Perthe's Lesion

MR Arthrogram:  Avulsed anterosuperior cartilagenous labrum with periosteal stalk still attached to glenoid

A variation of the Bankart lesion, the Perthes lesion occurs when the scapular periosteum remains intact but is stripped medially, and the anterior labrum is avulsed

from the glenoid but remains partially attached to the scapula by the intact periosteum. Sometimes the laburm settles into its normal position but is detached and unstable.  This type of Perthes lesion may be difficult to diagnose.  This example is displaced and easier to identify.

Traumatic Aortic Tear

CTA chest: Aortic tear at ligamentum arteriosum level with extensive RT hemothorax

Up to 15% of all deaths following motor vehicle collisions are due to injury to the thoracic aorta.  The proximal descending aorta, where the relatively mobile aortic arch can move against the fixed descending aorta at theligamentum arteriousm, is at greatest risk from the shearing forces of sudden deceleration.Chest X-ray is still used as the primary screening study, but has a low sensitivity. The sensitivity of modern CT scanners is reported at 97-100%, with a negative predictive value of 100% and specificity of 83-99%. Many surgeons  rely solely on the CT scan to plan operative or endovascular repair. Endovascular repair of thoracic aortic injury is available.

Reference: trauma.org 9:4, April 2004 Chest Trauma: Traumatic Aortic Injury

Ulcerative Colitis

Fig 1. coronal CT abdomen and pelvis. Mildly distended colon with loss of haustral markings.






Fig 2. Coronal 3d. featureless, lead pipe colon

Ulcerative colitis is a type of inflammatory bowel disease. It involves the large intestine with characteristic ulcers. Symptoms include bleeding and diarrhea. Like Crohns, Ulcerative colitis is an intermittent disease, with periods of active disease and periods that are asymptomatic.

Ulcerative colitis occurs in less than 0.1% of the population. The disease is more prevalent in northern countries. Ulcerative colitis has no definIte cause. These appears to be a genetic component. Treatment is with anti-inflammatory drugs, immunosuppression, and biological therapy targeting specific components of the immune response. Colectomy (partial or total removal of the large bowel through surgery) is occasionally necessary, and is considered to be a cure for the disease.

In patients with long standing disease, a lead-pipe colon can develop. There is hypertrophy of the muscularis mucosa. The thickened muscle layer gives the colon a narrowed ahaustral form. Strictures may also narrow the lumen.


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Caput Medusae

VR image of abdominal wall in a patient with cirrhosis and portal venous hypertension.  Inset is Head of Medusa from God of War II (Sony)

Distended and engorged paraumbilical veins, radiating from the umbilicus across the abdomen to join systemic veins. The name caput medusae (Latin for "head of Medusa") originates from the apparent similarity to Medusa's hair once Athena had turned it into snakes. It is a sign of severe portal hypertension that has decompressed by portal-systemic shunting through the paraumbilical veins. DDX would include IVC obstruction which can also produce abdominal wall collateral veins.

Sorry it has ben a while since last post .

Struma Ovarii

Ultrasound shows a large complex solid and cystic mass  in the RT ovary, which was a mature teratoma.  Pathology shows follicular glands filled with colloid interspersed throughout the tumor

Struma ovarii is a rare ovarian tumor defined by the presence of thyroid tissue comprising more than 50% of the overall mass, usually as part of a teratoma, but sometimes as part of a serous or mucinous cystadenoma. They make up approximately 1% of ovarian tumors. They are benign about 2/3 ‘s of the time. Thyrotoxicosis is seen in 5%. Surgical resection is the treatment.


Yoo SC, Chang KH, Lyu MO, Chang SJ, Ryu HS, Kim HS. Clinical characteristics of struma ovarii. J Gynecol Oncol. Jun 2008;19(2):135-8.

Gunshot Wound to Brain

CT brain shows a bullet wound with entry at the RT frontal lode and exit at the LT frontal lobe.  The wound cavity is filled with blood.  The inset shows a ballistic cavity from a bullet in a gelatin block.

When a bullet strikes a person, tissue is crushed. The bullet's forward movement creates a temporary tunnel that expands to a larger tunnel. The larger tunnel is considered to be a temporary "cavitation" wave. Tissues in the temporary cavity sustain damage from compression, deformation and shear. After a bullet passes through, the temporary cavity recoils , but with a remaining cavity, called the permanent cavity. Tissue of the permanent cavity may be damaged and nonviable. Secondary missiles, such as bullet and bone fragments, can result in additional damage

The wound is created by the physical damage of the bullet itself and cavitation. Cavitation is the formation of vapor bubbles in a flowing liquid in a region where the pressure of the liquid falls below its vapor pressure. Inertial cavitation is the process where a bubble in a liquid rapidly collapses (bursts), producing a shock wave. A shock wave is a wave that carries energy and can propagate through a medium. Shock waves are characterized by an abrupt, nearly discontinuous change in the characteristics of the medium with an extremely rapid rise in pressure, temperature and density.

Gastrointestinal Stromal Tumor

One of the most common mesenchymal tumors of the GI tract.  Patients may present with early satiety, gastrointestinal bleeding, vague abdominal pain. Actual obstruction is rare.  The tumor can be large by time the diagnosis is made and patients may present with metastases (usually liver). On imaging studies GISTs appear as intramural masses.
Internal calcifications may be present. As the tumor grows larger it can undergo necrosis and ulcerate. GISTs can directly invade adjacent structures in the abdomen. Mets are ususlly to the liver. Spread to the peritoneal cavity can be seen.Metastatic adenopathy  is uncommon. 70% of GISTs occur in the stomach, 20% in the small intestine and less than 10% in the esophagus. GISTs are  connective tissue tumors. They are thought to arise from interstitial cells of Cajal (part of the autonomic nervous system of the intestinethat control motility.)


Most GISTs arise from a mutation in the c-kit gene.  This gene encodes for a transmembrane growth factor receptor called stem cell factor (scf), a tryosine kinase receptor. Mutations to c-kit usually occur in the intracellular domain of the receptor and cause it to be active independent of scf binding. GISTs that do not have a c-kit mutation often have a mutatuion in a related tyrosine kinase receptor, platelet derived growth factor receptor alpha (PDGFR-a).

GIST tumors with c-kit or PDGFR-a mutations can be treated with Imatinib (GLEEVAC), a tyrosine kinase inhibitor.

Miettinen M, Lasota J. "Gastrointestinal stromal tumors: review on morphology, molecular pathology, prognosis, and differential diagnosis". Arch. Pathol. Lab. Med. 130 (10): 1466–78

Multiple Myeloma

select image for larger view

Radiographs of the left knee show a poorly marginated lytic bone lesion in the distal femur.  The patient eventually had a pathologic fracture throught that lesion (also shown). Lytic thoracic spine lesions were also doccumented by CT.  Peripheral blood smear was loaded with plasma cells.  These cells stain positive for CD 138 (inset).  SPEP revealed an IgG Kappa spike. Findings are consistant with multiple myeloma. 

CD 138, Syndecan 1,  is a protein which in humans is encoded by the SDC1 gene. Syndecans mediate cell binding, cell signaling, and cytoskeletal organization.  Syndecans are single transmembrane domain proteins that are thought to act as coreceptors, especially for G protein-coupled receptors. These core proteins carry three to five heparan sulfate and chondroitin sulfate chains which allow for interaction with a large variety of ligands including fibroblast growth factors, vascular endothelial growth factor, transforming growth factor-beta, fibronectin and antithrombin-1.  Altered syndecan-1 expression has been detected in several different tumor types. It is a useful marker for plasma cells

O'Connell FP, Pinkus JL, Pinkus GS . "CD138 (syndecan-1), a plasma cell marker immunohistochemical profile in hematopoietic and nonhematopoietic neoplasms". Am. J. Clin. Pathol. 121 (2): 254–63

Squamous cell carcinoma of the bladder

Click on image for large view

The majority of bladder cancers are transitional cell cancers.  Squamous cell carcinoma of the bladder (red and white arrows) is less common in North America.  It is often secondary to shistosomal infection (schistosoma haematobium).  It  may be associated with other types of long term irritations: chronic infections, calculi, treatment with cyclophosphamid. It occurs most often in the seventh decade with a slight male predominance. It most commonly involve the trigone and lateral walls. This patient had a long term indwelling suprapubic tube (white arrow head)  Distant metastases are infrequent (8-10%).  The prognosis is poor .Most patients die from failure of local control of the tumor.  Foci of central keratinization (keratin pearls) are seen within concentric layers of the abnormal squamous cells, occurring in the squamous cell carcinoma on the micro view (yellow arrow).

Genetics of SCCA of the bladder is complex. Chromosome 9 monosomy is an early event and might even occur in preneoplastic stages. Loss of homozygosity  is  found in particular in the locus where CDKN2/P16 sits. CDKN2/P16 is a tumor suppressor gene on chromasome 9p21. 

Loss of homozgosity is an important concept in cancer biology.  Mutant tumor suppressors genes are usually recessive (mutant oncogene are typically dominant).  Loss by deletion of the non mutant member of a homozygous  gene pair allows the mutant recessive gene to be expressed. Products of the mutant tumor supressor gene are non or less functional.  This is the TWO HIT (Knudson-Nordling) Hypothesis of cancer mutation.  One hit mutates a member of the homozygous tumor suppressor pair, the second deletes the gene that has not experienced a mutation.

References

Squamous cell carcinoma of the bladder: pathology, diagnosis and treatment.
Shokeir AA. BJU Int. 2004 Jan;93(2):216-20

A survey of homozygous deletions in human cancer genomes,. Charles Cox, Graham Bignell, Chris Greenman, Arne Stabenau, William Warren, Philip Stephens, Helen Davies, Stephen Watt, Jon Teague, Sara Edkins, Ewan Birney, Douglas F. Easton, Richard Wooster, P. Andrew Futreal, and Michael R. Stratton. PNAS March 22, 2005 vol. 102 no. 12 4542-4547

UPDATE:  I have it on reasonably good authority that our NUC MED department will be moved into a new area within the main department of radiology and that a GE Hawkeye SPECT/CT scanner will be installed in the new area.  To my knowledge this will be the first dedicated SPECT/CT in the region. This allows easy image registraton between SPECT and CT images and has applications in Oncology, Orthopedic, Neuro and Infectious Disease imaging.

Thoracic Aortic Pseudoaneurysms

Axial, Sagital and VR images. Post contrast CT Aorta. 

This patient had recent cardiac valve replacement at another hospital and presented to the ED with increasing chest pain.  There are 2 small pseudoaneurysms in the anterior ascending aorta possibly at the sites of prior canulation for cardiac bypass (red arrows).  There is hematoma in the anterior mediastinum (white arrow).

Update

Interview season for the residency program has ended.  Thank you to all of the candidates who came to Toledo for interviews. We had many excellent candidates this year and we now have to get to the business of ranking, which is always difficult. 

We are in the process of finishing a PACS upgrade and are in the final stages of a RIS upgrade.  This should really streamline workflow.

Renal Cell Carcinoma Invading Renal Vein and IVC (No not a PET/CT)

Select Image to Enlarge

Diffusion weighted coronal image and fused DWI and Axial T2w images show a large mass with restricted diffusion in the upper pole of the right kidney consistent with renal cell carcinoma invading the renal vein and the inferior vena cava.

Diffusion imaging offers an adjunct to traditional post contrast MRI.  High cellular density and abundant macromolecules in the cytosol cause the speed of diffusion of H2O in malignant tissues to slow.  This restriction of diffusion can be measured with MRI.