Saturday, July 30, 2011

Primary Tubercular Complex-Plain CXR


A young child with cough and fever

Chest Xray shows subsgemetnal atelectasis with transverse fissure thickening with hilar lymphadenopathy and mottled infrahilar reticulation possibly lymphangitis – together called primary complex disease(Ranke’s complex)


Teaching points by Dr MGK Murthy

-       Tubercle bacilli as little as 1-3 can reach the respiratory tree  of the child invariably from cavitating adult contact usually at home or school/daycare environment as the bacilli are  really killed by ultraviolet light outside
·       The bacilli can be expelled by the cilia to be swallowed and destroyed by the stomach acid or can reach alveoli to be inhibited/killed by the macrophages.
·       If they are virulent , multiply and burst macropahges to spread forming tubercle (aggregation of macrophages, epitheloid cells and lymphocytes)
·       Immune response at this stage(3-8 wks) is delayed hypersensitivity and tuberculin test is positive
·       Bacilli escape from edge, multiply and reach lymphnodes .
·       All the 3 components alveolar site (ghon’s focus), lymphangitis and infected mediastinal lymphnode form Primary complex mediated by cell mediated immunity (Ranke’scomplex)
·       Chest Xray/CT is + by 4-8 wks after the exposure
·       Can involve any part  of the lung but middle lobe is least involved
·       95%do not suffer from disease and X ray  shows only fibrosis, calcification or completely normal
·       Radiological hallmark is lymphadenopathy
·       Because of peculiarity of lymphatics, left parenchymal lesion produces bilateral and right parenchymal shows only right hilar  lymphnodes possibly along with transverse fissure fluid
·       When the lesion erodes the lymphnode and spreads along the bronchus it will become progressive primary TB
·       If TB infection occurs 1 year or later after the original infection, referred to as post primary from usually because of reactivation
·        Post primary prefers colonization in upper lobes specially apical and posterior segments
·       Child to child transmission is rare because of lack of tussive outburst
·       Miliary and Meningeal forms develop in 1st 3months after primary complex
·       Pleural and peritoneal forms take 3-7 months to manifest
·       One variety called congenital TB is extremely rare possibly because  of hypoxic intrauterine environment does not promote TB bacilli growth.
·       But when occurs ,usually via transplacental spread-----primary complex is in liver –periportal LNs –other organs and lungs can remain latent for 2-4 wks after birth and when Xray is +, it shows miliary form
·       Even more rarely can occur by foetus swallowing bacilli in genital TB

FDA alerts healthcare professionals about-CardioGen-82 -PET

The U.S. Food and Drug Administration (FDA) is alerting healthcare professionals to stop using CardioGen-82 for cardiac positron emission tomography (PET) scans due to radiation concerns. The manufacturer, Bracco Diagnostics, Inc. has decided to voluntarily recall CardioGen-82.

Thursday, July 28, 2011

Lesser Toe Fracture-Plain Xray


A Young adult with injury to toe

Teaching points by Dr MGK Murthy.



&Fracture of middle phalanx proximal portion is  appreciated  only on oblique view and this view is mandatory for toes
&Fracture is of avulsion variety
&Two types  of fracture that occur at proximal portion of middle phalanges of lesser toes –one is spiral and other is avulsion
&Flexor and extensor tendons are attached here and joint hyperextension leads to this type of fracture
&Proximal portion of proximal phalanges  give attachment to Interossei, Abductors and  Adductors
&Stress fractures occur at medial base of proximal phalanges in athletes and are identified only on review radiographs after 2 weeks
&Lesser toes fractures are 4 times more common than great toe
&One must always look for multiple phalanges injury as it is common 

Monday, July 25, 2011

Silicosis- CT Findings

This is a 59 year old male with history, working in mine company.  Possible silicosis with small nodular shadowing and relative sparing of the lung bases.


CT findings in Silicosis:

Small well-defined nodules of 2 to 5mm in diameter in both lungs.
Upper lobe predominance
Nodules may be calcified
Centrilobular and subpleural distribution
Sometimes random distribution
Irregular conglomerate masses, known as progressive massive fibrosis
Often hilar and mediastinal lymphnodes.




Thursday, July 21, 2011

Cauda Equina Tumour-Differentials


29 yr old lady comes with gradually increasing pain and weakness of both lower limbs  including buttocks region. Routine MRI shows solitary, enhancing, well defined ,glomus shaped , nodule intramedullary region possibly  from filum  terminale internum with separation of nerve fibers of cauda at L3 level with no clumping of nerve roots or bony anomaly or disc disease  or conus  disease. Case by Dr MGK Murthy and Mr Hariom.





What is the diagnosis ?
It is of  intramedullary  neoplastic etiology and probably represents    ependymoma (commonest in this region, enhancement, and age group)

Differentials include extruded discs (not likely as no significant disc prolapse is identified otherwise and  the enhancement  ) spinal haemangioblastoma (no mural nodule), neurofibroma and schwannoma(not homogenous and intense in enhancement  as  well as no extension along the intervertebral foramina),Lipoma, dermoid and epidermoids (though relatively bright on T1, enhancement  goes against these),meningioma(though T2 low , enhancement is not typical and location is unusual), paraganglioma(intense enhancing nodule is the rule )and lastly the ever mimicker of neoplasm in our country tuberculoma (no other evidence of TB otherwise )

Teaching points:
-Spinal cord ends at lower border of L1 as conus in adults
-filum continues as strand of connective tissue for 15 cms appx with first 5-6 cms having central canal as well
-filum terminale internum continues as externum to coccyx after piercing the dura caudally

Sternal Tuberculosis-CT


35 year old female with fever and sternal mass, CT shows evidence of osseous destruction involving the sternum with associated peripherally enhancing soft tissue component extending into both intra & extrathoracic region possibly consistent with associated abscess formation, likely tubercular in nature.



Friday, July 15, 2011

Is 3 Tesla MRI ready to be the new work horse scanner?

Advantages: On a physics basis 3T MRI has better signal to noise. 3T the extra signal makes you able to cut thinner or scan with higher resolution. Quality of the brain MRI studies at 3T is exceptional with a smooth depiction of the gray what matter junction and added sensitivity to hemorrhage. In the musculoskeletal system 3T is king. All musculoskeletal studies are improved by the higher resolution, better fat sat and contrast sensitivity.

Challenge in Body Imaging: But new acquisition techniques such as multitransmit made available at 3T, can reduce B1 inhomogeneity artifacts and improve effectiveness in body imaging.

Heating up of non-ferrous implants: Some implants which are non-ferrous can heat up and cause burns when in a more powerful magnet environment. Part of having experience at 3T is to understand where you might run into a SAR issue and know immediately how to deal with it. The simple easy answer is when you hit a SAR barrier accelerate over it. It works most of the time. In the cases where it does not work – switch to gradient echos which deposit less SAR. Coronary Stents: The greater heat production due to thermal relaxation although not proved to make a big problem with cardiac stents but it should be investigated thoroughly.

By going through above discussion, i personally feel 3Tesla would soon be the work horse scanner. What are your views on this? Please feel free to share opinion in comment section.

Thursday, July 14, 2011

TRIANGULAR FIBROCARTILAGE COMPLEX- MRI


Teaching points about TFCC by Dr MGK Murthy & Mr Abdul Hamid





- Normally responsible for ulnar sided wrist pain.
- Thickness is inversely related to ulnar variance with negative ulnar variance patients  having thicker TFCC.
- Normally is 1 to 2 mm thick at most locations with subtle increased upto 5 mm in the vicinity of eccentric concavity of the ulnar styloid.
- Being of type-I collagen is usually dark on all sequences like  the knee ligaement.
- Coronal fat suppressed sequence is most appropriate for study of TFCC.
- The blood supply is usually well maintained at the periphery with relatively avascular centre which leads to central perforations not healing well.
- Dorsal and the palmar branches of the anterior introsseous artery along with dorsal and the palmar branches of ulnar artery supply TFCC. 
- Has attachments to lunate, triquetral, hamate and base of the 5th metacarpal.
- Closely approximated to extensor carpi ulnaris tendon and associated injuries are common.
- MDCT Arthrography of the wrist  is suggested to be superior in some studies, to MR Arthrography or Conventional Arthrography.
- Degeneration starts in 3rd decade with heterogenity being the rule by the 4th decade.

Tuesday, July 12, 2011

CME Alert-American Roengten Ray Society

Fall Symposia - Register Today at www.arrs.org


Abdominal CT Symposium- Designed for the generalist, this symposium offers as an excellent overview of Abdominal CT while providing practical reviews and cutting edge technology updates. Walk away with tools you can use in your everyday practice.


Breast and Women's imaging symposium- During this 3 ½ day symposium you will learn how to detect, diagnose, and treat breast and gynecologic diseases. Walk away with strategies to manage these 
diseases.  Connect with renowned faculty who will provide a wide variety of women’s imaging expertise from around the world.

Monday, July 11, 2011

Customized Estimated Fetal Weight Calculator


Link to an excellent reference estimated fetal weight is available here with inputs including parity, ethnic race, maternal height and weight. 


References Gardosi J, Mongelli M, Chang A. An adjustable fetal weight standard. Ultrasound Obstet Gynecol 1995;6:168-174
http://www.gestation.net. 

Saturday, July 09, 2011

Os Radiale Externum -Plain film

11yr old child with history of trauma. Professor-resident series by Dr MGK Murthy.

How do we read this picture?
An ill defined irregular radio opacity seen dorsal surface of scaphoid  with no significant soft issue abnormality.



is it a fracture?
In this case that is difficult  to answer precisely as the comparative picture for other side does not show this and usually the accessory ossification center for this region called Os Radiale Externum  is bilateral.

 How do we report?
The interpretation for this radiograph should be as fracture until follow up X -ray after 2 weeks is performed

 Is cross sectional imaging helpful?
Unlikely as  both CT and MRI are only likely to suggest the lesion in better demonstration and  growing accessory ossification center at times is difficult to separate from fresh fracture.  Of course MR may demonstrate the soft tissue delineation better

How about nuclear medicine ?
Not likely to play major role for the same reason

What is the best way out for the child?
I  would go by the local tenderness as scaphoid fracture has been diagnosed by tenderness from time immemorial. I would request the clinician to treat the lesion as fracture until 2 weeks repeat X ray and Fracture never stays quiet for 2weeks and any sign of healing and callus is good enough suggestion. In this patient, as there is no displacement, it needs to be treated conservatively in any case 

Teleradiology in Outer Space

"Researchers with the NASA-funded National Space Biomedical Research Institute (NSBRI)  have developed a guide aimed at enabling astronauts to administer and interpret their own ultrasound exams from space. Previously, astronauts had used ultrasound under the guidance of specialists back on Earth, who then read the images remotely. The researchers’ projects have both enhanced this teleradiology process and enabled self-review of images for certain exams."

Reference and further reading-

Monday, July 04, 2011

Intramedullary Metastases-MRI


An elderly person with known small cell cancer of lung comes with neurological deficits and has demonstrated solitary ,expansile,  intramedullary SOL consistent with intramedullary  metastases . In addition brain metastases are appreciated. Case by Dr MGK Murthy and Mr A.Hamid



Teaching points

4 possible routes are suggested for occurrence
(a)  Arterial haematogenous-supported by the fact that 61% of all intramedullary metastases patients have multiple sites of cerebral and spinal lesions
(b)  Venous route from pelvis by vertebral batson’s venous plexus is suggested
(c)     Leptomeningeal dissemination by CSF
(d)   Direct contiguous spread from the neighboring organs by penetrating the normally protective dura

CEMR is the gold standard with typical lesion described as small, oval, small, with little or no spinal cord defect , with heterogeneous nodular enhancement and pencil thin,  non enhancing , edema more in the cranial aspect. 

Is calcium scoring relevant for African Americans?

African Americans may have less stable lesions than whites due to significantly higher volumes of noncalcified plaque, according to a study published June 21 in Radiology, which may suggest that coronary CT angiography may be a more appropriate screening study than calcium scoring among African Americans.

Saturday, July 02, 2011

Google Plus -New one in the social network game

Google takes swing at the social network game dominated by Facebook. Google has now announced a service called “Google+” that promises the Web search people know and love, plus updates of what your friends are doing, thinking, photographing and sharing. Right now it is by invitation only. Lets wait and watch out for it.

Friday, July 01, 2011

Total Knee Arthroplasty for Radiologist


A total knee replacement complains of pain. Xray AP and lat show good alignment of the components along with possible loosening of the tibial stem with no periosteal response or sign of osteomyelitis. Case by Dr MGK Murthy



Best TKA accepted today is Cemented Total Knee replacement(life span=finite period, depends on use). Knee ligaments to be preserved or not is still debated .Results are equal for both  though gait is better if ligaments are preserved. Types- Fixed bearing/Medial pivot/Rotating platform and mobile bearing/PCL retaining/PCL substituting

Pre Op Radiographic workup

X -rays-Standing—AP/Lat/Skyline view
Long leg X -ray for malalignment
Standing X -ray with Knee in extension  or 45°flexion(Rosenberg view)(can show cartilage degeneration better)


Contraindications
-sepsis/Extensor mechanical dysfunction/secondary vascular disease/Recurvatum secondary to muscular weakness with neuropathic joints and obesity being relative contraindications

Surgical alternatives to TKR
-proximal tibial osteotomy(for medial compartment disease)
-Distal femoral varus osteotomy(for lateral compartment disease)
-Unicompartmental Knee replacement

Post Operative Radiographs

-       Malalignment

-       Aseptic loosening of stem (either bone ) more often tibial
5-10%of patients at 10-15 yrs have loosened stem
cause is not known, but possibly polyethylene debris ---------- alteration leading to bone--------mechanical instability---Treatment is with revision surgery with bone grafting


-Arthrofibrosis
cause is not known
basically excessive scar tissue
more in young and on warfarin patients
Less than 1% of TKRs lead to this
conservative treatment or revision surgery with resection is the answer









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