Inverted Napoleon Hat Sign

Radiograph of LS Spine shows abnormal contour of the L5 vertebra.

Close-up view of the same.

Inverted magnified image of L5 showing the hat like contour of L5 vertebra.

Picture of Napoleon wearing his hat in the inset. Right side image is inverted to show the hat like appearance of L5 vertebra more clearly.

The reason for this is due to spondylolysis of L5 (defects in pars interarticularis) and signficant anterolisthesis (here grade II) over S1 vertebra, which is showing in this lateral radiograph.

Supracondylar humeral fracture

Blue arrows point to the elevated / displaced anterior and posterior fat pads. Orange arrows point to the fracture.

Venous Intravasation during HSG

Venous intravasation when using water soluble contrast media, is considered an innocuous finding. May be seen up to 6% of cases, sometimes even in healthy patients. Common causes include recent uterine surgery, tubal block and excessive injection pressures.

REFERENCE:
Ubeda B, Paraira M, Alert E, Abuin RA. Hysterosalpingography: spectrum of normal variants and nonpathologic findings. AJR Am J Roentgenol. 2001 Jul;177(1):131-5.

Parieto-occipital encephalomalacia in a child

 12yr old with repeated seizures.

Bilateral parietal and occipital gliotic-encephalomalacic changes are noted, almost in a symmetrical manner.

Cavernous Sinus Dermoid Cyst

Clinical History : 60yr old female patient with right 3rd nerve palsy. Suspecting a PCom aneurysm, CT angiogram was performed which showed no intracranial aneurysms.

However a heterogenously hypodense non-enhancing lesion was seen in the right cavernous sinus, with cavernous ICA seen medially displaced. Lesion anteriorly showed markedly hypodense area of negative attenuation varying from -100 to -150HU, suggesting intralesional fat. Posterior rim of the lesion showed small calcfications. Lateral hyperdense rim was thought to represent the thickened dural layer of cavernous sinus.

Nasu Hakola disease

• Rare hereditary Autosomal Recessive disorder.
• Also known as Polycystic Lipomembranous Osteopathy with Sclerosing Leukoencephalopathy (PLOSL). 
• Progressive presenile dementia, with associated recurrent bone fractures, due to cystic lesion of long bones. 
• Progresses in  4 stages: Latent, Osseous, Early neurologic and late neurologic. The disease may not be recognized until the neurologic symptoms start in the third or fourth decade, characterized mainly by frontal lobe symptoms of loss of concentration, loss of social inhibition, loss of judgement etc.
• Radiologically white matter hyperintensities of brain, neuroparenchymal atrophy, basal ganglia calcifications, especially putaminal etc are noted. Caudate head atrophy with widening of frontal horns as in Huntingtons disease may be seen, with increased intercaudate distance to inner table width ratio.
• No treatment is available at present and death usually occurs by 5th decade.

Acute PCA territory infarct

Right occipital lobe and thalamic involvement.

Right posteromedial temporal lobe infarct.

Absent flow in right PCA (P2) (Black arrow) in TOF MRA MIP images. White arrow pointing to left PCA P2 segment.

The major PCA segments are the Pre-communicating / Peduncular / P1 segment, Ambient / P2 segment and the Quadrigeminal / P3 segment.

The major branches from P1 segment include Posterior thalamo-perforating arteries and the median posterior choroidal artery.

Major branches from P2 segment of PCA includes lateral posterior choroidal artery and posterior choroidal artery.

Inferior temporal arteries, parieto-occipital artery, calcarine artery, posterior pericallosal (splenial) arteries are the major branches of the P3 or quadrigeminal segment of PCA.



Reference : Diagnostic Neuroradiology, Anne.G.Osborn, 1994.

Solid Pseudopapillary Tumor of Pancreas

Solid Pseudopapillary Tumor (SPT) is a rare, benign, exocrine pancreatic tumor. It is seen in African or Asian females in 2nd or 3rd decade usually. These tumors can be asymptomatic or may present with a gradually enlarging painless mass in abdomen (as in this case), or with vague abdominal pain or discomfort.

SPTs are well encapsulated lesions with varying degrees of hemorrhage, necrosis and cystic degeneration which make them heterogeneous in both plain CT and post contrast images, with hemorrhage and capsule being the most important distinguishing features from other pancreatic neoplasms. 

The larger lesions have peripheral solid areas and central necrotic / cystic areas. The smaller or early lesions can be entirely solid, and can be difficult to differentiate from islet cell tumors. Some even can have internal septations in the cystic areas adding to the confusion.

SPTs are usually benign, but occasionally can rarely have local aggressive features, capsular invasion, metastasis(liver), lymphadenopathy. These aggressive tumors are more seen in older patients with a male gender predilection. Benign SPTs are usually completely cured by surgery. Long term survival is better with surgical treatment even in the presence of liver metastasis.¹

The following case is a 25yr, female with complaints of feeling of mass in abdomen.

Above CT topogram shows a soft tissue density mass lesion in the left upper quadrant, with compression on stomach and displacing the distal transverse colon and splenic flexure inferiorly. No obvious calcifications detected. No rib erosions / lysis / widening seen. DDs would include Renal, Pancreatic, Adrenal, Gastric lesions. If age is given, possibility of SPT of pancreas should be higher in the list of DDs. This can be a good opening image for FRCR 2B viva discussion.

 

Plain CT images show heterogenous lesion involving tail of pancreas, showing attenuation values ranging from 15-25HU in hypodense areas and rest showing mostly 40-45HU. No obvious hemorrhagic density was seen. Small areas of capsular calcfications were noted in the posterior aspect mainly.

The classic 'Claw Sign' in Radiology.

Post contrast images showing gradually increasing enhancement in few peripheral areas in the lesion. The hypodense areas in plain study showed no significant enhancement.

Lesion was showing well defined margins, with mass effect on adjacent structures and without any evidence of perilesional infiltration.This was reported as SPT.  Patient underwent splenectomy and distal pancreatectomy. Pathology report came as SPT.





References:
1: Solid-pseudopapillary tumor of the pancreas: a surgical enigma?
Martin RC, Klimstra DS, Brennan MF, Conlon KC.
Ann Surg Oncol. 2002 Jan-Feb;9(1):35-40. PubMed PMID: 11833495.

2: Solid Pseudopapillary Tumor of the Pancreas: Typical and Atypical Manifestations.
Jin-Young Choi, Myeong-Jin Kim, Joo Hee Kim, Seung Hyoung Kim, Joon Sok Lim, Young Taik
Oh, Jae-Joon Chung, Hyung Sik Yoo, Jong Tae Lee, and Ki Whang Kim.
American Journal of Roentgenology 2006 187:2, W178-W186.

3: Solid-Pseudopapillary Tumor of the Pancreas.
Kristin M. Coleman, Michael C. Doherty, and Steven A. Bigler.
RadioGraphics 2003 23:6, 1644-1648.

4. CT and MRI of the Whole Body, John.R.Haaga, 6th Edition.

What's your diagnosis? : Case 4 [June 25th, 2017]

25y female, feeling of mass in abdomen.

Post your answers as comment. Case answer and discussion will be posted in few days.

Click here for the ANSWER.

What's your diagnosis? : Case 3 [June 25th, 2017]

Post your answers as comment below. Answer and brief discussion will be posted in few days.

RARE : Extreme case of bilateral massive renal replacement lipomatosis

Renal Replacement Lipomatosis (RRL) a.k.a Replacement fibrolipomatosis, an extremely rare condition, considered as an advanced form of renal sinus lipomatosis.The latter one is a milder form of the spectrum where the normally present renal sinus fat becomes prominent with ageing, obesity or exogenous steroids. Then again, how extreme can it go?

Renal Replacement Lipomatosis (RRL) is usually associated with infection, long term hydronephrosis, calculi and severe renal parenchymal atrophy. Renal calculous disease along with inflammatory changes are present in ~70% of the cases, and these produced symptoms of flank pain and fever.

The patient is a 60 yr old female patient with non-specific abdominal symptoms.

The above image is the non-contrast (plain) CT images which shows diffuse heterogeneous fatty tissue, filling almost the entire abdomen. On further inspection, we can see the fatty tissue is replacing the normal renal parenchyma (orange arrows), and are displacing the retroperitoneal structures like pancreas and duodenum anteriorly. Both kidneys are markedly enlarged, with near complete fatty replacement of the left kidney. Right kidney shows residual parenchyma (green arrow) in lower pole and in the interpolar region (mid-third). A few discrete fatty lesions (blue arrow) are also seen in the residual right renal parenchyma.

Above image shows the mass effect of the enlarged kidneys.

MIP (31mm) image on left shows the bilateral inferiorly oriented renal arteries, residual enhancing parenchyma of right kidney with fatty lesions. On the right, the axial post contrast images show the marked anterior displacement of the ascending colon (blue arrow) and descending colon (orange arrow).

3D VRT right lateral, frontal and left lateral views again shows the mass effect on colon which are seen markedly displaced anteriorly, against the anterior abdominal wall. Contrast filled small bowel loops are seen in RIF region.

3D VRT image showing the orientation of bilateral main renal arteries.

Delayed MIP images showing contrast excretion into the pelvicalyceal system of both kidneys. Right proximal ureter is marked by the orange arrow.

Delayed MIP axial and coronal images showing the right proximal ureter (orange arrow) and green arrows point to the opacification of pelvicalyceal system. No significant delay in contrast excretion was noted in this patient.

3D VRT of delayed excretory phase showing contrast within the pelvicalyceal system of both kidneys.

As expected renal veins showed moderate dilatation, with left renal vein measuring up to 17mm in diameter.





REFERENCES :

Indian J Nephrol. 2010 Apr; 20(2): 92–93. doi:  10.4103/0971-4065.65303, PMCID: PMC2931141, Renal replacement lipomatosis: A rare type of renal pseudotumor, N. A. Choh, M Jehangir, and S. A. Choh. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2931141/

Setty N, Uma K, Narvekar V N, Desai R S. Bilateral idiopathic replacement lipomatosis of the kidney with posterior mediastinal lipomatosis. Indian J Radiol Imaging [serial online] 2002 [cited 2017 Jun 21];12:251-2. Available from: http://www.ijri.org/text.asp?2002/12/2/251/28457

Acute intracranial hemorrhage with blood-fluid level

Blood-fluid level or hematocrit level or 'Sedimentation level' in spontaneous parenchymal hemorrhage could be due to coagulopathy or when the patient is on anti-coagulation medications. It can also be seen less often in cases of AVM or tumoral bleed (both primary and metastatic), Amyloid Angiopathy and sometimes in Radiation Induced Necrosis.


Approximately 60% of patients with increased PT/APTT can have blood-fluid levels in intracranial hemorrhages as per the reference below. 'Fluid-blood levels in acute intracerebral hemorrhage are moderately sensitive to the presence of coagulopathy (ie, abnormal prothrombin time and partial thromboplastin time) and highly specific for this condition. Thus, an intracerebral hemorrhage with a fluid-blood level should prompt a thorough search for coagulopathy because early treatment of this condition may improve the 40% mortality in these patients'.

AJNR Am J Neuroradiol. 1994 Feb;15(2):217-23.
Sensitivity and specificity of fluid-blood levels for coagulopathy in acute intracerebral hematomas.

What's your diagnosis? CASE 2 [June 20th, 2017]

Find your answer : HERE

Developmental Venous Anomaly with Cavernoma

Lateral Medullary Syndrome MRI

FRCR 2B Rapid Reporting : CXR cases

The rapid reporting cases when we sometimes miss the finding include:

• Subtle pneumothorax (especially Apical and Supine PT).
• Apical pulmonary nodule / mass.
• Lytic lesion rib.
• Mastectomy.

Other less subtle ones include : Rib fracture, distal clavicular fracture, Left Upper Lobe collapse, Right middle lobe pneumonia, RLL/LLL collapse.

Patterns of pulmonary edema, SPN, Hilar lymphadenopathy, lobar consolidation are usually the obvious 'abnormal's in the exam, which should not pose any problems.

Ill-defined air-space opacification in right mid-zone, with poor definition of right cardiac margin (loss of silhouette), consistent with a right middle lobe pneumonia.  Unless careful, can pass this as normal. 

Case courtesy of Dr Jan Frank Gerstenmaier, Radiopaedia.org. From the case rID: 25805

The above case is a case of D10 ivory vertebra due to sclerotic metastasis from breast Ca.
However for the RR purpose, see the left mastectomy, with increased transradiancy of left hemithorax.
In addition there are few surgical clips seen in the lateral chest wall on left side.

The above image shows how to follow a checklist in each CXR case. The importance to follow a checklist for each region cannot be discounted in any case. This image also shows how subtle rib lytic lesions can be.

Click here for the Chest Radiograph RR Checklist

Good web resources for RR:

1. Radiology Masterclass

2. Radiopaedia ( Now have 6 packets of RR free).

3. Norwich Image Interpretation Course.

4. FRCR Academy (Paid Membership, ~30 RR packets).

5. Dr. Sameer Shamshuddin's Website : This site has numerous other resources and links for FRCR.
6. Dr. Gaurav Shankar's FRCR 2B Tips.

Xanthogranulomatous Cholecystitis (Histology from Imaging)

Male patient, 65 years, presenting with vague right hypochondrial pain. On USG showing marked diffuse thickening of gall bladder wall, measuring up to 20mm maximum thickness. Increased vascularity is also noted within the thickened GB wall.

GB lumen showed a large 20.5mm x 18.6mm calculus, with associated luminal sludge.

Above image showing marked thickening of GB wall on left and ill-defined interface of thickened GB wall with hepatic parenchyma (segment V).

A radiologist in his / her report if can suggest the histopathological diagnosis, I believe that would be an ideal situation. Its never easy even with history, clinical diagnosis, lab tests. The ill-defined margins of thickened GB wall and hepatic parenchyma, was suspicious of infiltration. CA-19-9 value was not available at the time of scan. CECT Abdomen was also performed without much significant added information. There were no significant lymphadenopathy / other focal liver lesions / ascites. Close differentials of XGC and Ca.GB were given. Patient underwent surgery, in which GB wall seen adherent to liver and a partial resection of involved parenchyma was also done. HPR came as Xanthogranulomatous Cholecystitis.

'Hummingbird and Morning Glory' of Radiology

Progressive Supranuclear Palsy (PSP) (Syn : Steele-Richardson-Olszewski Syndrome)

• Adult onset neurodegenerative disorder. Taupathy.
• Characterized by early postural instability leading to backward falls within the first year, abnormal eye movements due to supranuclear vertical gaze palsy and abnormal cognition.
• Important to distinguish PSP from Parkinsons Disease and and others like MSA as levodopa is less or no efficacious in treatment in PSP.
• PSP shows marked dorsal midbrain atrophy, with reduction in AP diameter.
• MRI describes few signs in Progressive Supranuclear Palsy namely the Hummingbird sign (aka Penguin Sign), Morning Glory Sign. 
• Reduction in the ratio of areas of Midbrain and Pons is described in PSP.
• Other signs include widening of the Inter Peduncular Cistern and Reduced AP distance of the midbrain at the level of superior colliculus from the interpeduncular fossa to the intercollicular groove (<12mm).
• Increased T2 signal of midbrain and olives, atrophy  and increased signal intensity of superior cerebellar peduncles are also seen.
• Bilateral putamina can show hypointense signal intensity due to increased iron content.
• Associated frontal and parietal atrophy are also seen. Third ventricle is usually dilated.

Above image shows the method of assessing for Morning Glory sign.

Again a normal patient with convex lateral margin of tegmentum.

Above image showing the concave lateral margin of tegmentum, termed as the Morning Glory Sign, which has been stated as a more specific sign of Progressive Supranuclear palsy.

Above images shows the comparison with a normal midbrain showing the superior convex contour and that of an atrophic midbrain showing concave superior contour in a Progressive Supranuclear Palsy patient. The appearance is likened to that of a Humming Bird.

Note : In the original article, the Morning glory sign, is described as the authors saw a likeness of atrophied midbrain to the lateral view of morning glory flower.

References :
1. Magn Reson Med Sci. 2004 Dec 15;3(3):125-32. Morning glory sign: a particular MR finding in progressive supranuclear palsy. Adachi M(1), Kawanami T, Ohshima H, Sugai Y, Hosoya T.
2. CT and MRI of the Whole Body, 6th Edition, John.R.Haaga, Elsevier Publications.
3. Humming bird and Morning glory images from pixabay.com , under CC0.

What's 'GRE Susceptibility Vessel Sign' ?

(Above image showing the Susceptibility Vessel Sign : hypointense signal on SWI of right vertebral artery (V4 segment), more or less equivalent to hyperdense Vertebral Artery on CT).

Thrombi are mainly of three types based on their composition : platelet rich (white) thrombi, red thrombi containing rich fibrin network and RBCs and finally the mixed ones. White thrombi are formed mainly in atherosclerotic plaque ruptures, where as red thrombi are formed in low pressure systems like cardiac or venous systems.

The oxyhemoglobin which gets degraded into de-oxy hemoglobin, methemoglobin and hemosiderin, all have paramagnetic properties and produces susceptibility artifacts in GRE images. This concept is the main core of Susceptibility Vessel Sign.

Teaching Point : GRE SVS is associated with red thrombi and thereby favors a Cardio-Embolic Stroke in most cases. And it also signifies increased chance of subsequent spontaneous recanalization and also increased success rates with fibrinolytic therapy. 

 

Exceptions :

1.SVS –ve cardio-embolic thrombi : 

Can occur if MRI was taken before the degradation of Oxy-Hb to Deoxy-Hb (which usually occurs in few hours) OR due missing the section of small thrombus in GRE due to the interslice gap.

2.SVS +ve (Large Artery) Atherosclerotic thrombi :

due to the formation of white thrombus initially, can lead to stagnant or reduced flow velocity within the vessel, there by gradually causing increased fibrin and RBC content of thrombus.


References :
1. Significance of Susceptibility Vessel Sign on T2*-Weighted Gradient Echo Imaging for Identification of Stroke Subtypes. Kyung-Hee Cho, MD; Jong S. Kim, MD, PhD; Sun U. Kwon, MD, PhD; A-Hyun Cho, MD; Dong-Wha Kang, MD, PhD. Stroke, November 2005.

What's your Diagnosis? : Question 1

ANSWER HERE...