Diffusion-weighted MRI: role in detecting abdominopelvic internal fistulas and sinus tracts

Purpose:

To retrospectively determine the incremental value of diffusion‐weighted MR‐imaging (DW‐MRI) to T2‐weighted (T2w) images in diagnosis of internal fistulas (IFs) and sinus tracts (STs).

Materials and Methods:

Fourteen patients with 25 IFs and STs arising from the small bowel ( 20 ), colon ( 4 ) and biliary tract ( 1 ) were included. Two independent observers reviewed T2w images, T2w+DW‐MRI images and T2w+contrast enhanced T1‐weighted (CE T1w) images at three sessions to detect IF/ST based on a confidence scale of five. Sensitivity and confidence score of each session was compared.

Results:

10/25 (40%) and 9/25 (36%) IFs and STs were detected on T2w images by observer 1 and 2, respectively. Both observers detected 19/25 (76%) and 24/25(96%) IFs and STs on T2w+DW‐MRI and T2w+CE T1w images, respectively. Detection rate and confidence score improved significantly by combining T2w images with DW‐MRI or CE T1w images (reader 1 + 2: P ≤ 0.01). There was no significant difference between the IF/ST detection rate of T2w+DW‐MRI and T2w+CE T1 image combinations. Confidence scores with T2w+CE T1w images were significantly greater than DW‐MRI+T2w images (reader 1:P = 0.01; reader 2: P = 0.03).

Conclusion:

DW‐MRI showed additional value to T2w imaging for diagnosis of IF and ST. DW‐MRI can be a useful adjunct, especially for patients with renal failure. J. Magn. Reson. Imaging 2012;35:125‐131. © 2011 Wiley Periodicals, Inc.     

Penetrating injuries of the neck and the increasing role of CTA

Vascular injuries of the neck are most frequently the result of penetrating trauma. Diagnostic evaluation of hemodynamically stable patients who have suffered penetrating neck wounds is challenging and remains controversial. In order to reduce morbidity and mortality, prompt diagnosis and subsequent treatment of these injuries is critical. Traditionally, these patients undergo direct contrast angiography. However, this technique has limitations including its invasive nature and potential complications. The use of routine screening angiography has also been questioned because of the low rate of positive examinations. More recently, helical and multislice CT angiography (CTA) has emerged as a fast, minimally invasive accurate study to evaluate penetrating neck injuries. CTA is not operator-dependent and the results can be reproduced easily by using established technical parameters. It is readily available in most centers and allows the simultaneous evaluation of the extravascular soft tissues and bones.     

Gastrocolic fistula due to adenocarcinoma of the colon: simulation of primary gastric leiomyosarcoma on CT

This article describes the CT findings in two patients with adenocarcinoma of the colon and gastrocolic fistula which simulated the classic appearance of gastric leiomyosarcoma on CT. The role of CT in the diagnosis of gastrocolic fistula is also discussed.     

The increasing role of quantification in clinical nuclear cardiology: The Emory approach

Single photon emission computed tomography (SPECT) myocardial perfusion imaging has attained widespread clinical acceptance as a standard of care for patients with known or suspected coronary artery disease. A significant contribution to this success has been the use of computer techniques to provide objective quantitative assessment in interpreting these studies. We have implemented the Emory Cardiac Toolbox (ECTb) as a pipeline to distribute the software tools that we and others have researched, developed, and validated to be clinically useful so that diagnosticians everywhere can benefit from our work. Our experience has demonstrated that integration of all software tools in a common platform is the optimal approach to promote both accuracy and efficiency. Important attributes of the ECTb approach are (1) our extensive number of normal perfusion databases for SPECT and positron emission tomography (PET) studies, each created with at least 150 patients: (2) our use of Fourier analysis of regional thickening to ensure proper temporal resolution and to allow accurate measurement of left ventricular function and dyssynchrony: (3) our development of PET tools to quantify myocardial hibernation and viability; (4) our development of 3-dimensional displays and the use of these displays as a platform for image fusion of perfusion and computed tomography angiography; and (5) the use of expert systems for decision support. ECTb is an important tool for extracting quantitative parameters from all types of cardiac radionuclide distributions. ECTb should continue to play an important role in establishing cardiac SPECT and PET for flow, function, metabolism, and innervation clinical applications.     

Marginal sinus arteriovenous fistulas mimicking carotid cavernous fistulas: diagnostic and therapeutic considerations

Marginal sinus fistulas (MSFs) are uncommon vascular anomalies. Occasionally, the dominant venous drainage is forced retrograde up the inferior petrosal sinus and into the cavernous sinus, causing chemosis, proptosis, and ocular hypertension, mimicking a carotid cavernous fistula. This atypical clinical presentation may lead to misdiagnosis and inappropriate hazardous treatment of an MSF. Identifying the site of the fistula and understanding the anatomy of the venous drainage are critical in providing appropriate, safe, and efficacious endovascular treatment.     

Endoanal MRI of perianal fistulas: the optimal imaging planes

Twenty consecutive patients with the clinical suspicion of a perianal fistula were studied to define the optimal and time-efficient imaging planes for endoanal MRI in the identification and classification of perianal fistulas. The duration of each part of the MR procedure was recorded in all patients. Off-axis axial (A), coronal (C), sagittal (S) and radial (R) T2-weighted sequences were performed in all patients. Sets of images and combinations of images (A; R; CS; AR; ACS; ARCS) without patient data were reviewed in masked fashion and independently with a 2-month interval between each set. The reader was masked to the results of previous readings. The findings were compared with the surgical findings. The number of correctly identified and classified fistula and the sensitivity and specificity were determined. Twenty fistulas were present at surgery: 14 transsphincteric fistulas and six intersphincteric fistulas. Eighteen fistulas were correctly identified with the radial (R) and combined coronal sagittal (CS) sequences. In all other sequences or combinations of sequences all 20 fistulas were identified. Classification was correct with A in 16 patients, with R in 15, with CS in 15, with AR in 18, with ACS in 17 and with ARCS in 18. The sensitivity and specificity were optimal using AR or ARCS (0.86 and 1 respectively). The optimal and most time-efficient imaging protocol for endoanal MRI of perianal fistulas thus comprises the axial and radial imaging planes. Received 29 September 1997; Revision received 13 February 1998; Accepted 17 March 1998     

Requests for body computed tomography: increasing workload, increasing indications and increasing age

Increasing numbers of increasingly elderly patients were being examined in our Body CT department. At the same time, some of our clinical colleagues perceived that their patients might be discriminated against on the basis of their age when allocating CT time. We therefore studied the population trends in our department over a 10-year period. The ages of patients attending the Body CT department were collected from the hospital's computer information system from 1995 to 2000 and from handwritten logbooks for the months of September 1988 and 1998. Comparison was made with population trends within the hospital and local demographic data. There has been an average increase of 11% per annum in the number of examinations performed in the Body CT unit. The average age of patients examined increased from 52.7 years in 1988 to 58.9 years in 1998. The largest increase occurred in the over 75-year population (18% rise per annum). Hospital and local demographic population profiles changed little during the same period. We are performing increasing numbers of body CT examinations on increasingly elderly patients. This is probably due to an increased willingness to investigate and treat elderly patients, rather than changes in the local population. There is no evidence of a general discriminatory policy on the basis of age.     

Hemodynamic responses to increasing cycle cadence in 11-year old boys: role of the skeletal muscle pump.

Previous studies in adults have indicated a rise in the metabolic cost of increasing cycling cadence at constant work rates. This study examined the metabolic and cardiovascular responses to pedaling rates of 41, 63, and 83 rpm at both zero-load and 50-watts load in 12 prepubertal boys. Increasing cadence from 41 to 83 rpm produced a 52.9% and 23.1% rise in gross energy expenditure in the two work conditions, respectively, despite the constant external work rate. This augmented energy expenditure was accounted for entirely by internal work, as no changes in work metabolic cost (difference between loaded and unloaded cycling) were observed as cadence increased. The rise in energy expenditure with higher pedaling rate during the zero load and 50 watt conditions was accompanied by increases in both heart rate and stroke volume. Arterial venous oxygen difference did not change with increased cadence but was significantly higher with loaded cycling, suggesting that skeletal muscle pump effectiveness is negatively influenced by increased load but not by increased pedaling rate.     

Skiing injuries: the increasing workload.

All skiing injuries presenting to a fracture clinic during the period December 1992 to April 1993 were studied. Fifty five patients with 59 injuries were treated during this period. Thirty (54.5%) were male and 25 (45.5%) female. The mean age was 34 years (range 9-61). The anatomical distribution of injuries seen corresponded very closely with those seen in much larger studies abroad. There were 35 upper limb injuries (59.3%), 22 lower limb injuries (37.3%), with only two spine and trunk injuries (3.4%). While only two patients underwent surgery abroad, a further 12 needed surgical intervention on return, requiring a total stay of 61 'inpatient days'. The bulk of the workload was, however, on an outpatient basis, with a total of 172 appointments. Many advances have been made towards improving the safety of skiing. However with skiing becoming increasingly popular we can expect an increasing workload and cost associated with such injuries.     

Carotid-cavernous fistulas: embolization through the superior ophthalmic vein approach

Five patients aged 17-33 years with traumatic carotid-cavernous fistulas (CCFs) were treated by antegrade embolization through a superior ophthalmic vein approach, using cutdown technique on the upper eyelid. CCFs had recurred after prior treatment by multivessel ligation in three patients. Embolization through the ophthalmic vein resulted in long-term cure in three patients. The remaining patients were successfully treated by embolization through the arterial approach after failure of the ophthalmic vein technique. This is a new and rewarding technique to treat patients with CCFs, especially when there has been carotid ligation, provided the ophthalmic vein is thickened and arterialized.     

Imaging of hemodialysis fistulas: limitations of MR angiography

The clinical feasibility and utility of a three-dimensional (3D) MR angiography (MRA) were evaluated in 20 patients with hemodialysis fistulas. All patients had well functioning shunts and were imaged with a fast imaging in steady precision (FISP) flow rephased and flow dephased sequence. For comparison digital subtraction angiography and color-coded image directed Doppler sonography were used. Of 20 patients studied, 4 interrupted the MR examination due to pain in the shoulder of the extremity imaged. Of the 16 remaining fistulas only 2 were completely displayed on MR including feeding artery, anastomosis, and draining vein(s) on the MRA. Although 15 of 16 feeding arteries were shown by MRA, 10 of 16 draining veins and 14 of 16 anastomoses of the fistulas showed signal voids due to a lack of rephasing. Superimposing the MRA on the dephased images helped to demonstrate the shunt in another four patients having normal shunts. Thus, the utility of 3D MRA in imaging of hemodialysis fistulas is limited by technical problems and by patient's cooperation.     

Spinal arteriovenous fistulas of the filum terminale

The filum terminale is an anatomic structure at the end of the spinal cord. Only a few cases of AVFs of the filum terminale have been reported. These AVFs usually consist of a single communication between the anterior spinal artery and a single draining vein. We retrospectively analyzed the clinical and radiologic features and treatment of 4 patients with spinal AVFs of the filum terminale. Clinical manifestations and MR images are similar to those of spinal dural AVFs. All patients underwent surgical or endovascular treatment, resulting in complete occlusion. Clinical outcomes were good to excellent in all patients.