Archives of Disease in Childhood, 1978, 53, 120-125

Computed tomography in diagnosis of abdominalmasses in infancy and childhoodComparison with excretory urography

JOHN C. LEONIDAS, BARBARA L. CARTER, LUCIAN L. LEAPE, MAX L. RAMENOFSKY, ANDALAN M. SCHWARTZ

From the Department ofRadiology (Division ofPediatric Radiology), and Department ofSurgery (Division ofPediatric Surgery), New England Medical Center and Tufts University School ofMedicine, Boston,Massachusetts

SUMMARY Computed tomography (CT) of the abdomen and pelvis was performed in 26 instancesof suspected mass in 24 infants and children. The information obtained was compared to that ofstandard abdominal radiography and excretory urography (IVP). Results were analysed prospec-tively. CT was able to detect and define masses more precisely than abdominal radiography and IVP.The information obtained by CT, in a single noninvasive examination emitting minimal ionisingradiation, seems comparable to that offered by a combination of multiple radiological and otherimaging procedures. It is conceivable that with accumulating experience and further technologicalimprovement CT may become an excellent screening procedure in the investigation of abdominaland pelvic masses. The high cost of CT scanning may be offset by the benefits cited.

Computed tomography (CT) was developed byHounsfield of EMI-tronics Inc., Central ResearchLaboratories in 1972 and within a short timepractically revolutionised imaging of the skull andits contents (Hounsfield, 1973; Ambrose, 1973;Baker et al., 1974; New et al., 1974; Baker, 1975).CT scanning is a noninvasive and easily reproduciblediagnostic procedure carrying virtually no risk to thepatient, other than minimal radiation exposureequivalent to conventional radiological examinations(American Academy of Pediatrics, 1977; Brasch etal., 1977). It is not surprising therefore that CTscanning has had a profound impact on the practiceof neurology, neurosurgery, and neuroradiology,having reduced sharply the need for more con-ventional diagnostic procedures, such as A-modeechoencephalography, intracranial pneumography,and radionuclide brain scanning (Baker, 1975).

Several reports indicate the usefulness of body CTscanning in adults (Alfidi et al., 1975; Sheedy et al.,1976; Carter et al., 1977), and in infants and childrenexperience with CT of the head, neck, and spine israpidly growing (Harwood-Nash and Breckbill,1976; Hammerschlag et at., 1976). Experience withbody CT in paediatric patients, however, is scant(Boldt and Reilly, 1977; Pinto and Becker, 1977), andReceived 21 June 1977

no attempt has been made to evaluate its performancein comparison with other radiographic techniques.Excretory urography (intravenous pyelography, IVP)has proved reliable in the diagnosis ofabdominal andpelvic masses in infants and children and is usuallythe first radiological examination to be performed. Acomparison was therefore made between CT scan-ning of the abdomen and pelvis and IVP, in a groupof infants and children known or suspected of havingabdominal and/or pelvic masses.

Materials and methods

Since July 1975, when a body scanner was installedat the Tufts-New England Medical Center, a total of26 CT scans of the abdomen and pelvis were per-formed in 24 infants and children. In all patients thepurpose of the examination was clinical suspicion ofamass. There were 16 males and 8 female patients,ranging in age from 1 day to 14 years. They had hadthe usual laboratory investigations and in additionplain film radiography and IVP before CT scanning.Other imaging examinations were only performed asindicated in the individual patient. Moreover CTstudies were limited to only those patients who stillpresented important diagnostic problems after otherimaging examinations had been completed.

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Computed tomography in diagnosis of abdominal masses in inlancy and childhood 121

All CT scans were performed with an OhioNuclear Delta scanner which produces two simul-taneous 13mm sections in 2-5 minutes. The unitprovides images in a 256 x 256 matrix. X-ray absorp-tion values are recorded from low absorption valuesof -1000 (air) to high absorption of +1000 (densebone). The absorption of water is 0. Detaileddescription of the principles and technique of CTscanning is given elsewhere (New et al., 1974;Harwood-Nash and Breckbill, 1976).

General anaesthesia was not used since sedationwith chloral hydrate (50 mg/kg to a maximum of100 mg/kg) proved adequate. In one newborn and allchildren older than 6 years no sedation was used.Each procedure was monitored by a radiologist whodetermined the necessity for additional views or

sections or injection of contrast medium.IVPs were obtained before CT scans. After an

initial abdominal radiography, sodium diatrizoate50% was injected intravenously (2-4 ml/kg of bodyweight) and films were taken at 3 and 5 minutes.Subsequent films were obtained as required forcomplete demonstration of the urinary tract. Thediagnostic contribution of CT was determinedbefore surgical confirmation or final diagnosis andcompared with that of the IVP. Data were collectedprospectively.

Certain limitations leading to biased conclusionsshould be noted. (1) Many abdominal masses provedto be outside the retroperitoneal space and lesslikely to have produced abnormalities on theIVP. Since the IVP is the initial evaluation of a

child suspected of having an abdominal mass, weconsidered the comparison valid. (2) The results ofthe IVP were available during the interpretation ofCT. (3) Experience with CT was limited, especiallyduring the early period of the study. With additionalexperience the accuracy of interpretation of CT scans

increased. (4) Motion artefacts on CT scans causeddegradation of the image in some instances. Greaterapplication of CT to paediatrics is expected with thelatest generations ofCT scanners now available, withscan times of 2-5 seconds. Although motion artefactsmay still be present, they will be sharply reduced.(5) Intravenous and oral contrast material for scan-

ning was used sparingly in our patients, a fact whichhas undoubtedly limited information.To facilitate comparison of data between IVP and

CT scanning an arbitrary scoring system wasdevised. A normal study was given a score of 0. Ifboth studies were positive and provided similarinformation, each was given a score of 1. If eitherstudy was the only one positive, or it offered addi-tional information not obtained from the other, itwas given a score of 2. False-positive results were

given a negative value (-I or -2 depending on

whether the other examination was also misleading).False-negatives were assigned 0. The presenceof a mass and its anatomical position and sizewas confirmed in the majority of cases by surgicalexploration, and its nature by histological examina-tion. In some instances exploration was carried outonly to confirm absence of disease. In a few casesstrong clinical evidence (i.e. known primary neo-plastic disease) supported by positive findings on anumber of imaging procedures indicated thepresence and extent of tumour. Absence of diseasewas most often established by lack of any abnormali-ties on a variety of diagnostic tests and imagingexaminations, disappearance of symptoms and signs,and no evidence of abnormality on follow up.

Results

Table 1 summarises the abdominal and pelvic massesfound. Comparison of the diagnostic performance ofIVP and CT is given in Table 2. 2 patients had IVPsand CT scans twice.

Table 1 Final diagnosis in 24 patients

Neural crest tumour 6Rhabdomyosarcoma 3Retroperitoneal lymphangioma 2Wilms's tumour 2Ovarian dermoid 1Ureteropelvic junction obstruction 1Choledochal cyst 1Hydrops of the gallbladder 1Retroperitoneal haematoma 1Normal 6

Total 24

CT scanning and IVP showed similar informationin 12 instances. In 3 cases of neural crest tumour CTgave superior information (better definition of intra-spinal extension of tumour in 1, calcification enhanc-ing the diagnostic probability of neuroblastoma in asecond (Fig. 1), and correct localisation of tumour inthe presacral space in a third). In one case ofrhabdomyosarcoma soft tissue tumours were shownby CT but not by IVP. One Wilms's tumourarising from the anterior surface of the kidney gavethe impression of an extrarenal mass on IVP, but itwas correctly defined as an intrarenal tumour by CT.Ultrasound, however, also gave correct informationin this case. Diseases of the liver and gallbladderwere better defined by CT (Cases 13, 17, 18, Figs.2, 3), as expected by their nature. The only possiblefalse-positive information obtained by CT was inCase 24, a 13-year-old girl who complained of per-sistent abdominal pain after trauma. A very smallmass was detected by CT anterior to the liver, un-confirmed by any other test, but she soon became

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122 Leonidas, Carter, Leape, Ramenofsky, and Schwartz

Table 2 Comparison offindings between IVP and CT

Case Abdominal x-rayno. Sex Age Clinical findings and IVP CT Final diagnosis Comments

1 F 4} yr Abdominal mass

M

M

M

M

F

F

M

F

M

M

M

M

7m ,,

I yr Urinary retention;constipation

2 yr Abdominal mass

10d go

4m ,,

6 m Persistently raised VMApostoperatively

2 yr Abdominal mass

7 yr Abdominal pain andneurological deficit

14 yr Mass in groin

3 m5 m3 yr7 m

0*

0*

2

2

0*

2

Abdominal mass9..

..9

.. 2

2 yr Epigastric mass

14 F 2i yr Abdominal mass15 M I d ,,

16 M 11 yr Haemophilia; flank pain17 M 4 yr Abdominal pain; vomiting

18 M 13 yr Aplastic anaemia,abdominal pain, fever

19 F 12 yr Persistent abdominal pain

20 F 4 m Twin of patient withneuroblastoma

21 M 7 yr Abdominal pain; anaemia;neoplastic cells in bonemarrow

22 M 2 yr Persistent diarrhoea; raisedVMA on one occasion

23 M S w Questionable abdominalmass

24 F 13 yr Abdominal pain aftertrauma

2

0*

0*

-1

0

0

2 Retroperitonealganglioneuroblastomawith intraspinal component

Retroperitonealneuroblastoma

Presacral neuroblastoma

Retroperitonealneuroblastoma

Retroperitonealneuroblastoma

Adrenal neuroblastoma(cystic)

Neuroblastoma in para-aorticnode; liver metastases

Rhabdomyosarcoma ofbladder and peritoneum

Recurrent pelvicrhabdomyosarcoma

Extensive pelvic andabdominalrhabdomyosarcoma

Retroperitoneal lymphangiomaRetroperitoneal lymphangiomaWilms's tumourWilms's tumour

2 Radiation atrophy of R lobeof liver with compensatoryhypertrophy of L lobe

1 Ovarian dermoidI Hydronephrosis caused by

ureteropelvic junctionobstruction

I Retroperitoneal haematoma1 Choledochal cyst

I Hydrops of gallbladder

0 No evidence of disease

0

0

-1

0

0

0

0

No evidence of disease

Leukaemia

No evidence of disease

No evidence of disease

Indeterminate; now well

Extent of tumour moreaccurately defined by CT;extradural extension bestdefined by myelography

IVP suggested intravesicaltumour

Calcification detected by CTonly

Cystic mass identified by IVPand CT; neuroblastomadetected microscopically onwall of adrenal cyst

Liver metastases 1-3 mm indiameter

Ureteric obstruction bytumour with hydronephrosison IVP and CT; multipleintra-abdominal metastaticfoci best defined by CT

Intrarenal origin of tumourbest defined by CT

Identification of nature of massby CT averted operation

Cyst shown equally well byultrasound

Oral cholecystographyinformative

IVP false positive, suggestingpelvic mass; CT indicatedureteral displacement bypsoas muscle

IVP questionably positive foradrenal mass

Negative exploratorylaparotomy

Small mass anterior to livershown on CT may haverepresented haematoma

O = negative test; 0* - false negative; -1 - false positive. For explanation of other numbers, see text. VMA = vanillylmandelic acid.

asymptomatic. The finding on CT may have repre- were two false-positive examinations by IVP (Casessented a small haematoma. 19, 22). In both, correct information from CTIVP was superior to CT only in a case of right scanning avoided abdominal exploration for these

congenital hydronephrosis, better defining the normal children. In addition, the nature of the massureteropelvic junction obstruction as a cause. There in Case 13 proved on CT not to be a metastasis

2

3

4

5

6

7

8

9

10111213

1

I

I

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Computed tomography in diagnosis ofabdominal masses in infancy and childhood 123

Fig. 1 Case 4. (a) CT scan____r .with contrast enhancement at

the level of the kidneys showslateral displacement ofboth the

(a1) right (RK)and left kidney (LK)by a large mass anterior to thespine. Arrows indicate calcifi-cations within the mass; v =vertebra. (b) IVP shows themass but there are no detectablecalcifications. Lymph nodeenlargement was therefore con-

. .sidered in the differentialdiagnosis. At operation a largeneuroblastoma was found.

(I;)

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124 Leonidas, Carter, Leape, Ramenofsky, and Schwartz

Fig. 2 Case 13. Postoperative CT scan 17 months after right nephrectomy for Wilms's tumour. Palpable epigastricmass, seen also on IVP. CT scan shows atrophy of the right lobe of the liver (RL) secondary to radiation injury, andcompensatory hypertrophy ofthe left lobe (LL). v = vertebra, LK = left kidney (contrast is seen within its collectingsystem), ri = rib; S = spleen; gb = gallbladder. Black areas represent air within the bowel.

Fig. 3 Case 17. Choledochal cyst (CC) and dilated intrahepatic bile ducts (ihd). There was no palpable mass onexamination and there was no evidence ofjaundice at this time. RLL = right hepatic lobe; LLL = left hepatic lobe,S = spleen; v = vertebra.

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Computed tomography in diagnosis of abdominal masses in infancy and childhood 125

obviating the need for laparoscopy. The overallperformance of CT scanning was superior, with ascore of 26 versus 15 for the IVP.

Discussion

The data obtained from this small group of infantsand children suggest that CT scanning of theabdomen and pelvis is capable of accurately localis-ing masses and in many instances of providinganatomical information not available by conven-tional abdominal radiography and IVP. It is perhapsunfair to compare CT and IVP on a one-to-one basis,since most of the information expected from thelatter is limited to the urinary tract and retro-peritoneal space. This limitation in itself, however,emphasises the value of CT which is capable ofstudying all intra-abdominal structures and tissues inone examination. Many times the localisation of amass (whether intraperitoneal or retroperitoneal) isnot clinically obvious, and investigation starts withan IVP, pursued if necessary with upper gastro-intestinal contrast study, barium enema, gallbladderseries, abdominal echography, and some times evenarteriography. When the information of all suchimaging methods is combined it probably matchesthat obtained from CT scanning, but at the expenseof time, higher radiation exposure, and often the riskof morbidity related to invasive procedures such asarteriography. At the present time CT scanning isexpensive ($195 without and $245 with contrastenhancement at this institution, compared to $122for an IVP). This disadvantage is offset by signifi-cantly improving the quality of patient care as moreinvasive examinations are avoided and the danger ofunnecessary operations is minimised. It is possiblethat overall cost may actually decrease with the useof CT because of the need for fewer diagnostic tests,shorter hospitalisation, and restriction of surgery,though a definite statement will have to await furtherstudies. It is hoped that with increasing experienceand improvement in technology CT scanning willbecome the first procedure to be performed inchildren suspected of having an abdominal or pelvicmass, and it may be the only one needed in somecases.

Specific advantages of CT scanning suggested byour study are: (I) CT may offer information regard-ing both the intraperitoneal and extraperitonealtissues. It is especially helpful in the investigations ofthe liver and biliary tract without contrast media.(2) It can show small differences in x-ray absorptionand identify masses in or adjacent to other structuresof 'water density' not defined by conventional radio-graphy. It differentiates cystic from solid structures.Its ability to show minute calcifications within cer-

tain masses not seen by conventional radiographictechniques has been valuable in this study. (3) Thesize of a lesion is a limiting factor for CT. Smallmetastatic foci in the liver and a small (1 cm indiameter) para-aortic node infiltrated with neuro-blastoma were missed. (4) It is likely that the IVPwill remain superior to CT in better defining intrinsicabnormalities of the collecting system of the urinarytract.

References

Alfidi, R. J., Haaga, J., Meaney, T. F., Maclntyre, W. J.Gonzalez, L., Tarar, R., Zelch, M. G., Boller, M., Cook,S. A., and Jelden, G. (1975). Computed tomography of thethorax and abdomen. Radiology, 117, 257-264.

Ambrose, J. (1973). Computerized transverse axial scanning(tomography). II. Clinical application. British Journal ofRadiology, 46, 1023-1047.

American Academy of Pediatrics, Committee on Radiology(1977). Computerized tomography: a perspective in thepediatric patient. Pediatrics, 52, 305-308.

Baker, H. L. (1975). The impact of computed tomography onneuroradiologic practice. Radiology, 116, 637-640.

Baker, H. L., Jr., Campbell, J. K., Houser, D. W., Reese,D. F., Sheedy, P. F., and Holman, C. B. (1974). Computerassisted tomography of the head: an early evaluation.Mayo Clinic Proceedings, 49, 17-27.

Boldt, D. W., and Reilly, B. J. (1977). Computed tomog-raphy of abdominal mass lesions in children. Initialexperience. Radiology, 124, 371-378.

Brasch, R. C., Gooding, C. A., Boyd, D. P., and Korobkin,M. (1977). Radiation dosimetry of computed tomographic(CT) body scanners in pediatric patients and phantoms.Presented at the 14th annual meeting of the EuropeanSociety for Paediatric Radiology, Lucerne, Switzerland,May 12-14.

Carter, B. L., Morehead, J., Wolpert, S. M., Hammerschlag,S. B., Griffiths, H. J., and Kahn, P. C. (1977). CrossSectional Anatomy, Tomography and Ultrasound Cor-relation. Appleton-Century Crofts, New York.

Hammerschlag, S. B., Wolpert, S. M., and Carter, B. L.(1976). Computed tomography of the spinal canal.Radiology, 121, 361-367.

Harwood-Nash, D. C., and Breckbill, D. L. (1976). Computedtomography in children. A new diagnostic technique.Journal of Pediatrics, 89, 343-357.

Hounsfield, G. N. (1973). Computerized transverse axialscanning (tomography) 1. Description of system. BritishJournal of Radiology, 46, 1016-1022.

New, P. F., Scott, R., Schnur, J. A., Davis, K. R., andTaveras, J. M. (1974). Computerized axial tomographywith the EMI scanner. Radiology, 110, 109-123.

Pinto, R. S., and Becker, M. H. (1977). Computed tomo-graphy in pediatric diagnosis. American Journal of Diseasesof Children, 131, 583-592.

Sheedy, P. F., Stephens, D. H., Hattery, R. R., Muhm, J. R.,and Hartman, G. W. (1976). Computed tomography of thebody: initial clinical trial with the EMI prototype. AmericanJournal of Roentgenology, 127, 23-51.

Correspondence to Dr John C. Leonidas, Depart-ment of Radiology, Boston Floating Hospital, 171Harrison Avenue, Boston, Massachusetts 021 1 1,USA.

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