Thursday, December 20, 2018

MRI Hepatic Lesion Differential Diagnosis


This post is derived from notes I took during training. Any images are copyright their respective owners.

Focal nodular hyperplasia (FNH)
  • Demographics: young women 
  • Pathology: localized hyperplastic hepatocyte response to an underlying congenital arteriovenous malformation 
  • MR: fibrous central scar that is T2↑, T1↓ with delayed, enhancing scar 
  • US: internal vascularity in spoke wheel configuration 
  • NM: Uptake ↑ on sulfur colloid scan due to Kupffer cell uptake. HIDA positive. 
  • Differential: Adenoma (photopenic on sulfur colloid)

Hepatic adenoma
  • Demographics: Young women on contraceptives
  • MR: mixture of fat, hemorrhage, necrosis; fat will be T1 bright, drops out on opposed phase imaging; may see internal vascularity / hyperintense capsule; if bleeding, may see hematoma as below 
  • Management: Monitor for size; if greater than 4 cm, treat because of bleeding risk




Hepatic hemangioma

  • Most common benign liver mass, not prone to spontaneous bleeding 
  • US: Homogeneously echogenic with no flow on Doppler. Never see hypoechoic halo. 
  • CT/MR: typically early discontinuous nodular filling, fills centripetally
    if cavernous/large, may have central hypointense scar +/- calcification 
  • NM: delayed blood pool activity on Tc99m RBC has nearly 100% PPV

Hepatocellular carcinoma (HCC)
  • Demographics: older pts 
  • Pathology: associated with cirrhosis; MC primary hepatic malignancy. AFP elevated. 
  • MRI: hypointense but with rapid uptake and early washout. Portal vein invasion. 
  • Differential: regenerative nodules (not hypervascular, no PV invasion), regenerative nodular hyperplasia (associated with Budd-Chiari, resemble FNH) 
  • Treatment: Chemo, Ablation, Surgery 
Fibrolamellar HCC
  • Demographics: young adults, may have h/o hepatitis 
  • CT/MRI: Large, calcified central scar; heterogeneous appearance 
  • Differential: FNH (smaller, older patients, more homogeneous appearance, enhancing scar)


Metastases
  • Children: Neuroblastoma (Stage 4 & 4S), Burkitt, Wilms, AML, Sarcomas 
  • Adults: 
    • Hyperechoic: Colon, RCC, Breast (either), Carcinoid, Chorio 
    • Hypoechoic: Breast (either), pancreas, lung, lymphoma 
    • Calcified: colon (mucinous type), gastric, osteosarcoma (rare) 
    • Cystic: ovarian cystadenoca, GI sarcoma 
    • US: hypoechoic rim (target sign)



References:



     

Tuesday, December 18, 2018

How To Read A Shoulder MRI

Shoulder MRI is a common musculoskeletal imaging exam. The exam is typically ordered for shoulder pain with suspicion of underlying rotator cuff pathology. Contrast is not needed. If there is a concern for labral pathology, an MRI arthrogram may be ordered. The arthrogram requires gadolinium-based contrast to be injected intra-articularly under fluoroscopic guidance prior to the MRI. The steps below are for a routine, non-contrast MRI.

The MRI shoulder is usually acquired in 3 planes (axial, sagittal, and coronal) obliqued to the plane of the scapula. Usually each plane is acquired as PD and T2, with one of the planes being done as a T1 instead of PD.

Prior to looking at the MRI, it is helpful to compare with any prior shoulder x-rays available.

On the MRI, the assessment should include:

  • Long heads of the biceps tendon: Start on the axial sequences and follow it along its course in the bicipital group to its origin at the biceps labral anchor
  • Supraspinatus
  • Infraspinatus
  • Teres Minor
  • Subscapularis: fluid in the subcoracoid bursa is suggestive of a tear [1]
  • Rotator Interval [2]
  • Labrum: best seen on the axial and coronal sequences; should appear hypointense and symmetric. Better assessed on MR arthrogram. 
  • Coracohumeral ligament: best seen on the coronals as a hypointense structure arising from the lateral coronoid
  • Inferior glenohumeral ligament: also assessed on the coronal; greater than 4 mm in capsulitis
  • Acromioclavicular joint
  • Humerus and other bony structures
  • Spinoglenoid notch
  • Suprascapular notch
  • Quadrilateral space


This post is derived from notes I took during training. Any images are copyright their respective owners.

Revised: 2019-01-14

References:



     

Monday, September 17, 2018

Spondylosis, Spondylolysis, Spondylolisthesis, and Spondylitis

Spondylosis, Spondylolysis, Spondylolisthesis, and Spondylitis are four terms that are easily confused for one another. All refer to specific pathologies of the spine. Hopefully the descriptions and explanation below will help you break down each word and remember the distinctions.

To distinguish each word, ignore the prefix spondyl- , which comes from the Greek spondylos, meaning vertebral body. Focus on the suffixes.

Spondylosis

The suffix -osis here refers to any pathology, but usually is referring to degenerative changes of the spine.

Spondylolysis

The suffix -lysis refers to the breakdown or absences of bone, specifically pars defects, most commonly found in the lower lumbar spine at L5-S1.

Spondylolisthesis

In this context, -listhesis refers to the alignment of spine. For specificity, the term anterolisthesis refers to the more superior vertebral body being more anteriorly positioned relative to the next inferior vertebral body. Retrolisthesis is the reverse.

Spondylitis

As in many other conditions, the suffix -itis refers to inflammatory changes (i.e. arthritis). A common form of spondylitis is ankylosing spondylitis, a HLA-B27 seropositive arthropathy.

Spondylosis, Spondylolysis, Spondylolisthesis, and Spondylitis Explained
Source: Huffington Post 
Hopefully these definitions clear up the confusion among these entities. Remember, focus on the suffix in order to figure out the disease process being discussed.

This post is derived from notes I took during training. Any images are copyright their respective owners.

References:



     

Monday, September 10, 2018

How To Read An Abdomen-Pelvis CT

Abdominal pain is a very common chief complaint, especially among ER patients. While the truism of "look at every organ on every image" applies, this is the reading pattern I have developed for myself over time.
  • Bones - look in sagittal and axial. Make note of any pars defects around L5. For trauma cases, consider looking in coronal as well for femoral and sacral pathology.
  • Lung bases / lower thorax - look in lung windows. Glance at heart/pericardium 
  • Aorta / Retroperitoneum -  look for aneurysms, dissection, and lymphadenopathy
  • Liver / Gallbladder - scroll from inferior to superior, looking at the right hepatic parenchyma and hepatic veins. Then scroll from superior to inferior looking at the left hepatic lobe. Scroll back through the gallbladder and biliary ducts. Lastly, scroll inferiorly from the right and left portal veins to the portal vein down the SMV.
  • Pancreas - after you scroll through the portal veins, scroll back up the pancreas from the uncinate process through the head, body, and tail.
  • Spleen - look from pole to pole.
  • Stomach / Duodenum - look from the gastroesophageal junction through the third portion of the duodenum.
  • Adrenals
  • Kidneys - look in axial and coronal planes to exclude any exophytic lesions.
  • Bladder / Pelvis - scroll down from the kidneys along the ureters to the bladder
  • Colon - look at rectum, sigmoid, descending, transverse, ascending colon, cecum, and appendix in that order. 
The advantage of this scan pattern is that you mostly scroll continuously, avoiding jumps between different areas of the abdomen/pevis. Of course, specific chief complaints will lead to a focus on other particular areas of interest. Compare any findings with any prior comparison studies available. 

This post is derived from notes I took during training. Any images are copyright their respective owners.



References:



     

Tuesday, September 4, 2018

Guest Post: How To Become A Radiologist

This post details all the steps necessary for a student to go on the journey towards becoming a practicing, board-certified radiologist in the United States:

How to Become a Radiologist

A radiologist is a physician who specializes in using a wide array of techniques that use advanced medical imaging to diagnose, and even sometimes treat, patients with a wide array of illnesses.

These specialists use the tools at their disposal to help them provide patients with the best possible skill and results. Some of the tools of the trade they have to assist them in diagnosing and sometimes helping to treat their patients include ultrasounds, X-rays, MRIs, and CT scans. Like any other physician, in order to be a radiologist, one must have completed medical school and have earned their MD degree.

Radiologists work in correlating the medical histories of their patients, as well as their lab values and exam findings, and their interpretations of the imaging, to aid both patients and their doctors to arrive at a proper and accurate diagnosis in a timely manner.

Today, there is an increasing subset of these specialists, called interventional radiologists. This type of radiologist performs surgical procedures using guidance of imaging techniques to minimize damage done to healthy tissues in the body.

Are you thinking of becoming a radiologist? If so, it’s important to know up front that the training can be competitive, long, and intense. However, the payoff of being able to help so many people makes the journey well worth the effort that it entails.

If you think this is a journey you’re ready to embark on, then you should first know what you’ll have to do to reach your goal. Here’s what it entails:

Get Your Bachelor’s Degree


In order to become a radiologist, you need to first go through the educational track. The first step is to get a bachelor’s degree from an accredited university or college. Before you enroll in any university to get a bachelor’s degree, ensure that it is an acceptable institution in the eyes of any medical school. With the help of the academic counseling center, you can get help in reviewing what different medical schools are looking for in an undergraduate degree program.

Take the MCAT (Medical Colleges Admission Test)


The MCAT test is a standardized, multiple choice exam that is administered in a period of four and a half hours. Before taking this test, it is advisable to review what will be on the exam and make sure you are well-versed in all the subject areas it covers. The skills and knowledge it tests include problem solving skills, critical thinking, fluency in social science concepts, and the knowledge needed to be able to study medicine effectively.

Become a Medical Doctor

In becoming a medical doctor, you have three options to choose between when it comes to deciding on the medical degree program that is right for you.

Get a Medical Degree (M.D.)


This focuses on the traditional diagnostic methods, as well as their treatments and medicinal therapies.

Become a Doctor of Osteopathic Medicine


This profession focuses on caring for and studying the musculoskeletal system of the human body.

Become a Doctor of Philosophy with a Medical Degree


Many schools offer a combination degree that allows you to obtain a M.D. and a Ph.D. This gives you two career path options, and offers increased financial support as well as fast tracking your ability to get a medical degree. This is because many schools offer a 3-year M.D. program for Ph.D. graduates.

Declare a Radiology Specialty


The third and fourth years of medical school involve clinical rotations. Early in the fourth year, you should have an opportunity to declare your specialty in radiology.

Pass the USMLE or the COMLEX


These tests stand for the United States Medical Licensing Exam (USMLE) and the Comprehensive Osteopathic Medical Licensing Exam (COMLEX). It is necessary for any aspiring radiologist to pass one of these exams to be capable of practicing their profession.

Complete a 4-Year Residency Program in Radiology


The United States is home to about 218 radiology residency programs, which offer around 890 positions annually.

Become Board Certified


In order to get certified, check the requirements on the American Board of Radiology’s website. Certification exam times are available there, as well as information to become Board Certified in your subspecialty of choice.

Get a Job

Once you have done all this, you’re ready to become a radiologist! You’re completely certified and ready to take on the job and begin helping people. The final thing you need to do is apply to jobs until you find one suited to you. It’s a good idea to look at public and private hospitals, as well as staffing agencies, medical groups, private practices, and teleradiology groups, to find a job opening.

At this point, you might think that your education is over, but actually, you’ll have to keep taking radiology courses in order to stay up to date on the latest technology and trends in the industry.

Start Helping People!


The last thing you need to do is start doing your job! Enjoy being a radiologist and the rewards that come with the job, including being able to help countless patients stay or get healthy!


Toni May works for a radiology CME company.