Somatom Sessions 08

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Clinical 3D Imaging Has Its Time Finally Arrived?

Case Reportson Volume Imaging

SOMATOMS E S S I O N S

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This is the eighth issue of Siemens SOMATOMSessions.

It provides insights from clinical 3D imaging together with

case reports from Siemens SOMATOM Volume Zoom users.

This issue focuses on the many improvements made

possible through volume imaging.

As always we would appreciate your suggestions and

comments.

Xiaoyan Chen, M.D.

Editor of SOMATOM Sessions

CONTENTS

FROM THE EDITOR

Letter from the Editor Page 2

Clinical 3D Imaging

Has Its Time Finally Arrived? Page 3

An arteriovenous malformation involving

the second and third digits of the left foot Page 10

MSCT diagnosis on conductive hearing loss Page 12

Pancreatic Carcinoma Page 14

Chronic Intestinal Ischemia:

Superior and Inferior Mesenteric Artery

Stenosis Depicted by Multislice CT Page 16

Axillary Deep Venous Thrombosis after

PORT-A-CATH Insertion Page 19

Multislice Spiral CT: Phlebography of the upper

extremity in a patient with shunt thrombosis Page 21

The drugs and doses mentioned herein are consistent with the approval

labeling for uses and/or indications of the drug. The treating physician bears

the sole responsibility for the diagnosis and treatment of patients, including

but not limited to the parameters selected during image acquisition and

postprocessing and any drugs and doses prescribed in connection with

such use.


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Three-dimensional imaging (3D) for CT applications was

introduced shortly after clinical CT scanning became a reality

in the late1970s. Whether through work done by Gabor

Herman and associates at the University of Pennsylvania or

Mike Vannier and associates at the Mallinckrodt Institute

of Radiology, 3D imaging was viewed as a way of extract-

ing more information from a series of transaxial CT scan

slices. Not surprisingly early applications involved bone espe-

cially in areas like the skull and craniofacial regions (regions

of high CT contrast and anatomic zones less affected by

patient motion or breathing). Although most radiologists

at the time were not enthusiastic about 3D reconstructions,

our referring physicians found them extremely helpful in

patient management decisions in complex cases. Over the

next15 or so years, 3D imaging continued to evolve with

the introduction of faster computer processing times, lower

priced workstations with better price/performance profiles,

and new rendering algorithms (i.e., volume rendering).

Yet, despite these and many other advances, 3D imagingcontinued to be a study performed in a select group of

institutions for a limited set of applications.

It is debatable why the progress of 3D imaging in the

radiologic environment was so slow but a number of reasons

have been suggested including:

High cost of workstations. Perceived notion that 3D had limited clinical applications.

3D was felt to be of value only to the referring physicianbut not to the radiologist.

Difficulty in using 3D workstations due to poor systemdesign and limited functionality.

A killer app (application) had not been developed todrive 3D imaging into the mainstream.

Major equipment vendors like Siemens Medical Systemsand GE did not push 3D as a mainstream product.

Poor reimbursement for 3D studies (especially thephysician component).

What really began to change the equation was the devel-

opment of spiral CT and the ability to obtain true volume

data sets which were ideal for 3D or volume imaging. With

the continued development of spiral CT scanning from a

technology where one could acquire 12 seconds of data to

a technology that could acquire up to 100 seconds of data,

things really began to change. New applications for CT

began to develop based on these new technologies and

capabilities. The role of 3D imaging was becoming more

of a core function of CT and inseparable especially with

applications like CT angiography and virtual endoscopy. The

introduction of multidetector CT and its advances for vas-

cular imaging continued this development cycle which has

been driving 3D imaging to become more of a standard

exam rather than a unique procedure. In fact, every scanner

manufacturer now recommends or ships a workstation

capable of 3D imaging with their high-end scanners (multi-

detector CT scanners (MDCT). Yet, there is still the feeling

among some radiologists that 3D imaging is not yet suitable

for their practice.This seeming contradiction may seem

hard to explain but is based in great part on the resistance

of radiology and radiologists to change.

In our experience, the biggest limitations to the use of

3D imaging (and otherpostprocessing tools) in the clinical

environment include:

A lack of understanding of the advantages provided bythese techniques both from a clinical and patient care

perspective.

A lack of understanding of how to use these newtechniques including a lack of understanding on how to

use the workstation.

A lack of understanding of how to merge new technolo-gies into a busy clinical practice that already may be

overwhelmed by the volume of work and/or a staffing

shortage (both radiologists and technologists).

Resistance to change especially changes in workdistribution and flow.



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These limitations can be translated into a need for:

Education Training Clarification of workflow issues Staffing

None of these problems however is insurmountable.

I believe that education can come from any of several

sources including:

CME courses including courses with hands-on sessions.For example, the RSNA as part of its annual meeting

has hands-on sessions on the use of computers including

medical workstations. Siemens Medical Systems has

sponsored a hands-on course using the 3DVirtuoso work-

station the past two years in Orlando and will have a third

meeting May 18-20, 2001, also in Orlando, Florida.

Reading the radiologic literature (and pertinent literaturefrom other subspecialties) and noting the clinical role of 3D

imaging especially as it applies to CT angiography.

Getting information from the vendor of your workstationincluding detailed hands-on training on the use of the work-

station and better system documentation. The Somatom

Sessions is an example of vendor supplied information that

is valuable for your daily clinical practice.

Web-based educational sites like www.CTISUS.comwhere all of the 3D protocols are available including a large

teaching file of illustrated 3D cases.

Training reflects more on the ability to obtain technical

expertise on a 3D imaging system. Although every work-

station vendor provides some form of hands-on training

it usually is but two-days duration and this may be unsatis-

factory for either the radiology technologist or radiologist.

It is not suprising that the most common complaint about

a workstation and its use is lack of sufficient training. This

problem can be solved by either the 3D vendors providing

enhanced training (including through web-based training)

on or off-site or for the interested parties to go to sites with

similar equipment and learn in a more hands-on method.

Unless there is improvement in the training available the

use of 3D imaging will continue to lag other technologies.

Progress has been made as for example Siemens Medical

Systems has begun to focus 3D training in a centralized

location in Cary, North Carolina, USA.

Workflow issues and staffing are both separate but closely

intertwined problems. The decision as to who does the

3D imaging (radiologist vs. technologist) and where the

workstation is located are decisions that are made by indi-

vidual institutions. Although my experience is one where

the radiologists do the actual 3D imaging (including creat-

ing the images and filming them), other sites have found

a dedicated technologist (with radiologist supervision) to

be an ideal strategy. The advantages of the radiologist only

works in cases where the radiologist(s) is dedicated to

committing the necessary time and effort to the enterprise.

This is becoming more of an issue where most institutions

are understaffed and trying to cope with the clinical load

without adding new studies. However, this is shortsighted

as using a technique like CT angiography will decrease the

staffing (both radiologist and technologist) needed for more

invasive procedures like classic angiography. In addition,

our view that the future of imaging revolves around direct

3D viewing replacing axial CT scanned based imaging,

which will require primary radiologist participation. One

factor that will increase the radiologists willingness to be

the primary person for the 3D-image analysis is the avail-

ability of true real-time volume rendering. The Siemens

3DVirtuoso with the VolumePro upgrade will make this

wish a reality.The real-time rendering of this system allows

the radiologist to analyze even the most complicated cases

in a matter of minutes.



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Other sites have found that a dedicated technologist can

perform most of the routine studies and the radiologist

works in a more supervisory role as well as doing the more

difficult/complex cases. Advantages of this workflow relate

to less of a commitment of the radiologists time and may

provide more continuity especially in those groups where

a radiologist is not based at any one hospital or office. In

this model selection of the technologist is critical as they

should be an individual who is willing to learn what the pur-

pose of each study is and is committed to continuing edu-

cation. The person must be self-motivated and committed

to the project. The technologist will also need people-skills

to deal with both the radiologist and the referring physician.

This workflow issue is critical to the success of any 3D

program and will need to be decided on a case to case basis.

Although it would be ideal to have multiple workstations

connected over a high-speed network capable of doing 3D

imaging this is rarely the case today.The decision as to

where to physically place the workstation is therefore

critical. I have found that it is ideal to have the workstation

away from the scanner suite in a separate room or office.

This allows consultation with referring physicians without

interrupting the primary function of the CT scanner which

is to scan patients.

This separate 3D suite or lab allows for the centralization

of function especially when a number of different scanners

and/or modalities are networked to a single workstation.

For example, at Hopkins our 3D lab is connected by a

100 megabyte backbone to scanners in the hospital, the

adjacent outpatient center, the adjacent oncology center,

the emergency room and a remote site 10 miles away.

All images seamlessly reach the workstation for postpro-

cessing. However, with our 3D volumes increasing to over

10 cases per day as well as the need for rapid image turn-

around (minutes rather than days), the location of the

workstation will soon have to be closer to the scanners and

reading room.

Workflow issues are obviously a critical factor in the

success of a 3D operation. The timely performance of a

CT scan will be negated if there is a time lag until the 3D

images are generated. Although many 3D studies do not

require an immediate turnaround, other applications are

very time-sensitive.These applications include acetabular

fracture repair (in select cases), suspected mesenteric

ischemia, and suspected aortic dissection.Training of enough

staff members to cover these off-hours cases is needed

to provide the 24/7 coverage demanded today. The use of

3D imaging in the acute setting is rapidly increasing.

Another problem with placing a workstation in a single

central location as 3D visualization becomes a primary

interpretation tool is that it would need to be located in the

scanner suite or in the area where films are interpreted.

This would potentially require a number of workstations

which would be cost-effective if used to enhance the

primary interpretation. Implementation of this paradigm is

beginning especially with the new design of the 3DVirtuoso

and its increased capabilities as a primary display and

analysis center.

Multidetector CT is probably the final brick that will push

3D imaging into the mainstream. Although I will not dis-

cuss the specific clinical advantages of MDCT, it is easy to

conclude that any 3D application that could be done pre-

viously can be done better due to a combination of factors

including narrower collimation, higher resolution imaging

and faster scan times.

MDCT also has resulted in many new applications for

CT now becoming a clinical reality. These include topics like

mesenteric angiography for ischemia, coronary artery

angiography and peripheral CT angiography. However, even

more than that is the practical reality of MDCT. While in

the prespiral era, a scan sequence of 35-50 images were

the rule, with multidetector spiral CT a typical study may be

anywhere from 150-600 slices.


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Even if film cost and storage were not an issue, the radio-

logist may become fatigued from looking at so many

images. 3D imaging or volume imaging may prove to be an

alternative. Viewing the entire data set as a volume with

an interactive 3D real time display may be ideal. The ability

to interactively segment out organs or organ systems will

help with more accurate detection of disease as well as

quantification of disease volumes. The use of an interactive

mode will also speed up the viewing process forboth the

radiologist and the referring physician. Another practical

factor is that studies like CT angiography cannot be truly

evaluated as axial images.The CT display must be more

like a classic angiogram and display the vessels in the for-

mat that show the vessels in a true vascular map. Volume

rendering is ideal for this task and provides breath-taking

images using the 3DVirtuoso.

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Fig. 1: Pancreatic cancer with vessel displacement:

3D CT angiograms demonstrate displacement of both

the gastroduodenal artery and the celiac axis.

ba

Although a detailed analysis of specific 3D applications is

beyond the scope of the article, a brief listing of the direction

we are going will give you the feel of how 3D imaging will

become not only mainstream but a central part of imaging

in the 21st century. Although classic 3D imaging tended

to focus on orthopedic imaging like acetabular fractures or

tibial plateau fractures the hottest areas of interest focus

on vascular imaging. The applications include:

Oncologic imaging 3D mapping of tumors for betterstaging of disease as well as for surgical planning. Specific

applications include staging pancreatic cancer (figure 1),

renal cell carcinoma (figure 2), primary liver tumors as well

as lung cancer.

This is shown both with volume rendering technique

(a) and MIP (b) techniques.



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Fig. 2: Renal cell carcinoma:

CT angiography is used to determine eligible candi-

ba

Fig. 3: Mesenteric ischemia: (a-b)

This CT angiogram demonstrates occlusion of the

SMA and IMA and collateralization through the celiac

ba

dates for a partial nephrectomy. The patients right

renal cell carcinoma was successfully resected.

axis and gastroduodenal artery through the artery of

Drummond.


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Fig. 4: Renal donor:

This dual phase CT angiogram provides definition of

both the potential donors renal artery(s) (a) as well as

the venous anatomy (b).

ba

This study is used as the guide for laparoscopic

nephrectomy. Note the two left renal arteries.

Vascular imaging in addition to the evaluation of aorticaneurysms and dissection we are now doing CT angio-

grams for mesenteric ischemia (figure 3) and to look at

bowel activity in Crohns disease. Evaluation of carotid or

renal artery stenosis are two other strong applications.

CT is at least 40% cheaper than a conventional angiogram.

Organ donor imaging 3D CT angiography is the goldstandard for the preoperative evaluation of potential renal

donors (figure 4). It is also our study of choice for evaluat-

ing patients who are potential living related organ donors

or transplant recipients.

ConclusionThe modification of an established workflow pattern is

difficult and at times will seem impossible. This is especially

true if the old system worked well and its members are

satisfied with its performance. To paraphrase an old saying

everyone wants progress but no one wants change. It

is only when the system becomes unworkable orunsatis-

factory that the window for change opens.The introductionof MDCT and the new real-time capabilities and functio-

nality of the 3DVirtuoso will provide the impetus by creating

an environment where a new paradigm will be needed.

We look forward to these changes and the potential inno-

vative solutions that will be its result.



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Table 1The factors, which are driving 3D imaging into the realm

of a commonly used and accepted clinical study (by the

radiologic community) include:

A better understanding of the clinical value addedby 3D imaging.

The growth of CT angiography and the demand forclinical studies by the referring physicians.

Better reimbursements for 3D. Wealth of supporting data in the radiologic literature. Easier to use 3D workstations.

Table 23D CT Imaging: WorkFlow Issues.

Where Should the 3D Image Processing be Done?

A dedicated 3D lab. Anywhere there is space to put a workstation. In the CT reading area. In the referring physicians office, clinic and/or the O.R. Near the CT scanner.

Table 3The biggest limitations to the use of 3D imaging and other

post-processing tools are:

A lack of understanding of the advantages providedby these techniques.

A lack of understanding of how to use these newtechniques.

A lack of understanding of how to merge new techno-logies into a busy clinical practice that already may be

overwhelmed by the volume of work and/or a staffing

shortage (both radiologists and technologists).

References

www.CTISUS.com contains all the CT protocols for single

and multidetector CT as well as complete references for

all of the clinical applications. A lecture series on volumetric

3D imaging and Siemens MDCT is also available on the

site.

Elliot K. Fishman, M.D.

Professor of Radiology and Oncology

Johns Hopkins University School of Medicine

Baltimore, Maryland

U.S.A.


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An arteriovenous malformation involving theecond and third digits of the left foot

History55-year-old female patient with painful swelling of the

left lower foot. A CT angiogram was performed to assess

fora vascular malformation.

Technical Data

ResultsComputed tomography confirms the presence of an arterio-

venous malformation involving the second and third digits of

the left foot. Digital subtraction arteriography demonstrated

two major feeders from the dorsalis pedis artery as well

as multiple smaller feeders from the posterior tibial artery.

The CT angiogram demonstrates the complex arteriovenous

malformation with tremendous clarity when compared to

digital subtraction arteriography.The CTangiogram is limitedby the simultaneous visualization of the feeding arteries

and draining veins, however there is less staining of the nidus

of the AVM.Volume rendered views facilitate appreciation

of the three-dimensional relationships of this complex lesion

and were useful in planning embolotherapy.

CommentsMultislice spiral CT combined with 0.5 second gantry

rotation allowed imaging of the arterial supply of the left

leg from the knee through the toes with near isotropic

spatial resolution.As a result, small arteries and veins can

be visualized that were previously not identifiable by CT

scanning.

Maximum intensity projections provide a similar appearance

to that of the digital subtraction angiogram, while volume

rendering facilitates appreciation of three dimensional

relationships.

ScanRegion Foot

Scan length 480 mm

Slice collimation 4 x 1.0 mm

Table Feed/rotation 6 mm

Pitch 6

Scan direction craniocaudal

Rotation time 0.5 s

kV 140

mAs 120

Kernel uncertainScan time 40 s

Image Reconstruction

Reconstruction slice width 1.25 mm

Reconstruction increment 0.5 mm

Postprocessing

Maximum intensity projections and volume rendering

Geoffrey D. Rubin, M.D.

Associate Professor, Radiology

Stanford University School of Medicine,

Stanford, California, USA


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Fig. 1: AP and lateral maximum intensity projections

with an inverted gray scale demonstrate the entire

scan volume.The popliteal artery and the branches of

its trifurcation are demonstrated to enhance intensely

in the lateral aspect of the upper leg while early filling

of the saphenous venous system is observed medially.

Fig. 2: Detailed view comparing DSA and MIP-CTA

views of the forefoot. The AVM nidus is clearly seen on

the DSA examination involving the second and third

digits. Although the nidus is not opacified to the same

level on the CTA, its position is inferred by the manysmall vessels observed over the entire second digit in

the region of the metatarsal head as well as over the

medial aspect of the third digit.The DSA view is a com-

pilation of two views acquired five seconds apart show-

ing during the arterial and venous phases of the study.

The two views were added together to create a view

that is comparable to the CT, showing both arterial and

venous anatomy.

Fig. 3: Left and right lateral and AP volume renderings

of the forefoot demonstrate the three dimensional

relationships of this complex AVM. Vessels with grea-

test enhancement are encoded in white, followed

by intermediately enhancing vessels in red and less

enhancing vessels encoded in magenta.

3a 3b

3c


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Fig. 1: Axial image Fig. 2: MPR image

Fig. 3: VRT image Fig. 4: VRT image

Fig. 5: VRT image

Fig. 1-4: Ossicular interruption.

VRT images were generated from MPR images.

Fig. 5-6: Normal anatomical structure of the inner ear.

Fig. 6: VRT image


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Pancreatic Carcinoma

History65-year-old female patient with painless jaundice and

back pain for ten days. Ultrasound revealed stones in the

gallbladder, an extra- and beginning intrahepatic cholestasis

and an enlarged head of the pancreas with suspected

hypodense formation in the head of the pancreas. Lab works:

slightly incrased amylase and lipase, elevated phosphatase

and bilirubin and CA 19-9.

ERCP: Filiform stenosis of the common bile duct in the head

of the pancreas indicates carcinoma of pancreatic head.

Dilated pancreatic duct.

Technical Data

Patient preparationOral contrast medium:

1000 ml iodinated oral contrast material 1 h prior to

the examination, 500 ml water 10 minutes prior to the

examination.

Right side position for 5 minutes before scanning;

Spasmolysant immediately before scanning;

Supine position during scanning.

ResultsT1 carcinoma of the pancreatic head (histologically con-

firmed). Dilated common bile duct, slightly dilated pancreatic

duct. Small circular hyperdensity in the head of pancreas

surrounded by a small hypodense mass, which can not be

delineated from the portal vein and the superior mesenteric

vein on tansverse images. Coronal and sagittal MIP and

MPR confirm that the circular hyperdensity is the enhancing

wall of the bile duct, surrounded by a small hypodense

T1-tumor. Sagittal plane demonstrates the encasement of

the portal vein of less than one quarter of the circumference.

Therefore according to the criteria published by Lu et al.

1997 infiltration of the portal vein can be excluded. These

findings (T1 stage; no infiltration of the peripancreatic

vessels) were confirmed intraoperatively.

ReferencesLu DSK, Reber HA, Krasny RM, Kadell BM, Sayre J (1997)

Local staging of pancreatic cancer: criteria forunresectability

of major vessels as revealed by pancreatic-phase,

thin-section helical CT. AJR 1997; 168:1439-1443.

Scan

Region upper abdomen

Scan length 156 mm

Slice collimation 4 x 1 mmTable feed / rotation 4 mm

Pitch 4

Scan direction caudocranial

Rotation time 0.5 s

kV 120

mAs 165

Kernel B30

Scan time 23 s

Contrast Injection

Volume 120 ml (non-ionic contrast medium)

Concentration 370 mg iodine/ml

Flow rate 4 ml/s

Start delay 35 s

Image Reconstruction

Reconstructed slice width 1.25 mm/3 mm

Reconstruction increment 1 mm/3 mm

Postprocessing

Multiplanar reformations +


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Fig. 1: Axial image

This image shows a hypodense tumor in the head

of the pancreas, the enhancing common bile duct, the

slightly dilated pancreatic duct and the encasement of

the superior mesenteric vein for less than one quarter

of the circumference.

Fig. 2: Coronal MIP-reconstruction

This image shows normal calibre of the superior

mesenteric vein and the portal vein, the dilatation and

the enhancing wall of the common bile duct.

Pay attention to the small line of fatty tissue between

the portal vein and the carcinoma.

No suspicion of vascular infiltration on coronal MIPs.

Fig. 3: Sagittal MPR

This image shows the tumor in the pancreatic head

and the encasement of the portal vein for less than one

quarter of the circumference. Slight irregularity of the

lumen of the portal vein.

Ulrich Baum, MD

Institute of Diagnostic Radiology

University of Erlangen-Nuremberg

Maximiliansplatz 1

D-91054 Erlangen

Tel. ++49/9131/8 53-6066

Fax ++49/9131/853-6068

e-mail: [email protected]


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Chronic Intestinal Ischemia: Superior and InferiorMesenteric Artery Stenosis Depicted by Multislice CT

HistoryA 64-year-old woman has complained of chronic perium-

bilical pain for six months. The pain appeared half an hour

after each meal. She had a history of hypertension, heavy

smoking and right carotid bifurcation surgery. The pain was

also diffusing to her back. She lost 10 kg in 6 months. No

abnormality was detected by the sonography of the upper

abdomen, gastroscopy and coloscopy and the biology.

A multislice CT of the abdomen was performed to rule outvascular mesenteric lesions.

Technical DataThe spiral CT was acquired with a multislice spiral CT

(SOMATOM Volume Zoom, Siemens Medical Engineering,

Forchheim, Germany).

The following scan parameters were used:

Clinical comments and summaryThe angiographic criteria of a chronic mesenteric ischemia

consist in the presence of significant stenosis or obliteration

of 2 of the 3 main gastrointestinal arteries. For this patient,

the only large and safe artery of the intestine is the celiac

trunk. This case illustrates the ability of the Volume Zoom

to provide a precise vascular mapping and detect the arterial

lesions in the intestinal arteries. The 3D reconstructions

obtained with the Volume Wizard (MIP, MPR, SSD) superblydemonstrate the collateral vascular supply. Since the effi-

cacy of CT in the diagnosis of acute intestinal ischemia has

been demonstrated in comparison to angiography, further

studies will have to determine its performance and role in

the diagnosis of chronic intestinal ischemia for which angio-

graphy is still the imaging modality of choice.

References[1] Klein, H. M., Lensing, R., Klosterhalfen, B., Tons, C.,

Gunther, R.W.: Diagnostic imaging of mesenteric infarc-

tion. Radiology 1995 Oct; 197(1):79-82

[2] Yamada, K.,Saeki, M., Yamaguchi, T., Taira, M., Ohyama,Y.,

Ashida, H., Sakuyama, K., Ishikawa, T.: Acute mesenteric

ischemia. CT and plain radiographic analysis of 26 cases.

Eur Radiol 1999;9(7):1267-76

[3] Boley, S. J., Brandt, L. J., Veit, F. J.: Ischemic disorders

of the intestine. Curr Prob Surg, 1978, 15: 1-85.

[4] Rogers, A. L., Cohen,J.L.: Ischemic bowel disease.

Gastroenterology, 4ed.,vol.3, Editor: J. E. Berk. Philadelphia,

Saunders, 1915-1935.

KV 120mAs 90

Slice collimation 4 x 1 mm

Slice thickness 1.5 mm

FOV 37.9 cm

Recon increment 1 mm

Rotation time 0.5 s

Feed per rotation 8 mm

Total acquisition time 19.7 s

Reconstruction algorithm B20

Total number of images 313Injection protocol: brachial vein,

Nonionic contrast medium at

350 mg I/100 ml. Injection volume 100 ml

Injection rate 4 ml/s

Start delay 40 s


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Fig. 1: Maximum Intensity Projection (MIP, Fig. 1a)

and Volume Rendering Technique (VRT, Fig.1b) images

in a saggital oblique orientation demonstrating a

superior mesenteric artery stenosis.

Fig. 2: Left obliquely oriented coronal MIP (Fig. 2a)

and VRT (Fig. 2b) views showing collateral vascular

supply to the superior and inferior mesenteric arteries

originating from the celiac trunk and its branches.

1a 2a

2b1b


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Fig. 3: Obliquely oriented axial multiplanar reconstruc-

tion (MPR) at the level of the origin of the superior

mesenteric artery. A luminal interruption is observed

with an intramural blood clot (white arrow).

Fig. 4: Saggital oblique MPR showing a stenosis at the

origin of the inferior mesenteric artery (white arrow).

18

Chronic Intestinal Ischemia: Superior and InferiorMesenteric Artery Stenosis Depicted by Multislice CT

Denis Tack, M. D.

Department of Radiology C.H.U. de Charleroi

Boulevard Janson 92

B-6000 CHARLEROI/BELGIUM

Phone: (32 71) 25 1525

Fax: (32 71) 25 17 09

E-mail: [email protected]


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Axillary Deep Venous Thrombosis afterPORT-A-CATHInsertion

HistoryA 53-year-old woman complained of swelling of the left

arm for 24 hours. One week before, a Port-A-Cath

device had been inserted in her left jugular vein. She was

treated with chemotherapy for a gastric carcinoma.

Technical DataThe spiral CT was acquired with a multislice spiral CT

(SOMATOM Volume Zoom, Siemens Medical Engineering,

Forchheim, Germany).

The following scan parameters were used:

Clinical comments and summaryCentral venous access devices are often essential for the

administration of chemotherapy to patients with malignancy,

but its use has been associated with a number of compli-

cations, mainly thrombosis (1). Its sequelae include septic

thrombophlebitis, loss of central venous access and pulmo-

nary embolism. Phlebography is the imaging modality of

choice to demonstrate the venous thrombosis. However,

it is not appropriate to delineate precisely innominatal veincompressions that occur in the antero-posterior direction

as lymphadenopathies do in the anterior uppermediastinum

(Figure 1).This case shows the ability of multislice CT to

depict the venous thrombosis and its causes, the insertion

of a catheter in a compressed left innominatal vein.The

MIP images obtained with the Volume Wizard perfectly

demonstrate the collateral vascular supply to the chest

wall and obviate the need for venography. Essential to the

technique is the injection of an iodine contrast of low

concentration in both forearms.This allows opacification ofthe bilateral thoracic veins simultaneously. The dilution is

essential to avoid artifacts in the superior vena cava. Some

authors recommend a preventive treatment of venous

thrombosis related to Port-A-Cath device with a low mole-

cular weight heparin (2).

References[1] Lersch, C., Eckel, F., Sader, R., Paschalidis, M.,

Zeilhofer, F., Schulte-Frohlinde, E., Theiss,W.:

Initial experience with Healthport miniMax and other peri-

pheral arm ports in patients with advanced gastrointestinal

malignancy. Oncology 1999; 57(4):269-75

[2] Monreal, M., Alastrue, A., Rull, M., Mira, X., Muxart, J.

Rosell, R., Abad,A.: Upper extremity deep venous

thrombosis in cancer patients with venous access devices

prophylaxis with a low molecular weight heparin

(Fragmin). Thromb Haemost 1996;75(2):251-3.

Region of interest: from the diaphragm to the

hyoid bone

Acquisition direction caudo-cranial

KV 120

mAs 77

Slice collimation 4 x 1 mmSlice thickness 1.5 mm

FOV 36.7 cm

Recon increment 1 mm

Rotation time 0.5 s

Feed per rotation 8 mm

Total acquisition time 17 s

Reconstruction algorithm B20

Total number of images 229

Injection protocol: Nonionic contrast medium

at 350 mg I/100 ml

Dilution of the contrast 1/4

Injection volume

in the left arm 50 ml at a rate of 2 ml/s

Injection volume

in the right arm 150 ml at a rate of 4 ml/s

Start delay 20 s


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20

Fig. 3, 4: Maximum intensity projection with 10 cm

thickness (Fig.4) and VRT (Fig. 3) images demonstrating

the normal right thoracic veins, the position of the

PORT-A-CATH device and the venous collaterals from

the left axillary region to the intercostal and mid vertical

thoracic vein.

Fig. 1, 2: Coronal MPR (Fig. 1) and VRT (Fig. 2)

at the level of the left jugular vein and the catheter.

Mediastinal and cervical bilateral lymphadenopathies,

and left axillary vein thrombosis.

3

1 2

4


Denis Tack, M. D.

Department of Radiology C.H.U. de Charleroi

Boulevard Janson 92, B-6000 CHARLEROI/BELGIUM

Phone: (3271) 251525, Fax: (3271) 25 17 09

E-mail: [email protected]


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Multislice Spiral CT: Phlebography of thepper extremity in a patient with shunt thrombosis

HistoryA 38-year-old patient with end stage renal disease presented

with massive swelling of the right forearm and a history

of repeated shunt thrombosis. Physical examination on

admission revealed normal perfusion of the dialysis shunt

on the right upper arm.

Spiral CT was performed on suspicion of central thrombosis

and to exclude mediastinal mass.

Technical DataScanner: SOMATOM Volume Zoom, Siemens, Germany

DiagnosisAcute central thrombosis of the right subclavian vein is

evident, without apparent anatomical reason (mass or

muscular hypertrophy). On the left side thrombosis of the

subclavian and axillary vein due to ipsilateral shunt throm-

bosis is shown. Multiple varicoid bypasses drain the left

upper extremity. Extensive opacification in vessels with

reduced blood flow is seen on the left arm because of cen-

tral vein thrombosis, whereas lower opacification is seenin the shunt on the right side due to high, arterialized blood

flow. A filiform stenosis of the right brachiocephalic vein is

demonstrated proximal to the confluence of the superior

cava vein.

CommentsWith MSCT an isotropic volume data set can be acquired

in a single breathold. Out of this data set, views from arbitrary

chosen directions can be processed. Only little contrast

material (50 ml) was needed to achieve sufficient contrast

enhancement of both brachiocephalic veins due to the

short acquisition time. The administration of contrast mate-

rial is a central issue for the assessment of vessels.Amount

and concentration of contrast material, flow rate and start

delay are important parameters for homogenous opacifi-

cation without inflow- or high contrast artifacts. In this

patient, the delay between the start of contrast material

injection and the spiral scan was chosen empirically.To

have visual control of optimal opacification, semiautomatic

bolus triggering techniques can be used to optimize the

start delay. With such techniques a further reduction of con-

trast material volume is possible at the expense of a slight

increase of radiation dose. Dilution of the contrast material

is necessary to avoid high contrast artifacts. Both luminal

and extraluminal pathology (i.e. tumor mass, anatomical

variants) can be assessed and information of both venous

and arterial vessels is provided. Details of thrombus mor-

phology are availible and exact planning of an interventional

procedure is possible.

Slice collimation 4 x 1 mm

Table feet 8 mm/s

Rotation time 0.5 s

Reconstructed slice width 1.25 mm

Reconstruction increment 1 mm

Total scan time 22 s

Thin slice MIP +

Contrast material Optiray 300, Schering, Germany

Total volume 50 ml, diluted with 50 ml NaCl 0.9%

Injection rate 2.0 ml/s

Start delay 50 s

Injection was performed in the left antebrachial vein and

the shunt on the right arm simultaneously with a power

injector.


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Multislice Spiral CT: Phlebography of theupper extremity in a patient with shunt thrombosis

In addition to the axial images, 3D postprocessing can help

visualize pathology within one image and in orientations

used from DSA.Thin slice MIP is an easy and quick method

to display the vascular anatomy without time consuming

editing procedures. Cross sectional images help to differen-

tiate adherent from floating thrombus and measurements

of the diameter of the vessel help choosing the correct

dimension of angioplasty catheter and stent.

The patient was treated interventionally with dilatation and

stent implantation.

Michael Lell, M.D.

Institute of Diagnostic Radiology

University of Erlangen-Nuremberg

Erlangen, GermanyFig. 1a-d: Axial images show the central thrombosis

of the right subclavian vein.

Fig. 2: Axial MPR image shows the thrombosis of the left

subclavian vein.Fig. 3: Oblique axial MPR image shows the thrombosis

of both right and left subclavian veins.


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4 5

Fig: 4, 5: MIP images show different views of the filiform

stenosis of the right brachiocephalic vein proximal to the

confluence of the superior cava vein.

Fig: 6,7: MPR (Fig.6) and MIP (Fig. 7) images show the

thrombosis of the left subclavian and axillary vein due to

ipsilateral shunt.

6 7


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MPRESSUMPublished by

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Professor of Radiology and OncologyJohns Hopkins University School ofMedicine, Baltimore, Maryland, USA

An arteriovenous malformationinvolving the second and third digits ofthe left foot

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Associate Professor,RadiologyStanford University Schoolof Medicine, Stanford, California, USA

MSCT diagnosis on conductivehearing loss

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Head of Radiology ClinicThe Hospital of Hlsingland SderhamnSweden

Pancreatic Carcinoma

Ulrich Baum, M.D.

Institute of Diagnostic RadiologyUniversity of Erlangen-NurembergErlangen, Germany

Chronic Intestinal Ischemia: Superiorand InferiorMesenteric Artery StenosisDepicted by Multislice CT

Denis Tack, M.D.

Department of RadiologyC.H.U. de CharleroiCHARLEROI, BELGIUM


Denis Tack, M.D

Department of RadiologyC.H.U. de CharleroiCHARLEROI, BELGIUM

Multislice Spiral CT: Phlebographyof the upper extremity in a patient withshunt thrombosis

Michael Lell, M.D.

Institute of Diagnostic RadiologyUniversity of Erlangen-NurembergErlangen, Germany

Somatom Sessions 08

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