Geraldine Liao, MD

A 33-year-old male with history of cyanotic congenital heart disease status post multiple palliative cardiac surgeries, atrial fibrillation on warfarin, presents with altered mental status.

Normal enhanced CT examination of the head


There is no acute intracranial hemorrhage, acute infarct, or other acute abnormality. The intracranial vasculature appears hyperdense due to increased hematocrit.

Chronic hypoxemia secondary to right-to-left shunting in this patient with cyanotic congenital heart disease results in compensatory increased hematocrit. This patient had a hematocrit of 66% (normal 40%-52%).


On an unenhanced CT examination of the head, normal flowing blood within the intracranial arteries are approximately 40 Hounsfield units (HU). Increased hematocrit, whether diffuse or focal, such as in thrombus, results in increased intraluminal attenuation (approximately 80 HU). This is the basis of the “hyperdense vessel” sign due to intraluminal thrombus, where extrusion of serum and clot retraction results in focal intraluminal hyperattenuation. This may also be seen in the venous sinuses with venous sinus thrombosis. Care must be taken to differentiate the hyperdense vessel sign from intracranial atherosclerotic calcification.

Overall increased hematocrit results in diffusely increased density of the vessels due to hemoconcentration. In this patient, increased hematocrit is a compensatory mechanism for chronic hypoxemia due to the patient’s right-to-left shunt cardiac physiology. Diffuse hyperattenuation of the vessels may mimic a contrast-enhanced CT examination, such as in this exam.

Another mimic of hyperdense vessels is diffuse cerebral edema resulting in relatively low density of the brain parenchyma compared to the vasculature.


Black DF, Rad AE, Gray LA, Campeau NG, Kallmes DF. Cerebral venous sinus density on noncontrast correlates with hematocrit. 

Ledezma CJ, Wintermark M. Multimodal CT in stroke imaging: new concepts.

Mullins ME. The hyperdense cerebral artery sign on head CT scan. 

Poll

33-year-old male with history of cyanotic congenital heart disease status post multiple palliative cardiac surgeries.

Image IQ: History of Cyanotic Congenital Heart Disease

A 29-year-old female presents with chronic right knee pain. She has a history of right knee injury after a fall 4 years ago.

Acute avulsion fracture of the medial femoral condyle

Chronic injury of the medial collateral ligament

Tricompartmental osteoarthritis of the knee

Diagnosis: Chronic injury of the medial collateral ligament


Knee radiographs demonstrate mineralization adjacent to the medial femoral condyle. MRI demonstrates thickening and intermediate signal of the proximal medial collateral ligament without associated surrounding edema. There is ossification within the proximal portion of the medial collateral ligament.

There is also cortical irregularity and mild depression of the lateral tibial plateau without associated edema.


The radiographic and magnetic resonance imaging findings are consistent with a chronic injury of the medial collateral ligament.

Acute medial collateral injury typically occurs when a valgus force is applied to the knee (eg, a direct lateral blow). This can occur in isolation or as part of a more complex injury mechanism.  Associated injuries include anterior or posterior cruciate ligament injury and medial or lateral meniscal tears. Acute injuries are graded on a scale of I to III with increasing severity. Grade I represents a mild sprain with edema surrounding the ligament, grade II represents a partial tear with abnormal signal within the ligament, and grade III represents a complete disruption.

Prior injury may result in dystrophic calcification or ossification of the ligament, typically of the proximal portion. This is known as Pellegrini-Stieda disease. The ligament appears thickened, but without abnormal signal or surrounding edema. The ossific fragment is typically low in signal intensity on both T1- and T2-weighted images, but may be high signal in T1-weighted images if it contains fatty marrow.


Miller TT. Imaging of the medial and lateral ligaments of the knee. 

Niitsu M, Ikeda K, Iijima T, Ochiai N, Noguchi M, Itai Y. MR imaging of Pellegrini-Stieda disease. 

29-year-old female with history of remote right knee injury. 

Image IQ: History of Remote Right Knee Injury

A 9-year-old male presents with acute onset abdominal pain with fever, vomiting, and diarrhea.  His abdomen on exam was mildly distended and diffusely tender to palpation, especially in the right upper quadrant and right lower quadrant.

Ultrasound demonstrates a blind ending tubular structure in the right lower quadrant measuring approximately 1 cm in luminal diameter.


Ultrasound images demonstrate a thick-walled, distended appendix with significant hyperemia.  A 1.5-cm appendicolith is seen at the proximal end of the appendix. There is surrounding fat stranding, as well as a small amount of free fluid.


Ultrasound is often the first line imaging modality in children presenting with acute abdominal pain because of its lack of ionizing radiation. Sonographic findings of acute appendicitis include visualization of a blind-ending tubular structure greater than 6 mm in outer diameter, corresponding to a dilated appendix, non-compressibility of the appendix, and hyperemia of the appendiceal wall. Occasionally, a highly echogenic appendicolith may be visualized as well.  Secondary signs include hyperemia on color Doppler and inflammatory change of the surrounding mesenteric fat, as well as bowel wall thickening of adjacent small bowel loops and cecum.


Lee JH. Sonography of acute appendicitis. 

9-year-old male presents with acute onset abdominal pain with fever, vomiting, and diarrhea.

Image IQ: 9-year-old Male with Abdominal Pain

10-year-old male presents to the emergency department with left testicular pain and swelling for the last four days. He complains of increased pain when ambulating and with coughing.


There is enlargement of the left epididymal head, with hyperemia of the epididymis and adjacent left testicle. There is also marked swelling of the overlying scrotal skin. There is incidental microlithiasis of both testicles. The right testicle is otherwise normal.


The most common cause of acute scrotal pain in adolescent boys and adult men is acute epididymitis. Common causes in sexually active men are 

 being other common causes. Epididymitis can spread to the testicle to become epididymo-orchitis in 20%–40% of cases, such as in our example.

On ultrasound imaging, the epididymis is enlarged and hyperemic. Spectral waveform can demonstrate decreased vascular resistance when compared to the normal contralateral side. Other signs of inflammation may be present, such as a reactive hydrocele or scrotal wall thickening. Secondary involvement of the testicle will demonstrate enlargement, hyperemia, and be somewhat heterogeneous in echotexture.

Testicular microlithiasis results from calcium deposits within the seminiferous tubules, which sonographically appear as multiple punctate echogenic foci within the testes. A series of retrospective studies previously demonstrated correlation between testicular microlithiasis and increased incidence of testicular cancer; however, newer studies have called the association into question. It is unclear whether routine sonographic surveillance is of benefit to patients with testicular microlithiasis, though the exam is non-invasive and poses little risk to the patient.


Dogra V, Bhatt S. Acute painful scrotum.  

Richenberg J, Brejt N.  Testicular microlithiasis: is there a need for surveillance in the absence of other risk factors? 

10-year-old male presents to the emergency department with left testicular pain and swelling for the last four days. 

Geraldine Liao, MD

Articles

Image IQ: History of Cyanotic Congenital Heart Disease

Image IQ: History of Remote Right Knee Injury

Image IQ: 9-year-old Male with Abdominal Pain

Image IQ: 10-year-old Male with Left Testicular Pain and Swelling