These signal characteristics also differ from those of metastatic lesions, which have decreased signal intensity on T1 weighted images and increased signal intensity on T2 weighted images. As with CT, the thickened bony trabeculae on MR axial images results in a “salt and pepper” or “polka dot” pattern. The signal intensities of atypical hemangiomas can be indeterminate, but the morphology of the lesion, including the presence of coarse trabeculae, can be used to make the diagnosis (D, E). For more difficult indeterminate cases, CT can be used to problem solve, as CTs are more sensitive to the characteristic osseous remodeling of hemangiomas than MR imaging. If necessary, follow-up examinations can be performed to ensure stability. Only in rare cases is a core biopsy necessary to make the diagnosis.
DThe T1-weighted sagittal image demonstrates an atypical hemangioma within the L1 vertebral body (arrow) with coarse trabeculae, but with relatively little typical fat signal within the lesion.
EThe T2-weighted sagittal image shows a typical appearance with increased signal intensity, well-circumscribed margins and coarsened trabeculae (arrow).
Aggressive hemangiomas typically occur between T-3 and T-9 and commonly involve the entire vertebral body with extension into the neural arch. Aggressive hemangiomas generally have an expanded and indistinct cortex, an irregular honeycombing pattern, and a soft tissue mass. Aggressive vertebral hemangiomas can become symptomatic with growth, which often occurs during pregnancy. Symptomatic pathologic fractures can occur with hemangiomas and compression fractures can lead to myelopathy from cord compression. Symptomatic hemangiomas are usually treated non-surgically with embolization, sclerotherapy or vertebroplasty. Surgery is reserved for cases with cord compression, and radiation therapy may be used following subtotal resection.
FA T2-weighted sagittal view of the thoracic spine reveals multiple typical hemangiomas (asterisks). In the lower thoracic spine, an area of epidural extension (arrow) is identified.
GA contrast-enhanced T1-weighted axial plane image through the hemangioma confirms the epidural extension, and demonstrates the enhancing stroma within the left side of the spinal canal (arrow), displacing the thoracic cord.
Conclusion
Vertebral body hemangiomas are the most common tumors of the spinal axis and in most circumstances are incidental findings. Most hemangiomas are diagnosed based on their characteristic imaging findings, though the diagnosis can be challenging in cases of atypical or aggressive hemangiomas. In such cases, the recognition of vertically oriented coarse bony trabeculae surrounded by fatty stroma, resulting in the “salt and pepper” appearance on axial images and a striated appearance on coronal or sagittal images, is the key to the correct diagnosis. Though rare, aggressive hemangiomas can be symptomatic and pathologic fractures can lead to myelopathy and cord compression. In such patients, MR accurately displays the extraosseous extension of the hemangioma and its effect upon the spinal canal and cord.

Cerebral hemiatrophy

Cerebral hemiatrophy has a variety of causes, and is generally associated with seizures and hemiplegia. Causes include:

  • congenital
    • idiopathic (primary)
    • intrauterine vascular injury
  • acquired
    • perinatal intracranial haemorrhage
    • Rasmussen encephaltitis
    • postictal cerebral hemiatrophy
    • basal ganglia germinoma
    • trauma
    • infection
    • vascular abnormalities e.g. Sturge-Weber syndrome
    • ischaemia
    • hypoxia

Radiographic features

The resultant reduction in cerebral volume, if early enough, can lead to changes in the skull, known as Dyke-Davidoff-Masson syndrome.

Changes within the brain parenchyma typically demonstrate:

  • thinning of the grey matter cortex
  • reduced volume of the underlying white matter
  • + / – reduced / abnormal myelination
  • enlargement of the lateral ventricle
  • reduced size of cerebral peduncle (ipsilateral)
  • reduced size of cerebellar hemisphere (contralateral)

MRI BRAIN

Differential diagnosis

A potential pitfall is assuming the ‘small’ side is the abnormality. Thus hemimegalencephaly or gliomatosis cerebri or widespread cortical dysplasia should be considered.

MRI BRAIN