The three axial oblique images in this 43-year-old with hip pain demonstrate an abnormality. What are the associated potential imaging findings that might accompany this abnormality?
Axial oblique fat-suppressed GRE
The lack of tapering of the femur head to the neck is known as asphericity. This lack of tapering is associated with a bump in the anterior aspect of the femoral head neck junction. The bump is also associated with a friction-related pseudocyst (“herniation pit”) that occurs when the hip is in flexion and especially in flexion-internal rotation as this area rubs across the acetabulum. Sometimes the friction produces edema but not an actual cyst.
- In such a patient, the alpha angle (if measured) would be elevated.
- An abrasion, ulcer or erosion would often be seen in the far anterior superior acetabulum as this bump rides against and abrades or erodes the cartilage of the acetabular roof.
- Some patients with this abnormality may have a shallow acetabular cup.
- Labral tears and detachments are frequent.
- Capsular rents or tears may occur.
Clinically, such patients often experience pain in hip flexion worse in internal more than external rotation. This case illustrates an axial oblique head neck junction shape of Cam or Type 1 hip impingement syndrome. For more case review, check out MRI Online.
You are shown two raw data images from an MRA/MRV and a sagittal thin-section T2 image. What is the diagnosis (arrows), what is the most likely blood supply, and which vein is persistently dilated as a result of this entity?
The findings are consistent with a vein of Galen (arrow) malformation (VOGM). The feeders are usually via posterior choroidal feeders and thalamoperforates with rapid drainage into a dilated median prosencephalic vein which normally involutes. Often, the posterior communicating artery and posterior cerebral arteries are dilated (not shown). Vein of Galen arteriovenous malformations of the medial prosencephalic system account for 30 percent of cerebral malformations in the pediatric age group. It is the most common intrauterine diagnosed intracranial vascular malformation.
Neonatal presentation is usually the choroidal type with high output cardiac failure and an intracranial bruit. The infant type is more mural and may present with hydrocephalus due to venous hypertension or aqueductal stenosis. Delayed presentations in childhood include developmental delay and hydrocephalus, usually in the mural type. The cerebral arteriovenous fistula of the median prosencephalic vein (MPV) occurs at 6-11 weeks gestation. The MPV fails to regress and becomes aneurysmal and drains via the straight sinus or persistent falcine sinus and the vein of Galen does not actually form. The straight sinus is present only 50 percent of the time. Note that the vein of Galen may dilate secondary to high-flow parenchymal AVM (Yasargil 4).
Vein of Galen aneurysms are often classified via the Yasargil system:
- Type 1: small pure cisternal fistula between the vein of Galen and either pericallosal arteries (anterior or posterior) or posterior cerebral artery.
- Type 2: Multiple fistulous communications between the vein of Galen and the thalamoperforating vessels.
- Type 3: High-flow mixed type 1 and type 2. Flow voids are apparent.
- Type 4: Parenchymal arteriovenous malformation (AVM) with drainage into the vein of Galen.
For more neuro case review, check out MRI Online.
This 15-year-old has knee pain months after a collision injury. What do the arrows identify on the axial MRIs through the patella? Is it surgical? What are some options for treatment?
The arrows point to large flaps and fragments of cartilage. These have resulted from a chronic osteochondral fracture that includes a defect extending through the patellar subchondral plate (four small arrows, image two). Because of the size of the fragments and the likelihood they would further break off and contribute to a locked knee, they are surgical.
Surgical options include debridement, osteochondral autologous transplant (OAT) procedure and in vitro cartilage cell harvesting with grafting of the defect. A less accepted and more controversial choice would be some form of stem cell/platelet rich plasma “cocktail”. For more case review, check out MRI Online.
This 39-year-old presents with chronic knee pain. Is his ACL torn? How do the findings in this case relate to the movie “A River Runs Through It”, starring Brad Pitt? You are shown a sagittal PD SPIR (image 1), sagittal T1 (image 2), and a coronal PD SPIR (image 3).
Answer: Be sure to take note of the arrow in each image. If you look carefully, you can see fibers of the ACL (that are straight, arrows in image 1 and 2) running through a morass of inflammatory tissue, thus the analogy to “A River Runs Through It”. This is perhaps best appreciated on the coronal image (image 3, arrow).
Still, a pseudomass is created. In case you were wondering what causes this swelling, there are several different etiologies. It can occur as a result of a prior single trauma. It can occur due to repetitive microinstability. Finally, it can occur as a manifestation of trochlear notch dysplasia where the notch is too narrow from side to side or too short from top to bottom, as is the case here.
You will hear a number of descriptors and signs for this phenomenon including notch synovitis, ACL swelling, mucoid degeneration and ganglion pseudocyst formation. This reader only uses the term mucoid degeneration or ganglion pseudocyst formation when there is a well-defined area of smooth T2 hyperintensity with mass effect. Check out this similar case in a 35-year-old female. For more knee case review, check out MRI Online.
This 35-year-old woman presents with pain and locking when bending joint in her right knee. She has no recent injury and no history of surgery to this knee. She has patellofemoral maltracking, but what is the most important finding?
Sagittal T2 fat-suppression
Coronal T2 fat-suppression
Sagittal PD (SPIR)
Answer: The most important finding is the septated cystic structure involving the upper fibers of the anterior cruciate ligament. This is consistent with cystic mucoid degeneration with ganglion pseudocyst of the cruciate (arrows). Any combination of prior injury, microinstability and/or a small femoral notch (notch dysplasia or stenosis) can produce this finding. For more knee case review, visit MRI Online.
This fetus has a rare diagnosis. What is the diagnosis, and why is the movie “Splash” with Tom Hanks and Daryl Hannah a tip-off?
The answer is sirenomelia, which is also known as Mermaid syndrome. In this particular case, the infant was stillborn with complete fusion of the legs. The leg fusion gives the appearance of a mermaid’s tail. The condition is seen in 1:100,000 live births; about as rare as conjoined twins. The patients usually have kidney and bladder dysfunction and more than half the cases are stillborn. The condition is 100 times more likely to occur in identical twins than in single births. Failure of the normal vascular supply from the lower aorta in utero is the suggested cause. For more case review, check out MRI Online.
This 10-year-old female has a history of systemic lupus erythematosus and has suddenly developed right-side blindness. She is dealing with an undiagnosed clinical syndrome, as well as a complication. Identifying both the underlying syndrome and its complication will be critical to the treatment plan.
Answer: She is dealing with an intracranial hemorrhage as a complication of posterior reversible encephalopathy syndrome (PRES). Always consider an underlying disease in young stroke patients, including brain tumor with intra-tumoral bleeding, vascular malformation, venous thrombosis, vascular dissection or septic emboli, etc. The presence of characteristic FLAIR/DWI hyperintensities in bilateral parieto-occipital cortex suggests PRES. However, in classic PRES the DWI is normal, near normal or has less parenchymal volumetric involvement than seen on FLAIR. PRES is due to loss of vascular autoregulatory function and is associated with hypertension and conditions linked to hypertension. Some drugs are linked to PRES, the classic being cyclosporine.
Note: This case was shared by Dr. Chih-Chun Wu, who was recently selected as a scholarship winner for ProScan’s NYC Neuro Case Review. Congratulations to Dr. Wu.
This three-year-old female with multiple congenital hairy nevi syndrome presents with speech difficulty and right hemiparesis. Which rare congenital disorder does she have, and what more common findings is this condition known to mimic? The first image shown is an axial T1 post-contrast with ill-defined meningeal enhancement (pink arrow), while images two and three are axial T1 pre- and post-contrast images from a few months later showing a mass (blue arrow). The fourth image is a sagittal T1 post-contrast with intrathecal enhancement (yellow arrows).
The answer is neurocutaneous melanosis. It is a rare congenital disorder causing dysplasia of neuroectodermal melanocyte precursor cells, which causes proliferation of melanin producing cells in the skin and leptomeninges. Benign overgrowth of melanocytic cells or development of malignant melanoma is often the cause of the death.
Differentials for the leptomeningeal melanocytosis and enhancement include subarachnoid hemorrhage on a non-contrast CT, or enhancing meningitis (malignant or infectious). Differentials for the melanocytic mass can include a meningioma, dermoid, or focal hemorrhage. Although rare, neurocutaneous melanosis should be considered when there is diffuse leptomeningeal enhancement with a rapidly-growing extra-axial mass.
Note: This case was shared by Dr. Neha Gowali, who was recently selected as a scholarship winner for ProScan’s NYC Neuro Case Review. Congratulations to Dr. Gowali.
This 55-year-old male has right knee pain after a fall down an embankment. He has an ACL tear, but what other injuries are present in this complex case? What is indicated by the arrows? You are shown these five static images, plus a GIF rotating a sagittal series.
This patient has an ACL tear (pink arrows) with pivot shift osseous edema, joint effusion and posterior capsular disruption. Other items to note:
- Complex tear of the medial meniscus with fragment displaced into the posterior intercondylar notch (images 4 and 5, arrows).
- Posterior central or deep lateral meniscus capsular attachment tear, with mostly vertical Wrisberg rent or rip tear (image 3, arrow). The meniscopopliteal fascicles are also injured laterally (blue arrows).
- Posterolateral corner injury with arcuate sprain (orange arrows) or tear, plus stretch injury of the popliteal fibular ligament (yellow arrow).
- Disrupted posterior ligament of the knee injury (image 1, arrow).
- Longitudinal interstitial split tear of the fibular collateral ligament.
- Patellofemoral chondromalacia.
For more knee case review, visit MRI Online.