Diagnostic management of acute upper extremity thrombosis with Magnetic Resonance Direct Thrombus Imaging

The clinical diagnosis of upper extremity thrombosis (UE-DVT) alone is
inaccurate. Therefore accurate objective imaging is required to avoid
incorrectly concluding that thrombosis is present or absent placing the patient
at risk for a pulmonary embolism at the one hand or a -potentially fatal-
bleeding at the other hand.
Although a clinical algorithm has been created, the diagnosis of UE-DVT poses a
clinical challenge. Contrast venography is considered the reference standard
for diagnosing UE-DVT. However this technique is invasive and requires
radiation exposure. Furthermore in 18% of the patients contrast venography
could not be performed.
Ultrasonography is noninvasive and does not expose the patients to radiation
and intravenous contrast. Compression ultrasonography (CUS) as diagnostic
modality for suspected UE-DVT is reliable in anatomic places where compression
is possible with a sensitivity of 96% and specificity of 94%. However if the
thrombosis is more centrally located, the accuracy of CUS is poor due to
overlying anatomical structures which limit the possibility of applying
compression. Doppler ultrasonography could be used in these area, but
visualization of the thrombus is often difficult. Therefore contrast venography
is still recommended as diagnostic modality in these patients. CT-venography
and MR-venography may serve as alternative modalities; however CT still
requires contrast medium and exposes the patient to radiation. Furthermore only
limited studies have been performed with the use of MR venography and the
studies which evaluated the use of MR venography in suspected UE-DVT were
gadolinium enhanced techniques.

Magnetic Resonance Direct Thrombus Imaging (MRDTI) has been shown a highly
accurate diagnostic method for a first deep vein thrombosis of the legs.5,6 The
method is based on measurement of the T1 signal which shortens as a result of
the formation of methemoglobin in a fresh thrombus. This technique does not
require the administration of gadolinium and the acquisition time is short,
making this a patient friendly technique. The sensitivity was 97% and
specificity 1000% for diagnosis of DVT in the legs. However studies have never
assessed the reliability of MRDTI in patients with a suspected UE-DVT.

Before embarking on a study using MRDTI as sole test to manage clinically
suspected UE-DVT, we need to perform a study to determine whether the test has
the potential to be useful in patients with suspected UE-DVT. This study has
the objective to estimate the sensitivity of MRDTI by examining patients with a
clinically suspected UE-DVT. We reason that since MRDTI has already been
sensitive for DVT of the legs, it should be sensitive for the arms too, since
formation of methemoglobin in a thrombus is common to both conditions and
normal MRDTI should rule out UE-DVT. On the other hand, if there were few false
positive results in patients with definitively ruled out UE-DVT by contrast
venography an abnormal result would be diagnostic of UE-DVT.

This study is a prospective diagnostic study in patients with a suspected acute
arm vein thrombosis.
All patients with a suspected UE-DVT are eligible for inclusion. The diagnosis
(recurrent) UE-DVT has to be confirmed by an abnormal CUS, contrast venography
or CT venography result and exclusion of (recurrent) UE-DVT needs to be
confirmed by a normal contrast venography or CT venography result. In case
contrast venography is not feasible patients receive serial CUS after 1 week.
All included patients receive a MRDTI examination within 48 hours after the
initial diagnostic test.
Furthermore all patients who have UE-DVT excluded receive a phone call after 3
months, in which they are asked whether they had thrombosis diagnosed during
the follow-up and visited the hospital because of acute complaints of
thrombosis. Finally it will be recorded whether patients died during the
follow-up period.

Patients receive as extra examination the MRI. There are no known side-effects
of MRI examination.