RiTradiology

Triquetral Fracture

rathachai@gmail.com — Sat, 21 Jan 2012 00:00:00 +0000

A lateral wrist radiograph shows a small bone fragment (arrow) dorsum to the wrist with overlying soft tissue swelling.

Facts:

Second most common carpal bone fracture
Two main types: dorsal chip fracture and body fracture
Dorsal chip fracture (like in our case ) believed to be due to forceful impingement of the triquetrum during wrist hyperextension
Body fracture frequently associated with perilunate dislocation (direct blow)
Pain and swelling localized at the dorsum of the wrist where triquetrum is located
Complication: motor branch of ulnar nerve injury

Imaging

Chip fracture best seen on lateral radiograph with hand in flexion
Body fracture best seen on AP and oblique radiographs
Fractures are possibly underreported. CT can help in suspected cases.

Reference:

Simon RR, Koenigsknecht SJ. Emergency orthopedics: the extremities, 2001.

Pneumothorax on Ultrasound

rathachai@gmail.com — Tue, 10 Jan 2012 00:00:00 +0000

M-mode ultrasound images of the lungs (right and left) show a normal "lung sliding" on the right side "Right" and absence of it on the left side "Left".

Facts:

Ultrasound can be performed to diagnose pneumothorax with high accuracy
Normal "lung sliding" is seen when pleura moves against the chest wall during respiration. The movement is easily seen on real-time imaging and can be captured on M-mode ultrasound
M-mode US shows normal lung sliding as a "seashore sign", in which the motion of pleura/lung produces sand-like granular appearance on the image. The non-mobile chest wall shows several uninterrupted band or "sea"
Some diseases may produce "loss of lung sliding", most notably pneumothorax

Pneumothorax on US

Absence of lung sliding shown on real-time imaging
On M-mode as "barcode sign" or "stratosphere sign" (see above image labeled "left")
More specific sign is the "lung point sign"

Our case: left pneumothorax (confirmed with radiography)

Reference:

Lichtenstein DA, Menu Y. A bedside ultrasound sign ruling out pneumothorax in the critically ill. Chest 1995; 108:1345-48.

Calcification in Lung Nodule

rathachai@gmail.com — Sat, 31 Dec 2011 00:00:00 +0000

A spot chest radiographic view of the left lower lung zone (with a nipple marker) shows a 1-cm nodule (arrow) in the lung base just medial to the nipple marker.

Non-contrast CT confirms the presence of a nodule in the left lower lobe (arrow) that contains a central calcification.

Lung Nodule Calcification

Up to 6% of lung cancer have calcification. Therefore, calcium in a nodule does not exclude possibility of lung cancer
Suspected malignant nodule if calcium is.... eccentric, amorphous or it involves only a small portion of the nodule
Benign: central (>10% of cross-sectional area of nodule), diffuse and laminated calcification
Nodules that are nonsolid or partly solid are more often malignant

Our case: benign nodule, likely a granuloma.

Reference:

Hodler J, von Schulthess GK, Zollikofer ChL. Diseases of the Heart, Chest & Breast 2011-2014. Springer-Verlag Italia 2011.

Sternoclavicular Rheumatoid Arthritis

rathachai@gmail.com — Wed, 21 Dec 2011 00:00:00 +0000

Axial CT images of the sternoclavicular joints show erosion, indistinct cortical margins of the joints, which are quite symmetric.

Facts:

Sternoclavicular (SC) joint is diarthrodial articulation between axial and appendicular skeleton, which is subject to same disease process that occur in other joints (degenerative arthritis, rheumatoid arthritis, infection and subluxation. Degenerative arthritis is the most common).
Up to 30% of patients with rheumatoid arthritis have changes in SC joints (a part of polyarticular involvement) but radiographic findings are often unremarkable.

Imaging Finding

Synovitis
Bone marrow edema and enhancement of subcortical bone (after IV contrast)Er
Erosion and indistinct cortical margins
Think infection if: unilateral, history of IVDU and immunocompromised states

References:

1. Restrepo CS, Martinez S, Lemos DF, et al. Imaging appearance of the sternum and sternoclavicular joints. Radiographics 2009; 29:839-859.

2. Berry DJ, Steinmann SP. Adult Reconstruction, 2007.

Scrotal Pyocele

rathachai@gmail.com — Sun, 11 Dec 2011 00:00:00 +0000

Gray-scale and color Doppler US images of the testicle shows a complex fluid collection (stars) around the testicle and marked scrotal skin thickening. The epididymis is edematous with increased flow (image not shown).

Facts: Scrotal Pyocele

Also known as scrotal abscess
Can be superficial (from infected hair follicles, wound) or intrascrotal
Causes: epididymitis, TB, instrumentation, neurogenic bladder, chronic catheter indwelling, spread from intraabdominal infection (i.e., appendicitis)
Intrascrotal abscess requires surgical drainage

Imaging

US is the modality of choice
Complex-appearing fluid around the testicle
Scrotal skin thickening with hyperemia
Evidence of causes such as epididymitis or others
Based on imaging, it is difficult to distinguish pyocele from hematocele

References

1. Siegel MJ. Pediatric Sonography, 2010.

2. Resnick MI, Novick AC. Urology Secrets, 3rd ed, 2003.

Renal Scarring

rathachai@gmail.com — Mon, 21 Nov 2011 00:00:00 +0000

A longitudinal ultrasound image of the kidney shows a focal depression of the lower pole cortex (arrows) with focal parenchymal thinning and a caliceal stone (between calipers).

Facts:

Renal scar is a common incidental finding during imaging of the GU tract
It can occur both with and without episodes of infundibular obstruction
Reflux is considered a major contributor in development of non-obstructive scarring, particularly in children with vesicoureteric reflux (VUR)
In adults, renal scarring is more associated with renal stone disease, either with stone or history of stone

Imaging

Focal cortical thinning and depression of the cortex, overlying the pyramid on any imaging modalities (IVU, US, CT, MR)
Hyperechoic band is seen over the parenchymal thinning on US
Mimic = normal renal lobulation. Lobulation will span the pyramids with echogenic lobular junctions into renal columns

Reference:

Newhouse JH, Amis, Jr, ES. The relationship between renal scarring and stone disease. AJR 1988; 151:1153-1156.

Parotid Mass

rathachai@gmail.com — Fri, 11 Nov 2011 00:00:00 +0000

US and CT images of a solid mass in the right parotid gland of an 82-year-old woman who had a painless neck mass for a year.

Facts: Parotid Mass Workup

Long list of differential possibilities: neoplastic vs. non-neoplastic conditions
Most helpful test = fine needle aspiration biopsy (accuracy 85-90% in experienced cytologist's hands)
CT/MRI helpful for treatment planning to determine disease extent and whether facial nerve would need to be sacrificed during surgery

Differential Diagnosis

Can be limited by patient's demographic information: age and immune status
Facial nerve palsy implies malignancy and poor prognosis
Children: hemangioma, lymphangioma, first branchial cleft cyst, pleomorphic adenoma
AIDS: benign lymphoepithelial cysts, infection, lymphoma
Adults: pleomorphic adenoma (>80%), Warthin tumor, malignant tumor (mucoepidermoid, adenoid cystic carcinoma), metastasis, lymphoma
Other nonneoplastic parotid masses: reactive adenopathy, cystic lymphoid hyperplasia, sarcoidosis

Our case: Warthin tumor confirmed by biopsy

References:

1. Steward M, Selesnick SH. Differential Diagnosis in Otolaryngology: Head and Neck Surgery

2. Castillo M. Neuroradiology Companion: methods, guidelines, and imaging fundamentals, 3rd ed, 2006

Unilateral Diaphragmatic Elevation

rathachai@gmail.com — Tue, 01 Nov 2011 00:00:00 +0000

An AP chest radiograph shows elevation of the right hemidiaphragm.

Unilateral Diaphragmatic Elevation: Differentials

Lung/pleural disease: Pneumonectomy, lobectomy, pleurisy, subpulmonic effusion
Diaphragm disease: Phrenic nerve palsy / eventration
Abdominal disease: Hepatomegaly / hepatic mass / abdominal neoplasm / distended stomach

US and CT images demonstrate a very large cyst in the right lobe liver as a cause of elevated right hemidiaphragm.

AFP-Negative Hepatocellular Carcinoma

rathachai@gmail.com — Fri, 21 Oct 2011 00:00:00 +0000

An US image of the liver shows a 2 cm solid nodule in a cirrhotic liver.

CT images of the liver in arterial and portovenous phases show arterial contrast enhancement with rapid washout of the nodule.

Facts: Serum AFP & Hepatocellular Carcinoma (HCC)

First detection of AFP in serum of HCC patients in 1970s
Currently, it is the only widely used serologic marker for diagnosing HCC. Additional useful markers in use are AFP-L3 and DCP
Normal range 10-20 ng/mL
AFP greater than 400 ng/mL generally considered a point of discriminating HCC from other chronic liver disease
Problem: about 60% of patients with HCC have AFP below 200, up to 20% have normal AFP (AFP-negative HCC; AFP below 20)

Clinical Features of AFP-negative HCC

Less likely to be hepatitis B positive
Tend to have a lower level of ratio of serum glutamic oxaloacetic transaminase (AST)/pyruvic transaminase (ALT)

References:

1. Law WY. Hepatocellular Carcinoma, 2007.

2. Nomura F, Ohnishi K, Tanabe Y. Clinical features and prognosis of hepatocellular carcinoma with reference to serum alpha-fetoprotein levels. Analysis of 606 patients. Cancer 1989;64:1700-1707.

Infected Second Branchial Cleft Cyst

rathachai@gmail.com — Tue, 11 Oct 2011 00:00:00 +0000

Axial CT image of the neck in a 2-year-old boy shows a cystic lesion in the right neck anterior to the sternocleidomastoid muscle, lateral to the carotid space. There is wall enhancement and nearby fascial thickening and subcutaneous fat stranding.

Facts: Branchial Cleft Cyst

Type II = most common (92-99% of all branchial cleft cysts)
Anywhere along anterior aspect of sternocleidomastoid muscle, lateral to carotid sheath to parapharyngeal space at the level of palatine tonsil
CT: fluid density unless infected or hemorrhagic
MRI: T1 hypointense, T2 hyperintense (unless infected or hemorrhagic)
Can be associated with fistula or sinus tract

Other Things To Consider: Necrotic lymph node/metastasis, dermoid, abscess, laryngocele, ectopic thymic cyst

What Surgeons Want To Know

Infection? May need surgery if at risk of septicemia or abscess
Mass effects? Compression of esophagus, airways
Neoplasm?
Treatment of infected branchial cleft cyst is different from simple abscess. In the former, I&D alone is not adequate but the entire cyst and its tract must be removed to prevent recurrence. Therefore, it is important that accurate diagnosis is made preoperatively.

Our case: infected second branchial cleft cyst

Reference:

1. Bailey BJ, Calhoun KH. Atlas of Head & Neck Surgery-Otolaryngology, 2001.

2. Lin EC, Escott EJ, et al. Practical Differential Diagnosis for CT and MRI, 2008.

Intussusception Reduction

rathachai@gmail.com — Sat, 01 Oct 2011 00:00:00 +0000

A "scout" radiograph before intussusception reduction procedure shows a soft tissue mass (arrows) in the right upper quadrant representing the intussusception. There is no free air.

Contrast enema for reduction shows the intussusception (arrows) in the right upper quadrant. It was successfully reduced.

Facts

Image-guided liquid or air reduction of intussusception is the treatment of choice
Contraindications for image-guided reduction = peritonitis, free intraperitoneal air due to perforation, in shock or sepsis
Choice between air, liquid, contrast enema reduction of intussusception depends on radiologist experience and local preference/practice. Most radiologists prefer to use air and it is now generally accepted as the technique of choice
Air pressure: between 80 and 120 mmHg
Contrast: bag positioned approximately between 3 ft and 6 ft above the patient
Reduction rate between 80% to 95%

Preparation for Reduction

Notify the referring physician and surgeon
Patient must be stable, well-hydrated and has no evidence of peritonitis
IV line in place
A large-bore needle at hand (if you use air reduction)

Complications

Perforation rates with air enema less than 1%
Recurrence 10% of cases

Reference:

1. Daldrup-Link HE, Gooding CA. Essentials of Pediatric Radiology: A Multimodality Approach, 2010.

2. Hodler J, Von Schulthess GK, Zollikofer CL. Diseases of the Abdomen and Pelvis 2010-2013: Diagnostic Imaging and Interventional Techniques, 2010.

Intussusception: Ultrasound

rathachai@gmail.com — Wed, 21 Sep 2011 00:00:00 +0000

A longitudinal US image shows a "pseudokidney" sign of intussusception (arrows). Arrowheads point to enlarged mesenteric lymph nodes within the intussusceptum.

A transverse US image shows a "target" sign with a hypoechoic ring of the intussuscepiens surrouning the central echogenic area of intussusceptum. Arrowheads point to enlarged nodes.

Facts

A segment of bowel (intussusceptum) prolapses into a more distal bowel segment (intussuscepiens)
Most frequently seen in the first two years of life but can be seen up to 4 years. If older child has intussusception, looks for a lead point such as polyp, Meckel diverticulum, lymphoma, duplication cyst.
Classic triad: colicky pain, vomiting and bloody (red currant jelly) stools (seen in less than 25% of cases)
X-ray is positive in only 50% of cases, and is not reliable in diagnosing this condition

Ultrasound Findings

Modality of choice to diagnose intussusception
"Target" sign = hypoechoic ring with an echogenic center on transverse US image
"Pseudokidney" sign = hypoechoic bowell wall extending along a hyperechoic mucosa
Helpful in searching for a lead point. US can provide a specific diagnosis in one-third of these cases.

Reference:

1. Daldrup-Link HE, Gooding CA. Essentials of Pediatric Radiology: A Multimodality Approach, 2010.

2. Hodler J, Von Schulthess GK, Zollikofer CL. Diseases of the Abdomen and Pelvis 2010-2013: Diagnostic Imaging and Interventional Techniques, 2010.

Tension Pneumothorax

rathachai@gmail.com — Sun, 11 Sep 2011 00:00:00 +0000

Chest radiograph shows a very large left pneumothorax (stars) causing mass effect to the mediastinum (shifting, arrows), deep costophrenic sulcus and collapsed left lung.

Facts

One-way valve effect causing continuous air collection within pleural space resulting in collapse of the lung on the affected side and compression of opposite lung
Poor lung compliance and increased airway pressure leads to ineffective gas exchange
Mass effect on mediastinal structures cause decreased venous return and decreased cardiac output
Symptoms and signs: chest pain, dyspnea, respiratory distress, tachypnea, dyspnea, cyanosis, elevated jugular venous pressure, absent breath sounds, tracheal deviation and hemodynamic compromise
This is a clinical diagnosis and confirmation with radiography is not recommended. Needle decompression should be immediately performed

Imaging

Again, this is a clinical diagnosis. Yet imaging may be performed and shows large pneumothorax, mediastinal shifting, flat hemidiaphragm

Reference:

Greenberg MI. Greenberg's Text-atlas of Emergency Medicine, 2005.

Fracture of the Lateral Process of Talus

rathachai@gmail.com — Thu, 01 Sep 2011 00:00:00 +0000

AP view of the foot shows a small avulsion fracture (arrow) of the lateral process of the talus.

Facts: Lateral Process of Talus

Lateral process is a broad-based, wedge-shaped prominence of the lateral talar body that articulates with the fibula and posterior facet of talus
Anchor point for lateral talocalcaneal, anterior and posterior talofibular ligaments

Facts: Fracture of the Lateral Process of Talus

Axial loading with elements of dorsiflexion and eversion or external rotation
High incidence among snowboarders, sometimes called "snowboarder fracture"
Can be difficult to diagnose clinically, easily confused with ankle sprain
Pain localized anteroinferior to the distal end of fibula

Imaging

Important to look specifically at this area in patients presenting with lateral ankle pain following trauma
Small, nondisplaced fracture can be overlooked. CT may be warranted if suspicion persists in a normal-looking x-ray series
Hawkins classified this fracture into 3 types: 1) large single fragment, 2) large comminuted fragment, 3) small, extra-articular fragment

Reference:

Browner BD, Levine AM, Jupiter JB, et al. Skeletal Trauma: Basic Science, Management, and Reconstruction, 2009.

Ileal Diverticulitis

rathachai@gmail.com — Sun, 21 Aug 2011 00:00:00 +0000

Axial CT image shows an ileal diverticulum (arrow) with surrounding inflammation (arrowheads). Thin arrow = normal appendix.

Sagittal CT image again confirms the presence of an inflamed ileal diverticulum. Note a normal cecum.

Facts

Two percents of population have small-bowel diverticula
These can be congenital or acquired.
Acquired diverticula are common in jejunum and terminal ileum. They are mucosal herniation along the mesenteric border.
About 6-10% of patients with small-bowel diverticula develop complications (-itis, hemorrhage, obstruction, intussusception)

Imaging

CT can show inflammatory change around the diverticulum with mural thickening of the adjacent bowel loops. The appendix and cecum are normal.

Reference:

Gourtsoyiannis NC. Radiologic Imaging of the Small Intestine, 2002.

Kaposi's Sarcoma

rathachai@gmail.com — Thu, 11 Aug 2011 00:00:00 +0000

Axial CT image shows perihilar peribronchovascular thickening (arrows) and several small ill-defined nodules in the peribronchovascular distribution.

Axial CT image shows patchy groundglass opacities and consolidation in the right middle and lower lobes.

Facts

Multicentric neoplasm occuring in three distinct clinical settings: classic (middle-aged adults or elderly men with indolent course), endemic (native populations of equatorial Africans) and disseminated forms (AIDS and immunosuppressed recipients of organ transplants)
Associated with human herpesvirus type 8
Cutaneous manifestations usually precede visceral disease
Respiratory disease is a late manifestation of the disease, it can involve trachea, bronchial tree, pleura and lung parenchyma
Diagnosis of respiratory disease is often made presumptively based on clinical/imaging appearance and exclusion of other entities. Biopsy is most definitive.
Treatment of pulmonary disease almost always involves chemotherapy

Thoracic Imaging Findings

Two patterns: interstitial and nodular
Interstitial pattern -- septal lines, localized/focal consolidations, perihilar distribution, "flame-shaped" opacities
Nodular pattern -- ill-defined nodules of various sizes that may coalesce into areas of patchy consolidation
Up to 60% has pleural effusion
Up to 16% has hilar/mediastinal lymphadenopathy

Our case: Kaposi's sarcoma, biopsy-proven

References:

Humes HD. Kelley's Essentials of Internal Medicine, 2001.

Parsons PE, Heffner JE. Pulmonary/reespiratory Therapy Secrets, 2002.

Sialolithiasis

rathachai@gmail.com — Sun, 31 Jul 2011 00:00:00 +0000

Lateral radiograph of the neck shows a very large, well-defined calcification with layered appearance overlying the inferior aspect of the mandible.

Axial CT image confirms the location of the stone in the left submandibular gland. Dilated submandibular duct is also present (not shown).

Facts:

Stone disease (sialolithiasis) is the most common disease of the salivary gland; male more common than female; very rare in children
Submandibular gland is the most common location of stones in the salivary gland (80% of all)
Stone disease is a common cause of acute and chronic salivary gland infections
Stones consist of mainly calcium phosphate

Imaging:

20% of submandibular stones, and 40% of parotid stones are non-opaque
Occlusal radiographs useful in showing radiopaque stones
Sialography is useful in patients suspected of having non-opaque stones but it is contraindicated in acute infection
CT and ultrasound can show stones with high accuracy
Gland may be diffusely or focally enlarged with a stone in the duct

References:

Siddiqui SJ. Sialolithiasis: an unusually large submandibular salivary stone. Br Dent J 2002;193:89-91.
Yousem DM, et al. Major salivary gland imaging. Radiology 2000;216:19-29.

Nephrogenic Systemic Fibrosis Disappeared After Restrictive Use of Gadolinium?

rathachai@gmail.com — Thu, 21 Jul 2011 00:00:00 +0000

According to a large (50 000+) retrospective cohort of patients who underwent contrast-enhanced MR examinations at a single academic institution pre- and post-adoption of strict gadolinium guidelines:-

No new cases of nephrogenic systemic fibrosis (NSF) were diagnosed
During the pre-guidelines adoption and transitional period, the incidence of NSF was 3 cases per 10,000 contrast-enhanced MRI
After the adoption of guidelines, the incidence was 0 per all examinations

The Guidelines for Imaging Adult Patients

Based on renal disease severity
eGFR 60 or greater - GBCA can be administered as indicated
eGFR 30-59 - weight-based dose of GBCA (0.2 mL/kg) can be administered with maximal dose of 20 mL allowed within 24 hours
eGFR less than 30 - GBCA cannot be administered except in cases of medical necessity; informed consent required; nephrology consultation required; hemodialysis should be considered
Very rarely that any patients with eGFR less than 30 would get contrast-enhanced MR exams (36 in 52 954 exams; 0.07%)

eGFR = estimated glomerular filtration rate; GBCA = gadolinium-based contrast agent

Reference:

Wang Y, Alkasab TK, Narin O, et al. Incidence of nephrogenic systemic fibrosis after adoption of restrictive gadolinium-based contrast agent guidelines. Radiology 2011; 260:105-111.

The Price of Being a Doctor

rathachai@gmail.com — Fri, 15 Jul 2011 00:00:00 +0000

How one patient makes a doctor question his decision to be a physician, while another does the opposite? Follow the link to the Insights on Residency Training blog by the Journal Watch.

Predictors of Cervical Spine Fractures and Fracture Risk

rathachai@gmail.com — Mon, 11 Jul 2011 00:00:00 +0000

Flow diagram (originally published by Blackmore CC, et al, Radiology 1999) demonstrating a prediction rule for determination of risk of cervical spine fracture in blunt trauma patients. Percentages indicate the risk of fracture for each group with 95% CIs. Area under the ROC curve = 0.87

Facts:

Three common options exist to "clear" cervical spine in trauma patients: clinical evaluation, radiography or CT
Canadian C-spine Rule (CCR) or NEXUS criteria are generally used by emergency physicians and trauma surgeons to determine which patients require imaging clearance
Among patients who, based on CCR or NEXUS, need imaging clearance: an issue exists whether to choose x-ray vs. CT
In general, CT is preferred for patients with moderate or high likelihood of having C-spine injury given its higher accuracy, cost-effectiveness and ease of performance. However, C-spine CT has not been tested as cost-effective among patients with low likelihood of C-spine injury - practice has been different from one place to another

According to Blackmore CC, et al

We can stratify patients into groups of different fracture probabilities by using 4 predictors: severe head injury, high-energy cause, age and focal neurologic deficit
Definition of severe head injury = intracranial hematoma, brain contusion, skull fracture or unconsciousness
Definition of high-energy cause = high-speed MVC (greater than 30 mph), pedestrian struck by car
Definition of moderate-energy cause = low-speed MVC, MVC at unknown speed, bicycle accident, motorcycle accident or fall
Definition of focal deficit = those that could be in a spinal cord or spinal nerve distribution

Reference:

Blackmore CC, Emerson SS, Mann FA, Koepsell TD. Cervical spine imaging in patients with trauma: determination of fracture risk to optimize use. Radiology 1999; 211:759-765.

Child Abuse

rathachai@gmail.com — Wed, 06 Jul 2011 00:00:00 +0000

A frontal radiograph of the femur demonstrates classic metaphyseal lesions of the distal femur and proximal tibia medially (arrows)

Facts:

The two most common injuries in child abuse = soft tissue injuries and fractures
Failure to recognize child abuse may result in the child's return to hostile environment, leading to repeated injuries and possible death
Highly specific fractures = rib, spinous process, and sternal fractures and classic metaphyseal lesions
High suspicion = multiple fractures of differing ages

The Skeletal Survey

To evaluate children less than 2 years old for signs of physical abuse
American College of Radiology (ACR) recommends a single frontal view of each region of the appendicular skeleton (arms, forearms, thighs, legs, hands and feet), frontal and lateral views of the axial skeleton (skull, C-spine, LS spine and thorax) and a frontal view of the pelvis <=== these are a minimum of 20 radiographs
In a recent report of 930 abused children, prevalence of fractures was 34%. Skeletal survey added value in 13% of cases in which new fractures were discovered only at skeletal survey but not on prior imaging. Most fractures occur in long bones, ribs and skull. Pelvis, spine, hands and feet were much less common to be fractured (only 1% of all cases, which also had other fractures diagnostic of abuse). The authors called for eliminating x-rays of the pelvis, spine, hands and feet from skeletal survey performed for suspected child abuse

Reference:

Karmazyn B, Lewis ME, Jennings SG, et al. Prevalence of uncommon fractures on skeletal surveys performed to evaluate for suspected abuse in 930 children: should practice guidelines change? AJR 2011; 197:W159-W163.

Obstructing Ureteric Stone on Ultrasound

rathachai@gmail.com — Fri, 01 Jul 2011 00:00:00 +0000

Figure 1: A gray-scale ultrasound image of the right kidney shows right hydronephrosis and hydropelvis.

Figure 2: The scan in the right pelvis demonstrates an echogenic focus (arrow) with posterior acoustic shadowing (arrowheads) at the site where the ureter abruptly changes its caliber.

Facts:

Imaging in patients presenting with renal colic is performed to 1) confirm the suspected renal colic, 2) diagnose cause and level of obstruction, 3) detect or rule out complications of renal colic (obstruction, infection), 4) detect alternative diagnoses
Non-contrast CT is current gold standard for diagnosis of urinary tract stone disease
Ultrasound may be an initial imaging done although its sensitivity is limited (37% - 64%) for detecting renal calculus (lower for ureteric calculus) and acute obstruction (74% - 85%)

Imaging Appearance

Stone (brightly echogenic focus with posterior acoustic shadowing). For renal stone less than 5 mm, ultrasound is of limited accuracy. Ureteric stone is uncommonly appreciated on US.
Hydronephrosis
Twinkling artifact behind the stone, and absent ureteral jet on color Doppler imaging

Reference:

Scott LM, Sawyers SR, Bokhari J, Hamper UM. Ultrasound evaluation of the acute abdomen. Ultrasound Clin 2007;2:493-523.

Cerebral Venous Sinus Thrombosis (CVST)

rathachai@gmail.com — Sun, 26 Jun 2011 00:00:00 +0000

Figure 1: Axial image of the brain shows ill-defined areas of hypoattenuation (stars) in bilateral frontal lobes involving both gray and white matter, in a nonarterial distribution.

Figure 2: A lateral view of CT venography shows occluded anterior 1/3 of the superior sagittal sinus (arrows).

Facts

0.5% of all strokes
Peak incidence in neonates and adults in third decade of life (female:male = 5:1.5)
Clinical presentation varies widely from relatively mild symptoms to devastating hemorrhage
Risk factors following Virchow's triad: blood stasis, changes in vessel wall, and changes in blood composition
Intravenous heparin and subcutaneous low-molecular-weight heparin are primary Rx for acute CVST. Hemorrhage does not preclude the diagnosis.
Patient prognosis depends on location of CVST (best if in cortical vein, anterior superior sagittal sinus, isolated transverse and isolated sigmoid sinus) and extent of involvement (the more segments of veins involved, the greater complications)

Imaging

Infarction or hemorrhagic infarction in non-arterial distribution
Delta sign = filling defect (clot) surrounded by enhanced venous blood in the affected sinus and dural enhancement
MRI shows T1 hyperintensity and lack of flow void
Look for potential etiology (and vice versa): paranasal sinus and mastoid infection

References

1. Qureshi AI. Textbook of interventional neurology. 2011

2. Castillo M. Neuroradiology companion: methods, guidelines and imaging fundamentals. 2006

3. Zubkov AY, McBane RD, Brown D, Rabinstein AA. Brain lesions in cerebral venous sinus thrombosis. Stroke 2009;40:1509

Tibial Plateau Fracture

rathachai@gmail.com — Wed, 25 May 2011 00:00:00 +0000

An AP knee radiograph shows a fracture of the lateral tibial plateau (arrows) in an osteopenic patient who had a recent trauma.

Facts

Fractures involving the articular surface of the proximal tibia. This is a diverse group of fractures, a spectrum of different severity of injuries
Most common mechanism of injury is fall with knee forced into valgus or varus
Imaging performed to locate the fracture, identify fracture pattern and degrees of displacement
Most common location = lateral tibial plateau
Aim of surgical treatment is to restore or preserve limb alignment

Imaging

Usually AP and lateral views of the knee show the fracture but bilateral oblique views are also recommended since many subtle joint impaction or fracture lines are not visible on the two views.
CT with reformations is a study of choice to delineate the extent, orientation of condyle, location and depth of articular comminution and impaction
Schatzker classification divides tibial plateau fractures into 6 types: lateral plateau without depression, lateral plateau with depression, lateral or central plateau compression, medial plateau, bicondylar plateau, plateau fracture with diaphyseal discontinuity.
Based on the classification, the management is different. The first three: repair the articular cartilage. The latter three: treatment depends on location of soft tissue injury.

Reference:

Markhardt BK, Gross JM, Monu J. Schatzer classification of tibial plateau fractures: use of CT and MR imaging improves assessment. RadioGraphics 2009

Acute Sinusitis

rathachai@gmail.com — Tue, 10 May 2011 00:00:00 +0000

Water's view radiograph of the paranasal sinus shows an air fluid level in the left maxillary sinus (arrows) of a 56-year-old man.

Facts:

Very common disease encountered by primary care physicians.
Diagnostic imaging is generally used in cases of recurrent or complicated sinus disease.
Plain radiography has a limited role in management of sinusitis

Imaging

Mucosal thickening, air-fluid levels, complete opacification of the involved sinus
Mucosal thickening seen in more than 90% of sinusitis case, but very nonspecific
More specific = air-fluid levels and complete opacification -- but seen in only 60% of cases
Interpretation can vary widely among observers, with a high rate of false-negative results
Radiography is not useful in patients younger than 3 years because of poorly developed sinuses
Because clinical judgment is sufficient to diagnose sinusitis in majority of cases, and empiric treatments are inexpensive and safe --- x-ray should be reserved for patients with persistent symptoms despite appropriate treatment.

Reference:

Okuyemi KS, Tsue TT. Radiologic imaging in the management of sinusitis. Am Fam Physician 2002; 15;66:1882-1887