The diagnosis of acute deep venous thrombosis: noninvasive and radioisotopic techniques

Sonographic assessment of traumatic injury. Future developments

In all its forms and applications, sonography plays a significant role in the management of injured patients, from the emergency department to beyond hospital discharge. The use of new and existing sonographic technology will increase because sonographic imaging and measurements are generally less invasive; are inexpensive; use no ionizing radiation; and are portable, repeatable, and, in many instances, as accurate as the so-called "contemporary gold standards." The training and credentialing of physicians in sonography is in evolution and will be an increasingly important issue with more widespread use and broader applications. The future of sonography in trauma care in the next millennium is bright, and surgeons and surgical residents are encouraged to gain proficiency and learn about this new surgical frontier as it evolves.

Vascular ultrasound

Surgeon-interpreted diagnostic ultrasound has become the preferred screening test and often the definitive test for the diagnosis of arterial stenosis, aneurysm, and venous thrombosis. As a modality for surveillance, its noninvasive quality makes it particularly appealing as the test of choice to screen patients for abdominal aortic aneurysms or to perform follow-up examinations on those patients with a carotid endartectomy or in situ bypass grafts. The increasing reliance on intraoperative duplex imaging of vascular procedures demands that the surgeon learn the skills to perform the studies without a technologist or radiologist to interpret the examination.

Diagnosis of acute lower limb deep venous thrombosis with ultrasound: trends and controversies

Acute deep venous thrombosis of the lower limb is a common and threatening condition whose clinical diagnosis is known to be unreliable. Sonography has gradually superseded venography as the primary diagnostic procedure. A review of the medical literature shows that sonography offers a high level of sensitivity and specificity in symptomatic patients but suffers from a lack of sensitivity at the calf level and in asymptomatic patients. Technologic progress, as well as increased operator experience, may improve sensitivity. Nevertheless, several critical issues remain unresolved, such as the significance of free-floating thrombi, the usefulness of calf and bilateral examination, the criteria that are essential to the diagnosis, the risk of compression sonography, and sonography's role in the direct detection of venous emboli.

The safety and pharmacokinetics in adult subjects of an intravenously administered 99mTc-labeled 17 amino acid peptide (CYT-379)

A phase I study was designed to evaluate the safety and pharmacokinetics of a novel platelet reactive peptide, peptide acetyl-SYGRGDVRGDFKCTCCA-amide (CYT-379), which binds to the fibrinogen receptor of activated platelets and also binds to 99mTc. Eleven subjects with suspected deep venous thrombosis had 0.1, 0.5 or 1.0 mg of the peptide infused intravenously. Pharmacokinetics were determined by assaying blood samples in 6 of the 11 subjects and by urine sampling in 5 of these 6 subjects. Plasma and whole blood time-activity curves demonstrated an initial fast component with half-time clearance of 0.2 +/- 0.01 and 0.2 +/- 0.02 h and a slow component with half-time clearance of 2.8 +/- 0.3 and 2.7 +/- 0.2 h (mean +/- SEM for plasma and whole blood, respectively). Urine clearance was 22.6 +/- 3.3 and 10.8 +/- 1.6 mL/min when normalized to body surface area. The cumulative excretion of 99mTc-CYT-379 in the urine was 16.6 +/- 3.6, 45.6 +/- 16.9 and 45.6 +/- 1.8% of the administered dose over 0-2, 0-12 and 0-24 h after radiopharmaceutical injection, respectively. Images obtained in 11 subjects immediately, at 1-2, and 4-6 h after injection were evaluated for abnormalities and were compared with duplex Doppler ultrasonography. 99mTc-CYT-379 images were positive in only 3 of 7 subjects who had a positive duplex Doppler examination in at least one lower extremity. One subject with negative duplex Doppler had also negative 99mTc-CYT-379 scintigraphy. One subject with negative scintigraphy and two other subjects with positive scintigraphy had no other imaging studies of the deep venous system performed. No adverse reactions were observed during or after the infusion of 99mTc-CYT-379. 99mTc-CYT-379 appears to be a safe radiopharmaceutical and demonstrates rapid clearance from plasma in human subjects.

[Venous echo Doppler: a future standard test in the diagnosis of thrombosis of the lower limbs?]

Duplex ultrasound imaging provides both an ultrasound picture of the tissue being explored and the sound of the flow speed in a particular area. Colour Doppler imaging gives colour codes for the different flow rates. Venous pathology is always investigated, with ultrasound, on both sides, at the iliac and caval, femoral, and foreleg levels. For the latter, excellent equipment and patient position are required. Ultrasound criteria of deep venous thrombosis (DVT) are the incompressibility of the vein being investigated, and detection of the thrombosis with the ultrasound probe. Doppler criteria are asymmetric spontaneous flows, the loss of their respiratory rhythm, and the lack of flow induced by contraction of muscle. The colour Doppler draws provides the contours of a partial or floating thrombus. Compared with phlebography, ultrasound imaging has a sensitivity and specificity of 96%. Colour Doppler imaging is even more accurate: both sensitivity and specificity increase to 100%. The limitations of ultrasound are: its dependence on the investigator, the difficulty of making the diagnosis of recurring DVT when there already are previous sequellae, obesity, intra-abdominal gas, skin lesions or inflammatory oedema. Phlebography remains necessary in 5% of cases. The advantages of this technique are its non invasiveness, excellent diagnostic performance, low cost, and the possibility of diagnosing another cause, whether responsible for the clinical signs or not. It is indicated for the diagnosis of DVT, routine screening in patients at risk, and the early and late follow-up of patients. Today, ultrasound imaging should always be carried out before other investigations.(ABSTRACT TRUNCATED AT 250 WORDS)

Magnetic resonance imaging for calf deep venous thrombophlebitis

STUDY OBJECTIVE

To compare magnetic resonance imaging (MRI) of the calf with venography for patients with suspected calf deep venous thrombophlebitis (DVT).

DESIGN

Ten consecutive adult patients with suspected calf DVT received venography and, within 48 hours, MRI scans. The tests were reviewed blindly by two radiologists, and results of the tests were compared.

SETTING

The emergency department of a large teaching hospital with an annual census of 60,000 patients.

MAIN RESULTS

All patients with negative venograms had no suggestion of DVT on MRI scan. Two of these patients had other significant demonstrable abnormalities. Four of the five patients with positive venograms had positive calf MRI scans. One patient with a venogram that was difficult to interpret had no DVT on MRI. A thigh DVT was seen on his venogram and was suggested by MRI findings.

CONCLUSION

MRI may replace ascending venography as the standard for diagnosis of calf DVT.