May 29, 2009

Slideshow: Imaging Acute Abdomen (Part 1)

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May 26, 2009


Figure: Bone scan image shows diffuse increased bone uptake throughout the skeleton with relative absence of kidney uptake (arrows), consistent with "superscan". There are several focal areas of uptake in the ribs, skull (arrowhead), scapulae and extremities indicating metastatic disease in a 73-year-old man with prostate cancer. The patient had a right craniotomy defect seen as a photopenic region on the posterior view.

Superscan "High ratio of bone uptake relative to soft tissue uptake, absent or relatively decreased renal uptake, homogeneous uptake of axial skeleton"

Two Types of Super Scan
  1. Metabolic: homogeneous uptake, usually hot at the calvarium, uptake seen at the extremities
  2. Metastatic: heterogeneous, usually absent uptake at the calvarium (unless metastatic lesions), uptake at distal extremities usually not seen

Metastatic "Superscan"
  • Prostate cancer, breast cancer, lung cancer
  • RCC, lymphoma, bladder cancer
Morton K, et al. Diagnostic Imaging: Nuclear Medicine. Amirsys, Inc. 2007

May 20, 2009

Functioning Ovarian Tumors

Figure: Coronal reformatted CT image shows a very large mixed cystic/solid mass in the abdomen/pelvis of a 25-year-old woman presenting with hirsutism. On CT, her normal right ovary is not visualized. The left ovary is normal.

  • Several ovarian tumors and tumorlike conditions can produce estrogen or androgen, resulting in signs and symptoms of hyperestrogenism or hyperandrogenism
  • Enlarged uterus with thick endometrium can be seen on imaging in patients with hyperestrogenism

Tumors/tumorlike conditions producing hyperandrogenism
  • Sertoli-Leydig cell tumor
  • Leydig cell tumor
  • Gynandoblastoma
  • Germ cell tumor (carcinoid)
  • Brenner tumor
  • Tumorlike conditions (polycystic ovary syndrome, stromal hyperplasia, stromal hyperthecosis, hyperreactio luteinalis, pregnant luteoma)
Tumors producing hyperestrogenism
  • Granulosa cell tumor
  • Thecoma
  • Serous epithelial tumor
  • Mucinous epithelial tumor
  • Endometrioid tumor
Tumors that can produce either estrogen or androgen
  • Metastatic tumor
  • Stromal luteoma
  • Sclerosing stromal tumor
Our case: Carcinoid tumor of the right ovary.


Tanaka YO, Tsunoda H, Kitagawa Y, et al. Functioning ovarian tumors: direct and indirect findings at MR imaging. Radiographics 2004;24:S147-S166.

May 17, 2009

Ewing Sarcoma of the Pelvis

Figures 1 & 2: Coronal reformatted CT images of the pelvis of a 16-year-old man show a large heterogeneous soft tissue mass (arrows) involving the right iliac bone. The mass is enhanced and contains ring and arc calcifications. Note lytic lesions in the lumbar vertebral body (arrowhead).
Figure 3: Anterior bone scan image of the pelvis shows focal increased uptake in the right iliac bone and L4 vertebral body, corresponding with findings on the CT scan.

  • First described by Ewing in 1921
  • Family of small round cell neoplasms including: 'classic' Ewing sarcoma of bone, extraskeletal Ewing sarcoma, small cell tumor of thoracopulmonary region (Askin tumor), and soft tissue-based primitive neuroectodermal tumors (PNET).
  • Currently believed to be due to spontaneous genetic transolocation
  • Second most common bone cancer in adolescents and young adults (after osteosarcoma)
  • 5-20 years old, male slightly more than female
  • Whites much more common than Asians or Africans

Imaging Appearance
  • Permeative lytic lesion with soft tissue components
  • Ring and arc calcifications (chondroid matrix)
  • Codman triangle or onion multi-layered periosteal reaction
  • Common locations: pelvic bones (26%), femur (20%), tibia/fibula (18%), chest wall (16%)
  • In long bone, diaphysis > metaphysis
  • Increased uptake on bone scan
  • Aim to distinguish localized disease from metastatic disease
  • MRI +/- CT of the lesion
  • Chest CT to look for pulmonary metastasis
  • Whole body bone scan or PET
  • Bone marrow biopsy or MRI of the spine
  • Tumor at nonaxial skeleton primary site, age <>
Our case: Ewing sarcoma with bone metastases

Ludwig JA. Ewing sarcoma: historical perspectives, current state-of-the-art, and opportunities for targeted therapy in the future. Curr Opin Oncol 2008; 20:412-418.

May 14, 2009

Testicular Germ-cell Tumor

Figure 1 and 2: Gray-scale longitudinal (1) and Doppler flow transverse ultrasound images (2) of the testicle show an ill-defined hypoechoic, solid mass within the testicle (intratesticular mass). There are scattered microcalcifications throughout the testicle.

Histologic Classification of Primary Testicular Neoplasms
1. Germ-cell tumors (95%)
Embryonal carcinoma
Yolk-sac tumor (endodermal sinus tumor)
2. Others (5%)
Sex-cord stromal tumors: Sertoli-cell, Leydig-cell, Granulosa-cell
Both germ-cell and gonadal stromal elements: Gonadoblastoma
Adnexal and paratesticular tumors

Germ-Cell Tumor
  • Originates from primordial germ cells
  • More common in Whites
  • Predisposing factor = cryptorchidism
  • Two major types: seminoma or non-seminoma
  • Nonseminoma tumors are clinically more aggressive. Therefore, if the pathology shows mixed tumor, treatment will follow nonseminoma.
  • Seminoma is diagnosed only if histology shows "pure seminoma" and serum alfa-phetoprotein (AFP) is normal
  • Classic but uncommon = painless testicular mass
  • Common = diffuse pain, swelling, hardness or a combination of these
Tumor Markers
  1. AFP: nonseminoma, specifically embryonal cell and yolk-sac tumors
  2. hCG: both seminoma and nonseminoma
  3. LDH: both seminoma and nonseminoma

Our case = Embryonal cell carcinoma.

Bosl GJ and Motzer RJ. Testicular germ-cell cancer. New Engl J Med 1997;337:242-254.

May 12, 2009

Prepare for the AOCR 2010

The Asian Oceanian Congress of Radiology (AOCR) is to be held in Taipei, Taiwan from March 20 to 23, 2010.

"AOCR 2010 will be featured with the main theme of this congress: Radiology – The Core of Healthcare. Recent progress in radiology will be highlighted in the whole scientific program. A large panel of experts, within or outside the Asian Oceanian region, will share their experiences and present their best in this congress. It will definitely provide the best atmosphere for discussing the groundbreaking researches and progresses in the field of radiology. We believe this congress will provide a good opportunity for all of us to update ourselves on the knowledge of radiology and to share clinical experiences as well as basic researches." - Organizer

Details of meeting can be found at

May 11, 2009

Inferior Vena Cava (IVC) Filter: Indications

Figure 1 and 2: Frontal view of the scout angiographic image (1) and axial CT image (2) show an IVC filter (arrows).

IVC Filter
  • Does prevent pulmonary embolus (PE) by trapping venous emboli
  • Does not prevent new thrombus formation
  • Does not promote lysis of preexisting thrombus
Absolute Indications
  1. Documented deep vein thrombosis (DVT) and/or PE but cannot be anticoagulated
  2. Documented progression of DVT or recurrent PE while anticoagulated
  3. Complication of anticoagulation that requires anticoagulants to be terminated
  4. Massive, life-threatening PE that requires thrombosis or surgical thrombectomy
  5. Recurrent PE due to failed existing IVC filter
Relative Indications
  1. Documented DVT and/or PE and limited cardiac or pulmonary reserve, poor compliance with medications, fall risk, inability to monitor
  2. Large burden of clot in extremity veins
  3. Patients with past history of DVT and/or PE that will undergo operation (i.e. knee replacement, craniotomy) with high-risk of postoperative DVT/PE
  4. Patients at high risk of developing DVT and/or PE (i.e. multiple trauma)
Kaufman JA. Vena Caval Filters. In: Kandarpa K and Aruny JE, eds. Handbook of interventional radiologic procedures. 3rd ed. 2002.

May 8, 2009

Complications of Radiofrequency Ablation of Liver Tumors: Hematoma

Figure 1: Axial CT image before radiofrequency ablation of a liver metastasis (star) is shown.
Figure 2: Axial CT image immediately after the RFA shows a small subcapsular hematoma anterior to the right hepatic lobe (arrows). Note hyperattenuation change at the tumor site (star), which is expected after the RFA.

Vascular complications of RFA
  1. Portal vein thrombosis (0.7%)
  2. Subcapsular hematoma (0.7%)
  3. Hepatic vein thrombosis
  4. Hepatic infarction
  • Thrombosis of vessel occurs as a result of 'heat-sink' effect to the flowing blood. Smaller caliber vessels are prone to thrombose due to thermal damage from RF ablation
  • On US, or CT, thrombosis is visualized as filling defects
  • Hepatic parenchyma may show segmental enhancement peripheral to the affected veins
  • Most thrombosis is self limited
  • Subcapsular hematoma usually is related to placement of electrodes or underlying coagulopathy.
Akahane M, Koga H, Kato N, et al. Complications of percutaneous radiofrequency ablation for hepatocellular carcinoma: imaging spectrum and management. Radiographics 2005; 25:S57-S68.

May 5, 2009

Suspected Pulmonary Embolism in Pregnant Patient (3)

Figure: Axial CT image of the chest (PE protocol) shows filling defects (arrows) in the subsegmental branches of bilateral lower lobe pulmonary arteries in a pregnant woman at her 7-week gestation.

Second-line Imaging Tests
CT Pulmonary Angiography
  • Now accepted standard for imaging diagnosis of PE
  • In pregnant women, number of nondiagnostic CTPA may be higher than in non-pregnant population given an increased circulatory volume and altered cardiac output
  • CT venography portion should be replaced with lower extremity ultrasound to reduce radiation exposure
  • Dose reduction methods include (but not limited to): decrease mA, KVP and Z-axis coverage

Lung Scintigraphy
  • Consider in patients with normal chest radiograph and no history of asthma or COPD
  • Consider in patients with contraindication for iodinated contrast agent ie severe allergic reaction, impaired renal function
  • Dose reduction methods include (but not limited to): elimination of ventilation scan if perfusion scan negative, decrease dose of perfusion scan by half
Other Imaging Options
  • MRI without gadolinium can be performed by true fast imaging with steady-state precession, but limited evaluation to first-order pulmonary arteries
  • Conventional angiography is reserved only for unstable patients needing mechanical clot lysis, or when other tests are nondiagnostic

Pahade JK, et al. Imaging pregnant patients with suspected pulmonary embolism: what the radiologist needs to know. Radiographics 2009; 10.1148/rg.293085226 (Published online before print on March 30, 2009)

May 1, 2009

Viral Pneumonia

Fig. 1: PA chest radiograph shows a right upper lobe nodule (red arrow) in a patient who was receiving chemotherapy for lymphoma.
Fig. 2: Axial CT image of the same patient confirmed a nodule in the right upper lobe (not shown) and additional subsegmental consolidataion in the left lower lobe (yellow arrow) and band opacity in the right lower lobe (arrowheads).

  • Various viruses can cause pneumonia in adults
  • Two clinical syndromes are 1) Atypical pneumonia in normal hosts, and 2) Viral pneumonia in immunocompromised hosts
  • Common organisms are different in these two clinical scenarios: in normal hosts - influenza viruses are most common; in immunocompromised hosts - CMV and herpesviruses are most common
  • Pathology of viral lower respiratory tract infection is prominent in epithelium and adjacent interstitial tissue, then pneumonia occurs when the changes involve the lung adjacent to terminal and respiratory bronchioles. Progressive disease manifests as diffuse alveolar damage.
  • In general, it is difficult to distinguish viral from bacterial pneumonia based on imaging because of overlapping of findings.

In normal hosts:
  • Influenza is most common cause of viral pneumonia
  • On radiographs, there is poorly defined, patchy airspace consolidation that rapidly becomes confluent
  • On CT, there is ground-glass opacities mixed with consolidation
  • Pleural effusion is rare
  • In a study of 8 hospitalized patients infected with Avian Influenza (H5N1), chest radiographs showed extensive opacities with segmental and multifocal distribution. Most opacities were in lung bases. No effusion or hilar lymphadenopathy.
In immunocompromised hosts:
  • Cytomegalovirus (CMV) and herpesvirus are most common
  • CMV is actually a member of herpesvirus family
  • On imaging, there is mixed interstitial and airspace opacity that could range from ground-glass opacity, consolidation, nodules, poorly defined centrilobular nodules, bronchial dilatation and septal thickening
Our case is a 50-year-old man, known lymphoma, who developed CMV pneumonia.

1. Kim EA, Lee KS, Primack SL, et al. Viral pneumonias in adults: radiologic and pathologic findings. Radiographics 2002;22:S137-S149.
2. Bay A, Etlik O, Oner AF, et al. Radiological and clinical course of pneumonia in patients with avian influenza H5N1. Eur J Radiol 2007;61:245-250.