767

.4, Emil J. Baithazar, M.D.

John H.C Ranson, BM., B.Ch.David P. Naidich, M.D.

Alec J. Megibow, M.D.

I’ Robert Caccavale, M.D.Matthew M. Cooper, M.D.

Acute Pancreatitis: Prognostic Value

of CT1

In 83 patients with acute pancreatitis, theinitial computed tomographic (CT) ex-

A aminations were classified by degree ofdisease severity (grades A-E) and werecorrelated with the clinical follow-up,objective prognostic signs, and complica-

.� tions and death. The length of hospital-

ization correlated well with the severityof the initial CT findings. Abscesses oc-

.4 curred in 21.6% of the entire group, com-pared with 60.0% of grade E patients.Pleural effusions were also more commonin grade E patients. Grades A and B pa-

,� tients did not have abscesses, and nonedied, regardless of the number of prog-

F nostic signs. Abscesses were seen in 80.0%

I ‘� of patients with six to eight prognosticsigns, compared with 12.5% of those withzero to two. The use of prognostic signswith initial CT findings results in im-proved prognostic accuracy. Early CT ex-

� �4 amination of patients with acute pancrea-titis is a useful prognostic indicator of

� morbidity and mortality.

‘� Index terms: Pancreas, computed tomography,

77.1211 #{149}Pancreatitis, 77.291

Radiology 1985; 156:767-772

� From the Departments of Radiology (E.J.B., D.P.N.,

A.J.M.) and Surgery (J.H.C.R., R.C., M.M.C.), NewYork University Medical Center, Bellevue HospitalMedical Center, New York City. Received January 10,1985; accepted and revision requested March 18, 1985;

revision received April 3. 1985.c RSNA, 1985

T HE degree, duration, and type of treatment of acute pancreatitis

are based on the early evaluation of the initial attack’s severity.

Until recently, this evaluation relied mainly on the presence on

absence of varied clinical parameters such as tachycardia, fever,

dyspnea, oligunia, protracted ileus, and tense abdomen. Several

methods of a more objective evaluation have been reported (1-7)

that potentially improve prognostic ability and prediction of com-plications. Among them, the statistical analysis of early objective

measurements of multiple risk factors, described by Ranson (2, 3),

has received wide attention and has been considered a reliable

prognostic indicator of the diseases’s severity. These objective prog-

nostic signs (grave signs or risk factors) have significantly im-

proved the initial assessment based on clinical criteria alone and are

used as guidelines in the decision-making process of selecting

proper medical or surgical treatment in our institution.

Since morbidity and mortality depend in great measure on the

local pancreatic and penipancreatic complications (i.e., abscess,

pseudocyst, hemorrhage), computed tomographic (CT) examina-

tion could play an important role in the initial assessment of the

severity of acute pancneatitis. For this reason, in the past 4 years wehave embarked on a comprehensive study designed to assess the

prognostic value of the initial CT examination in patients with

acute pancreatitis. Our objectives are (a) to describe, classify, andanalyze the early CT findings in acute pancreatitis; and (b) to assess

their predictive value based on correlation of early CT findings

with clinical and objective prognostic signs.

MATERIALS AND METHODS

Our study is based on a detailed analysis of CT, clinical, and laboratory

findings of 83 patients with acute pancreatitis admitted to our institution in

the past 4 years. There were 63 men and 20 women, aged 17-79 years, with a

mean age of 45 years. The clinical diagnosis was based on typical symptoms

such as nausea, vomiting, abdominal pain, and elevation of serum amylase

levels above 200 Somogyi units. The etiology of pancreatitis was chronic

alcohol abuse in 51 patients, cholelithiasis in 11, gallstones and alcohol in

five, hyperlipidemia in two, and miscellaneous or unknown in 14. There

were no cases of traumatic pancreatitis included in this series.

We used the previously reported objective prognostic signs (2, 3, 6, 7),

listed in Table 1, to assess the severity of the attack and its possible compli-

cations. All patients were initially treated by nasogastric suction, intrave-

nous fluid, and supportive therapy. We drained infected fluid collections

(abscesses) in 18 patients (21.7%), some upon initial evaluation and others as

complications developed. The clinical course, complications, treatment,

and response to treatment were recorded for all individuals, until death or

discharge from the hospital.

CT examinations were performed on a GE 8800 scanner (Milwaukee)

using standard technical parameters. Diluted 2% barium sulfate (E-Z-CAT,

E-Z-EM, Westbury, N.Y.) was used as oral contrast material, and a rapid

intravenous drip infusion of 30% diatrizoate meglumine (Reno-M-DIP

[Squibb]) was started immediately before scanning unless contraindicated.

Bolus injections were not used in this study.

A total of 152 CT scans were obtained, either as a single examination or as

consecutive, follow-up examinations approximately every 2 weeks. The

1. CT scan of normal pancreas in patient with clinical pan-

creatitis (grade A).

2. Diffuse enlargement of the pancreas without peripan-

creatic inflammatory changes (grade B).

3. Enlarged pancreas associated with haziness and in-

creased density of peripancreatic fat (grade C). Note

presence of diffuse fatty infiltration of liver.

I

4

8.

I

.#,

A

RESULTS

Of the 83 patients surveyed, 63 me-

covered with medical treatment alone

and were discharged, while 18 pa-

tients (21.7%) became septic and me-

Figures 1, 2, and 3

768 #{149}Radiology September 1985

initial examinations were performed

within the first 3 hospital days in 40 pa-

tients and between day 4 and 10 in 43 pa-

tients. In general, severely ill patients me-

ceived priority for CT examination,

making this sample unrepresentative of

all patients with acute pancreatitis ad-

mitted to our institution.

CT scans were interpreted without prior

knowledge of clinical findings or objec-

tive prognostic signs. The following con-

ditions were specifically looked for and

recorded: presence of fatty liver, gallblad-

den pathology, peritoneal effusion, and

pleural effusions.

In addition, we classified the type of

pancreatic inflammation seen on CT scans

into five categories. This classification was

based on an overall assessment of size,

contour, and density of the gland and per-

ipancreatic abnormalities. Specific mea-

surements were not used in this assess-

ment. We used the following grades,

which are similar to those reported in the

literature (8): grade A, normal pancreas

(Fig. 1); grade B, focal or diffuse enlarge-

ment of the pancreas (Fig. 2) (including

contour irregularities, nonhomogeneous

attenuation of the gland, dilatation of the

pancreatic duct, and foci of small fluid col-

lections within the gland, as long as there

was no evidence of peripancreatic dis-

ease); grade C, intrinsic pancreatic abnor-

malities associated with haziness and

streaky densities representing inflamma-

tory changes in the peripancreatic fat (Fig.

3); grade D, single, ill-defined fluid collec-

tion (phlegmon) (Fig. 4); grade E, two or

multiple, poorly defined fluid collections

2.

(Fig. 5) or presence of gas in or adjacent to

the pancreas (Fig. 6).

quired surgical drainage of abscesses.

One patient underwent surgery to me-

move a persistent pseudocyst. Five

patients with abscesses died, and one

other patient died of hepatic and

renal failure without evidence of pan-

creatic abscess. The relationship of

the objective prognostic signs to the

clinical course is shown in Table 2.

4

“I

4,

4

A

Figure 4

Volume 156 Number 3 Radiology #{149}769

a. b.

CT scan of enlarged body and tail of the pancreas (a) with associated fluid collection in left anterior pararenal space (b) (arrows) (grade D).

r Figure 5

� a. b.CT scan showing large fluid collections in the lesser sac and anterior pararenal space in patient with grade E pancreatitis. Note compression

. with partial obstruction of the duodenum and slight thickening of gallbladder wall (arrows).

Secondary CT Findings

Secondary CT findings that may

correlate with the severity of acute

pancreatitis were recorded. We ob-

served fatty infiltration of the liver in

21 patients (25.3%) (Fig. 3) from all

five grades of pancreatitis. Gallstones

were seen on CT scans in 12 patients

(14.5%), but were missed in a number

of other patients who proved to have

cholelithiasis on sonognams or during

surgical exploration. We observed

gallbladdens with thickened walls in

five patients, none of whom had gall-

stone pancreatitis (Fig. 5). Six patients(7.2%) had free fluid in the pemitoneal

cavity, five with grade D or E pancrea-

titis. We detected pleural effusions in

27 patients (32.5%). Effusions were

present in 41% of the 12 patients with

grade D and 65% of the 23 patients

with grade E pancreatitis. Bilateral ef-

fusions were seen in 22% of patients

with grade E pancreatitis.

In our morphologic evaluation, we

noted a diffuse involvement of the

pancreas in 68 of 83 cases and a seg-

mental distribution in the remaining

15 cases (18.1%). In nine patients

.�.

44

4

a. CT scan showing increased density of the peripancreatic retroperitoneal fat associated with extraluminal air (arrow) in patient with

pemipancreatic abscess.b. Bilateral, ill-defined, retroperitoneal fluid collections with multiple gas bubbles in patient with abscess (grade E).

4

I-

I

.4

r

‘4

I

.I�

A

Figure 6

770 #{149}Radiology September 1985

(10.8%), the inflammatory process in-

volved exclusively or predominantly

the head of the pancreas (Fig. 7); in

five, the body and tail; and in one,

only the tail of the pancreas. Swelling

of only the head of the pancreas was

present in three of the 1 1 patients

with gallstone pancreatitis (27.3%)

but in only six cases of all other types

of pancreatitis (8.3%). Two patients

with histories of previous pancreatitis

had pancreatic ductal calcifications

demonstrated on CT scans.

The patients were divided accord-

ing to the five grades, and the mela-

tionships between different grades

and the clinical course and prognosticsigns were analyzed. There were 12

patients (14.5%) in grade A, 19 (22.9%)

in grade B, 17 (20.5%) in grade C, 12

(14.5%) in grade D, and 23 (27.7%) in

grade E.

CT and Clinical Course

The relationship between early CT

findings and clinical course is sum-manized in Table 3. The average num-

ben of fasting days (nothing by

mouth) and days in the hospital come-

lated roughly with the severity of the

initial CT findings. Exceptions to the

general trend, however, occurred,

with some patients in grade B requir-

ing 4 weeks of hospitalization and

some in grade D requiring less than 2

weeks of treatment. No patient with

grade A pancreatitis was seriously ill,

and all five patients who died becauseof local complications (abscesses) mi-tially had grade D or E pancmeatitis.

Retropemitoneal, extraluminal air

was seen in four patients (Fig. 5) who

all proved at surgery to have infected

abscesses. In three cases, gas bubbles

were detected on CT scans in patients

with only one to three prognostic

signs within the first 24 hours of hos-

pitalization.

Fluid collections were initially seen

in 35 patients in grades D and E (or

45.7% of these combined grades). Fol-

low-up CT scans showed that in 19

patients (54.3%), fluid collections me-

solved without further complications,

while in 16 patients (45.7%), they did

not and eventually became infected.

Fluid collections developed in only

three patients who did not have them

initially and were classified as grade

C pancreatitis. One of these patients

ended up with a pseudocyst and two

with abscesses. In 15 patients, the in-

fected fluid collections were drained

between the 5th and 50th day hospi-

talized after an average stay of 25

days.

CT and Prognostic Signs

The relationship between early CTfindings and prognostic signs is

shown in Table 4. The relationship

between the number of prognostic

Figure 7

Volume 156 Number 3 Radiology . 771

signs and grades of pancreatitis varies

.� widely in patients with zero to five

prognostic signs. All patients with

more than five prognostic signs were

in grade E; however, a few patients

�pa with four and five signs were in

grades A and B.

When the number of patients with

�r abscesses or those that died were ana-lyzed as a function of combined CT

findings and prognostic signs (Table

5), the complication rate and progno-

sis could be better assessed. The num-

., ben of patients with abscesses in

grades C and D is significantly larger

if the number of prognostic signs is

higher. In addition, the percentage of

deaths correlated well with the num-

bem of prognostic signs.

DISCUSSIONThe radiologic features and role of

.� -. CT scanning in initial diagnosis of

acute pancreatitis and its complica-

tions are well established in the lit-

�- erature (8-18). The CT appearance of

clinical forms of mild (edematous, in-

terstitial) or severe (necrotizing, hem-

omnhagic) pancreatitis has been de-p scnibed (8, 19, 20). To our knowledge,

however, a comprehensive evalua-

tion of the prognostic value of the mi-.3 tial CT examination based on clinical

follow-up, surgical findings, and con-

S relation with prognostic signs has not

been performed. This study attempts

to fill this gap and establishes the val-

ue of CT scanning, not only in the

initial diagnosis of pancreatitis, but as

a prognostic indicator of the disease’s

severity and its expected complica-

tions.

Secondary CT Findings

Our search of the literature did not

disclose a previous assessment of the

secondary CT findings evaluated in

this study. Fatty infiltration of the liv-

en was seen in 21% of our patients

(Fig. 3) and occurred about equally in

patients with mild, moderate, or se-

vene pancreatitis. Gallbladders with

thickened walls were seen in five

cases (Fig. 5), and the significance is

unknown since the condition was

present in patients without clinical

evidence of cholecystitis. It may me-

present nonspecific edema associated

with alcoholic liver disease or non-

specific inflammation related to pan-

creatitis. Pleural effusions were larger

and more commonly seen in patients

with severe pancreatitis. In this series,

they were present in 65% of grade E

patients and in only 10% in grades A

and B. Bilateral pleural effusions were

seen almost exclusively in grade E pa-

tients. There was no correlation be-

tween the severity of pancreatitis and

its cause in this series. Five of the 11

cases of gallstone pancreatitis were

classified as grade E, while the other

six were grade A, B, or C.While acute pancreatitis is general-

ly considered a diffuse disease, in this

series a segmental form of pancreati-

tis was observed in 18.1% of the cases.

(Fig. 7). Specifically, the head of the

pancreas was enlarged in a larger pro-

portion of patients with gallstone

pancreatitis (27.3%), compared with

the proportion of the total series

(8.3%).

CT and Clinical Course

The survey of the statistical data

presented shows that a clear comrela-

tion can be established between the

severity of pancreatitis, as determined

at the initial CT examination, and the

clinical course. We noted a steady

trend toward an increased average

number of fasting days and days hos-

pitalized in patients with more severe

grades of pancreatitis (Table 3). Five

of six deaths and 88.8% of all abscesses

occurred in patients initially classi-

fied as having grades D and E pan-

creatitis. No patients originally classi-

fied as having grade A or B pan-

creatitis had subsequent abscesses. All

patients with a normal pancreas on

CT scan (grade A) had a mild clinical

course without complications and

were discharged in less than 2 weeks.

Although the clinical course was

consistent with the grade of pancrea-

titis, some grade A patients may not

have had pancreatitis at all. There-

fore, the exact percentage of patients

with acute pancreatitis and a normal

CT scan is difficult to assess. This per-

centage depends mainly on the sever-

ity of acute pancreatitis and the time

of the examination and should be ex-

pected to vary from series to series.

CT and Development ofAbscesses

A strong relationship exists be-

tween the initial presence of pemipan-

creatic fluid collections (grades D and

E) and the development of abscesses.

Abscesses occurred in 18 patients in

this series (21 .7%), but they developed

in only two patients without initial

fluid collections.

The presence of poorly encapsulat-

ed pemipancneatic fluid collections in

patients with acute pancreatitis

.4

4

“4

4

A

772 . Radiology September 1985

should not be regarded casually. Flu-

id collections resolved spontaneously

in 54.3% of patients who had them but

lingered on and eventually became

infected in the remaining 45.7%. Fol-

low-up CT examinations should be

performed in these patients to assess

the presence, size, and location of

these collections until they resolve.

Previously, extravasated pancreatic

secretions and the development of

large pemipancreatic fluid collections

were considered an escape mecha-

nism, leading to a beneficial decom-

pression of the pancreatic duct system

(12). In our study, however, based on

short-term CT and clinical follow-up

evaluation, we failed to detect any ad-

vantages of large fluid collections for

this group of patients. While we did

not conduct long-term evaluations,

we found that extravasated fluid was

associated with a protracted and se-

vene clinical course. In patients with-

out such fluid, the course of pancrea-

titis was mild or significantly shorten

and less complicated.

The diagnosis of abscess in most of

our cases was based on the presence

of a persistent fluid collection plus

sepsis unresponsive to antibiotic them-

apy. Because of debris and necrotic

tissue, the density of fluid collections

was variable (5-30 HU) and not help-

ful in this diagnosis. The roles of per-

cutaneous aspiration and drainage of

pancreatic abscesses have been me-

ported in the literature (21, 22), but

these procedures were not used in

this series.

Retmopemitoneal air was seen in four

patients, all of whom had proved ab-

scesses at surgery. As reported in the

literature (23, 24), fluid collections

containing air may develop secon-

damy to entemic fistulas and may not

always indicate an abscess. However,

this CT finding, particularly when

seen during the initial attack, strong-

ly suggests a gas-forming infection

and is extremely valuable in quickly

identifying this potentially life-

threatening complication. In three

patients, metropemitoneal aim visual-

ized on CT scan in the first 24 hours

led to a correct diagnosis that was not

suspected clinically. Surgery was per-

formed without delay, and all three

patients survived.

Prognostic Signs, CT, andClinical Course

The relationship between prognos-

tic signs and severity of pancreatitis is

documented in Table 2. Infected ab-

scesses occurred with an increased in-

cidence in patients with several prog-

nostic signs. Abscesses were seen in

80.0% of patients with six to eight

signs, compared with 12.5% of pa-

tients with zero to two signs. We

found that using prognostic signs and

CT findings led to a better estimation

of the risk of death in this series. In

grades A and B patients, none of the

patients died, regardless of the num-

ben of prognostic signs, which varied

between zero and five. On the other

hand, the mortality of patients initial-

ly classified as grades C, D, on E come-

lated with the increasing number of

prognostic signs (Table 5).

We conclude that initial CT exami-

nation in cases of acute pancreatitis is

very helpful in establishing on con-

firming the clinical diagnosis, as well

as in depicting associated abnonmali-

ties. CT can also be used as an early

indicator of the disease’s severity and

its expected morbidity and mortality.

We found a good correlation between

the grades of mild, moderate, or se-

vene pancreatitis as established by CT

appearance and the clinical course,

development of abscesses, and death.

The use of objective prognostic signs

with initial CT findings improves the

original prognostic estimation and

identifies patients in whom life-

threatening complications may devel-

op. CT examinations should be pen-formed in all patients with moderate

or severe clinical forms of pancreatitis

to evaluate the presence and severity

of the initial attack and to assess its

clinical evolution. U

Send correspondence and reprint requests to:Emil Balthazar, M.D., NYU Medical Center, Bel-levue Hospital, Department of Radiology, 27thStreet and 1st Avenue, New York, New York10016.

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