Ossification of Posterior Longitudinal Ligament (OPLL)

 

Above lateral cervical radiograph and the T2, T1 weighted MR images show thickening and ossification of the Posterior Longitudinal Ligament (OPLL) posterior to C2 and C3 vertebral bodies. The PLL ossification would be seen as hypointense signal intense thickening of the PLL in both T1 and T2 images. Narrowing of the spinal canal with compression of the thecal sac and the cord is present at C2/C3 levels.

Sclerotic Skeletal Secondaries

T1 and T2 hypointense multiple lesions are noted in the dorsolumbar and sacral vertebrae, in the above MR images. These lesions are  hyperintense in STIR images. T1 and T2 hypointense signal intensity is suspicious for sclerotic nature of the lesions. Mild expansion of L3 vertebral body is also noted. No associated paraspinal soft tissue components were seen. Contrast MRI taken showed moderate enhancement in all lesions (not shown). 

Few similar signal intensity lesions are also seen in C6, D1 and D6 vertebral bodies.

CT images are confirmatory. L3 vertebral body lesion is extending to involve both pedicles and extending further into the posterior elements.

The most common cause for sclerotic bone metastases are prostate carcinoma in males and breast carcinoma in females. Occasionally transitional cell carcinoma of urinary bladder, gastric carcinoma, colonic carcinoma, neuroblastoma, testicular carcinoma and lymphoma can produce sclerotic metastasis. Carcinoid tumor of lung also usually result in sclerotic metastatic lesions.

Reference:

Chapman, 6th edition. 

ACL and Lateral Meniscus old avulsion fractures without marrow edema

Clinical history: 40Y M patient with previous history of knee injury, now presenting with lateral joint pain, ROM restriction, locking and sounds. 

ACL tibial attachment appears avulsed and displaced postero-superiorly. No marrow edema seen in the tibial attachment site or in the fragment. Orange arrows point to the avulsed fragment from the tibial intercondylar region, which appears more rounded and corticated.

 

Attachment site of anterior root of lateral meniscus is seen avulsed from the tibia, and is seen displaced slightly laterally from the anterior intercondylar region. No marrow edema was seen. Meniscal avulsion to produce a bony detachment is unusual. The meniscus usually detaches from the cortical surface of bone and is then called as a 'floating meniscus'. (Differential consideration for this would be a meniscal ossicle. But this is commonly seen in posterior horn of medial meniscus and a donor site would not be present in the tibia).

 

Irregular near full thickness cartilage losses of the central portion of lateral tibio-femoral compartment is noted with subchondral marrow edema of both surfaces. Yellow arrow points to the cartilage loss, green arrow to the marrow edema. These in addition to the tiny tibio-femoral marginal osteophytes, favor the development of secondary osteoarthritis. Lateral meniscal extrusion is also noted in the coronal images. Blue arrow(s) shows absence of marrow edema in the tibial intercondylar region, indicating the avulsions are old ones. A small old Segond fracture is also seen in the lateral proximal tibia. 

Prominent horizontal tear (yellow arrow) of posterior horn of medial meniscus is noted extending into the tibial surface and the posterior free margin. A multiloculated cystic area (green arrows) is noted close to the posterior horn of medial meniscus, seen communicating with the tear (orange arrow), suggesting a parameniscal cyst.

A small T2 hypointense intra-articular loose body is noted posterior to the medial femoral condyle.

 T2 oblique sagittal images showing the bony avulsions, the meniscal tear and the parameniscal tear.

Epidermoid cyst of the Cerebello-Pontine Angle (CPA)

Intracranial epidermoid cysts are uncommon congenital slow growing lesions which becomes symptomatic due to the development of mass effect on adjacent structures in the 2nd - 4th decade of life. They are most commonly located in the cerebello-pontine angle in almost 50% of the cases. It is the third most common CP angle mass after acoustic schwannomas and meningiomas.

In MRI these lesions appears almost isointense to CSF but shows a characteristic restricted diffusion. These appear as lobulated lesions that typically insinuates between the adjacent structures and encases the cranial nerves and vessels. Calcification is seen in 10%-25% cases.

Another characteristic feature of epidermoid and MRI is partial suppression sometimes called the dirty appearance in T2 FLAIR images. In rare cases when they are T1 hyperintense they are called as white epidermoid.

The following images are of a 25 year old male patient.

CSF intensity appearance of the epidermoid cyst  is noted in the T1 and T2 weighted images, with a dirty appearance (partial suppression ) in the T2 FLAIR images. Lesion is predominantly located in right CP angle cistern, with extensions into the right cervico-medullary cistern, pre-pontine cistern, sellar-parasellar areas (details mentioned below). 

Mass effect on the right lateral aspect of pons, middle cerebellar peduncle is noted with  displacement to left. Partial effacement of the fourth ventricle is present. No hydrocephalus was seen.

In the SWI image above no blooming artifacts are seen within the lesion. DWI and ADC images show characteristic restricted diffusion, which helps to differentiate the lesion from an arachnoid cyst.

T1 sagittal and T2 coronal images show the mass effect of the lesion on the adjacent brainstem and the right middle cerebellar peduncle. The 3D T2 CISS images show characteristic lobulated appearance of the epidermoid cyst with insinuations in the CSF spaces and encasement of the cranial nerves and vessels.

Lesion shows no post-contrast enhancement.

The video above shows the right CP angle epidermoid cyst in much more detail in the 3D CISS images, which is helpful in determining the extent of the lesion. Diffusion weighted images also shows the extent of the lesion better than the conventional images due to the CSF intensity of the major portion of the lesion in rest of the sequences.

Significant mass effect and marked lateral displacement with stretching of right trigeminal nerve cisternal segment is noted. The lesion is encasing the right VII-VIII nerve complex, cisternal segment of right oculomotor nerve, and partly encasing the cisternal segment right trigeminal nerve. Lateral displacement of the right oculomotor nerve is also noted by the lesion. Superiorly the lesion is extending into the anterior aspect of midbrain, sellar and suprasellar region, partly encasing the right ICA bifurcation and the pituitary infundibulum. It is noted in contact with the right uncus and floor of third ventricle, tuber cinereum and mammillary body. Partial encasement of the basilar artery and its bifurcation is also present.

References:

https://radiopaedia.org/articles/intracranial-epidermoid-cyst
 

Extensor Carpi Ulnaris (ECU) tendinosis with interstitial tear

Extensor carpi ulnaris tendinosis is one of the common causes of ulnar sided wrist pain. Extensor carpi ulnaris passes through a fibro-osseous tunnel (the sixth extensor compartment), lying within a bony groove on the dorsal surface of ulna. ECU is maintained in this groove by the extensor retinaculum and the ECU subsheath. The ECU subsheath is not attached to the tendon.

The ECU originates from two heads, one from lateral epicondyle and other from the posterior middle third of ulna and distally it inserts into the posterior aspect of the base of fifth metacarpal.  

Racquet Sports and golf athletes are at an increased risk of ECU tendon pathology. In non-athletes rheumatoid arthritis is also to be excluded. The pathologies which can affect the ECU tendon includes tenosynovitis, tendinosis, tendon instability and rupture.

The PDFS axial and coronal image above shows mild thickening and intermediate signal intensity of the ECU tendon favoring tendinosis, with thickening and hyperintense signal intensity of the tendon sheath with associated mild soft tissue edema (suggesting tenosynovitis).

Serial axial sections of the wrist (clockwise) shows thickened ECU tendon with irregular shaped hyperintense intrinsic linear signal intensity favoring and interstitial tear.

No subluxation or dislocation of the ECU tendon is noted from the ulnar groove. The ECU subsheath and the extensor retinaculum appears intact. The orange thick arrow corresponds to the retinaculum and the thin green narrow corresponds to the ECU subsheath.

The above T2 axial image of the wrist is also showing the intact ECU subsheath (green narrow).

References: 

1. https://radiopaedia.org/articles/extensor-carpi-ulnaris-tendinopathy
2. https://radsource.us/extensor-carpi-ulnaris-subsheath-injury/

Dilated occipital emissary vein in Idiopathic Intracranial Hypertension

 25Y female who presented with complaints of chronic headache, on examination was found to have bilateral papilledema. An MRI with MR venogram was taken to look for features of Idiopathic Intracranial Hypertension. MRI findings were partial empty sella, with minimal increase in the retrobulbar optic nerve sheath CSF content (not shown). No vertical tortuosity of the optic nerves were seen in the MRI.  

MR Venogram showed mild distal transverse venous stenosis. A dilated occipital emissary vein was noted with diameter of the intraosseous component measuring 4.5 mm and the diameter of the proximal extracranial segment measuring 4.7 mm. Rest of the major intracranial venous sinuses appear normal.

Emissary veins of the skull base and posterior fossa direct the cerebral blood flow into the cervical outflow tracts. These include the condylar (anterior, posterior and lateral) emissary veins, mastoid emissary vein and the occipital emissary vein. The occipital emissary vein is seen near the midline of the squamous occipital bone and it connects the torcula or the distal superior sagittal sinus to suboccipital veins, which further drain into the vertebral venous plexus and / or the deep cervical vein. 

Enlarged occipital emissary veins have been described in craniosynostosis , increased ICT and in thrombosis of transverse sinus or sigmoid sinus. 

Idiopathic Intracranial Hypertension (Syn: Benign intracranial hypertension or pseudotumor cerebri syndrome (PTCS)) are characterized by findings of enlarged empty sella, papilledema, vertical tortuosity of optic nerves, dilated subarachnoid spaces around cranial nerves and dural venous sinus stenosis (usually bilateral distal transverse sinuses). The occipital emissary vein in patients with idiopathic intracranial hypertension may be dilated because it acts as a collateral venous channel and its dilatation is considered a possible marker for IIH.

Reference: Hedjoudje A, Piveteau A, Gonzalez-Campo C, Moghekar A, Gailloud P, San Millán D. The Occipital Emissary Vein: A Possible Marker for Pseudotumor Cerebri. AJNR Am J Neuroradiol. 2019 Jun;40(6):973-978. doi: 10.3174/ajnr.A6061. 

Patellar Dislocation and Relocation (PDR)

20Y old male presented with history of fall and direct injury to anterior knee.

The above axial PDFS images demonstrate the torn medial patello-femoral ligament (MPFL, blue arrow) and the medial patellar retinaculum (orange arrow) more distally. Marrow edema is noted in the medial portion of the patella (green arrow). Lateral patellar tilt, mild to moderate joint effusion and shallow trochlear sulcus angle (145°) ( suggesting trochlear dysplasia) were also noted. The lateral trochlear inclination angle measured approximately 10°.

The two axial and last coronal PDFS images shows the contusion in the lateral femoral condyle, caused due to the impaction by the dislocated patella.

Here the first image is showing the PDFS coronal image in the anterior aspect of the knee, with the arrow pointing to edema in the inferomedial anterior aspect of patella with small a avulsion fragment. Axial and coronal CT bone window images shows multiple small chip/avulsion fractures of the medial patella. In the CT sections of patella appear slightly laterally subluxed. (Note: The small fragment like appearance of the femoral condyles in CT axial section is actually due to the physeal plate, and not fractures).

The above PDFS sagittal image shows injury to the Hoffa's fat pad represented by the yellow arrow heads. The image on the right (T2 sagittal) shows increased Insall-Salvati Index, measuring 1.55, suggestive of Patella Alta. 

The risk factors of patellar dislocation include shallow patellar depth, shallow trochlear sulcus, dysplasia of the femoral condyle or patella, lateral position of the tibial tuberosity, patella alta, patellar dysplasia (nail patella syndrome) , ligamentous laxity (Marfan syndrome, Ehlers Danlos, Down's syndrome and polio) and tight lateral retinaculum.

The most common finding in the patellar dislocation is hemarthrosis or lipohemarthrosis. 

The contusion in the lateral femoral condyle which may be seen up to 80-100% of patients and is considered most specific MR imaging finding of a patellar dislocation. The contusion of the lateral femoral condyle seen in the patellar dislocation/relocation is located more anteriorly, laterally and superiorly when compared to the ACL injury contusion pattern.

Patellar contusion is seen in approximately 40% of the patients and is located in the medial and inferior aspect of the patella, in relation to the attachment of the medial retinacular complex.

The injury pattern characteristic of 'patellar dislocation/relocation' is the so called 'kissing contusions' because of the patella compressing on the lateral femoral condyle during dislocation.

Reference:

Thomas Lee Pope, MR imaging of patellar dislocation and relocation, Seminars in Ultrasound, CT and MRI, Volume 22, Issue 4, 2001,Pages 371-382, ISSN 0887-2171,
https://doi.org/10.1016/S0887-2171(01)90027-7.

Special Thanks to Prasad George, Senior MRI Technologist. 😆

Band Heterotopia (Double Cortex Syndrome)

Clinical History: 6-year-old female child presented with first episode of seizure. Developmental history is within normal limits, excepting mild recent deterioration in an academic performance. 

Below are the MRI brain images of the Child. First image shows axial T2 image and coronal IR image. The green arrows point to the abnormal band of heterotopic gray matter situated between the layers of white matter (yellow arrows). The finding is more apparent in the coronal IR image.

This finding is called as band heterotopia or double cortex syndrome, which is a neuronal migration anomaly, affecting females and is considered a part of the Lissencephaly type I - subcortical band heterotopia spectrum. Children usually present with refractory epilepsy.

The overlying cortex (orange arrows) shows no pachygyria or polymicrogyria. 

The most common genetic abnormality is DCX gene mutation on the long arm of chromosome X, that's why mostly females are affected.  LIS1 gene, which is a gene responsible for type 1 Lissencephaly, is affected in some cases.

Straight back syndrome

The whole spine T2 sagittal image shows straightening of the normal kyphotic angulation of the dorsal spine. Reduced antero-posterior dimension of the thorax is also noted. Features are favoring Straight Back Syndrome. (The patient had come for symptoms of low backache with radiation to right leg). 

The above image shows T2 weighted MRI of the dorsal spine. Image on the left shows a yellow line drawn along the anterior surface of D4 to D12 vertebral bodies. In straight back syndrome the distance between the yellow line and anterior surface of midportion of the D8 vertebral body should be < 1.2 cm. (This is the Davies modification (1980) of the DeLeon (1956) criteria, and is actually mentioned in the lateral chest x-ray, and not in MRI). In the above image this distance measured only ~2mm. 

The right side images shows AP dimension of thorax from the posterior surface of the sternum to the anterior surface of the D8 vertebral body, which should be < 10-11 cm. Here it measured exactly 10 cm.

Straight back syndrome is considered as a benign skeletal abnormality of the thorax, narrowed AP dimension of the thoracic cavity, resulting in cardiovascular and bronchial compression, but with most of the patients being asymptomatic. If symptomatic, patients usually present with symptoms of chest pain and palpitations, mimicking a primary cardiac condition. An ejection systolic murmur may be heard in the pulmonary area on auscultation. 

Mitral Valve prolapse (MVP) may be seen as an association in up to two third of patients. Prominence of the pulmonary arteries, deviation of the heart to left and cardiomegaly are also described in association.

References: 

1. Davies, M. K., Mackintosh, P., Cayton, R. M., Page, A. J., Shiu, M. F., & Littler, W. A. (1980). The straight back syndrome. The Quarterly journal of medicine, 49(196), 443–460.

2. Gold PM, Albright B, Anani S, Toner H. Straight Back Syndrome: positive response to spinal manipulation and adjunctive therapy - A case report. J Can Chiropr Assoc. 2013;57(2):143-149.

Solitary metastatic lesion of the spine

 70Y old female patient present with low back ache. MRI of the lumbo-sacral spine was performed. 

The whole spine T2 sagittal image is showing an isolated lesion involving the S2 vertebra and superior part of the S3. Lesion is appearing slightly hyperintense in T2, iso to slightly hypointense in T1 and markedly hyperintense in STIR. It is expansile, causing anterior and posterior contour bulge of the involved vertebrae and also the destruction of anterior cortex. 

Lesion is shown in the axial T2 and STIR coronal images here. T2 Axial images is showing near total obliteration of the the sacral spinal canal at the level, with marked compression of the remaining nerve roots. 

Moderate enhancement of the lesion is present with associated restricted diffusion. Features are in favor of an aggressive lesion. Signal intensity is not consistent with chordoma or Giant Cell Tumor.

Biopsy of the lesion was performed, was found out to be metastatic lesion from adenocarcinoma.  

Asymptomatic vascular compression of the cisternal segment of the facial nerve

 40 year of female patient presented with headache. No tinnitus / facial nerve palsy / hemi-facial spasm.

The above CISS 3D Axial image is showing significant anterior displacement of the cisternal segment of the right facial nerve (orange arrow) by the Anterior Inferior Cerebellar Artery (AICA) loop. AICA loop was seen coursing in between the cranial nerves VII and VIII. The focally thickened appearance of the right facial nerve is due to the AICA closely abutting the posterior aspect of the nerve at that site. No compression on the vestibulo-cochlear nerve was seen. 

Sagittal reformats of the CISS images, showing the contact of the AICA loop (orange arrow) and the facial nerve (yellow arrow). Green arrow points to the cranial nerve VIII. 

Interestingly the patient didn't have any symptoms related to the facial nerve compression at the time of the scan.

The Chavda classification of vascular loops in relation to the Internal Acoustic Canal (IAC) is: 

Type I   : Loop is present in the CP angle cistern, but not entering the IAC.

Type II  : Enters the IAC, but <50% of the length of IAC. 

Type III : Occupies > 50% of the IAC. 

Kinking or angulation of the nerve at the site of contact is taken as a sign of vascular compression.

Gorrie et al used a second classification system assessing the relationship of the vascular loop with the VIII cranial nerve. Four different relationships were categorized: 

Class A, no contact; 

Class B, vascular loop lying directly adjacent to nerve; 

Class C, loop running in between VII and VIII nerve ;

Class D, vascular loop displacing the nerve resulting in bowing of the nerve.

Gorrie et al. stated: 'A significant association was demonstrated between the AICA running between the vestibulocochlear and facial nerves. The p value was found to be 0.0162, which demonstrates a statistically significant association between the presence of a Class C loop and hearing loss.'

Studies are yet to conclusively show the significance of these 'compression' as even normal patients with no tinnitus / hearing loss have the type III AICA loop in the IAC.

See a case of of type II vascular loop here.

References

1. McDermott et al. (2003) McDermott AL, Dutt SN, Irving RM, Pahor AL, Chavda SV. Anterior inferior cerebellar artery syndrome: fact or fiction. Clinical Otolaryngology and Allied Sciences. 2003;28:75–80. doi: 10.1046/j.1365-2273.2003.00662.x.

2. Gorrie et al. (2010) Gorrie A, Warren 3rd FM, De la Garza AN, Shelton C, Wiggins 3rd RH. Is there a correlation between vascular loops in the cerebellopontine angle and unexplained unilateral hearing loss? Otology & Neurotology. 2010;31:48–52. doi: 10.1097/MAO.0b013e3181c0e63a.

3. Kim SH, Ju YR, Choi JE, Jung JY, Kim SY, Lee MY. Anatomical location of AICA loop in CPA as a prognostic factor for ISSNHL. PeerJ. 2019 Mar 11;7:e6582. doi: 10.7717/peerj.6582. PMID: 30881768; PMCID: PMC6417406.

Quadrigeminal cistern lipoma

70Y Female patient. Previous history of surgery for ? brain tumor (details not available).  

Sagittal T1 weighted images above are showing a T1 hyperintense lesion in the quadrigeminal cistern. Right parasagittal image is showing a convexity meningioma (green arrow). Blue arrow points to the previous occipital craniectomy defect.

T1 WI axial image shows the hyperintense lesion in the quadrigeminal plate cistern. The Susceptibility Weighted Images (SWI) showed hypointense blooming artifacts, more along the rim of the lesion. 

Lesion is appearing hyperintense in T2WI, suppressed in T2 FS FLAIR images. 

The patient also has associated absent septum pellucidum.

The right superior parietal convexity meningioma is noted with mass effect on the parietal lobe (Green arrow). Orange arrow points to the absence of septum pellucidum. 

 

Shark face !!! in MRI Prostate 😂

Image from a case of Ca prostate MRI, lower section, resembling a shark eating a fish !!. 😅🙈

Haglund Syndrome

Haglund deformity is the reactive enlargement of the posterior calcaneal tuberosity, better assessed in the sagittal images. Presence of Haglund deformity has a greater prevalence of retrocalcaneal bursitis and insertional Achilles tendinosis.

Haglund deformity doesn't always result in Haglund syndrome. 

Haglund syndrome refers to the presence of Haglund deformity, retrocalcaneal bursitis and insertional Achilles tendinosis.

These images are of a 50yr old male patient who presented with chronic heel pain history. First image shows the small abnormal prominence of the posterosuperior calcaneal tuberosity (Green arrows). 

Associated fluid in the retrocalceal bursa, insertional and non-insertional Achilles tendinosis with associated paratenonitis are also present. Edema and fluid signal in the Kager's fat pad is also present here.

Since this condition is also associated with wearing high heels in females, its sometimes referred to as 'pump-bump'.

Diffuse Idiopathic Skeletal Hyperostosis (DISH)

 

DISH or Diffuse Idiopathic Skeletal Hyperostosis, aka Forestier disease, is a common disorder of unknown etiology, characterized by intermittent pain and stiffness in the involved spine segments. Spinal involvement of DISH characteristically produces flowing type ossifications in the anterolateral margins of the at least 4 contiguous vertebrae. This ossification can be of variable thickness, can measure up to 2cm. 

The above images shows prominent ossifications in relation to the anterior aspects of C3 to C7 levels, with C4 to C7 appearing continuous. This is also causing mass effect on the hypopharyngeal soft tissue / pharyngo-esophageal junction. 

The 'Light bulb sign' of liver hemangioma [MRI]

 Light bulb sign refers to the persistent T2 bright homogeneous signal intensity of a typical liver hemangioma, on increasing the TE  (T2 weightage) of the image. The bright signal is compared to that of a glowing light bulb. This may however also be seen in hypervascular metastases. 

MRI Liver of an young patient with multiple hemangiomas in both lobes. 

On increasing the TE, the signal intensity of hemangioma is well preserved, whereas the signals of other structures such as liver and spleen gets reduced.  

Hemangiomas are T2 homogenously hyperintense, with well defined margins with or without small lobulatations. They appear hypointense in T1WI, hyperintense in DWI. In post Gadolinium images they show peripheral nodular intense enhancement in the arterial phase, with gradual centripetal filling-in of the contrast. In the delayed hepatobiliary phase hemangiomas appear hypointense as they do not contain any hepatocytes. 

Isolated Area Postrema Syndrome (APS) presenting as intractable nausea and vomiting (NMOSD)

 Area Postrema (AP) is an emetic reflex center, one of the circum-ventricular organs that is outside the blood-brain barrier(BBB). It is located in the dorsal aspect of the medulla, at the caudal end of the fourth ventricle. AP along with Nucleus Tractus Solitarius (NTS) and dorsal motor nucleus of Vagus forms the dorsal vagal complex, where most of the vagal afferents terminate. AP by its location outside the BBB is exposed to the toxins in the blood. Activation of the AP brings nausea and vomiting, due to its projections into the NTS. 

AP through its hypothalamic,brainstem connections also regulate fluid balance, immunomodulation etc. It also chemo-sensitive neurons regulating hiccups. 

Neuro Myelitis Optic Spectrum of Disorders (NMOSD) are a group of autoimmune inflammatory demyelinating diseases of the CNS. Most of these show characteristic antibody to aquaporin-4 (AQP-4) water channel. 

 Attacks of intractable nausea, vomiting or hiccups (INVH) in the presence of a dorsal medullary lesion is called as the Area Postrema Syndrome (APS) and upto 30% of NMOSD patients will have APS during their disease course. 

NMOSD lesions in the Area Postrema shows loss of AQP-4 immunoreactivity and inflammation and characteristically lacks necrosis and demyelination which is seen in spinal cord and optic lesions, explaining reversibility of the symptoms. Patients have to tested for Serum and CSF AQP4-IgG antibodies. 

Isolated APS is easily mistaken clinically and is often attributed initially to other causes like gastritis including H.Pylori, GERD, Cholecystitis, Pancreatitis, food poisoning, gastroparesis etc. 

Immunotherapy usually results in rapid relief of symptoms usually within 2-3 days, responding to Methyl Prednisolone or Immunotherapy in most cases. Refractory cases may need drugs like Azathioprine, MMF, Rituximab.   

Below are the MRI images of a young female with intractable nausea and vomiting. 

T2 and T2 FLAIR hyperintensity noted in the region of the Area Postrema, called the Inverted-V sign.

Bilateral symmetrical normal optic nerves.

No restricted diffusion seen in the abnormal signal areas of Area Postrema.

Corresponding sagittal T2 FLAIR image showing the level of Area Postrema.
Abnormal signal intensity is also seen in the inferior colliculi of midbrain in the sagittal image. 

Diagram showing the location of AP, NTS in the dorsal medulla.