Miklós Papós

The possible role of F-18 FDG positron emission tomography in the differential diagnosis of focal pancreatic lesions

Purpose To compare the diagnostic values of different methods for the differentiation of malignant from benign pancreatic lesions. Methods In 22 patients with focal pancreatic lesions, the carbohydrate antigen (CA) 19-9 level was measured; abdominal ultrasound (US), computed tomography (CT), endoscopic retrograde cholangiopancreatography (ERCP), and F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) were performed; and the value of these methods were analyzed for their use in cancer diagnosis. Results Malignant lesions were identified in six patients and verified by surgery or clinical follow-up. The CA 19-9 level was elevated in four of the five patients examined (sensitivity, 80%). In all six cases, US and CT revealed hypoechogenic and hypodense areas (sensitivity, 100%). In one patient, ERCP was unsuccessful but yielded true-positive results in three others (sensitivity, 60%). The sensitivity of FDG PET was 100%. Sixteen focal cases of pancreatic disease proved to be benign. The CA 19-9 level was elevated in four of them (specificity, 73%). Hypoechogenic and hypodense areas were evident on US and CT in eight patients. The specificity of CT was 50% (8 of 16 cases). The specificity of US was 47% (7 of 15 cases). The specificity of successful ERCP was 92%. Fourteen negative FDG-PET results were truly negative. In two patients, however, the PET findings proved to be falsely positive (specificity, 88%). Conclusions FDG-PET is an effective tool to differentiate malignant from benign focal pancreatic lesions. In persons with focal pancreatic hypoechogenic or hypodense lesions detected by CT or US and an elevated CA 19-9 level, FDG PET should be the next step in the diagnostic strategy.

Clinical value of technetium-99m-HMPAO-labeled leukocyte scintigraphy and spiral computed tomography in active Crohn's disease

Clinical value of technetium-99m-HMPAO-labeled leukocyte scintigraphy and spiral computed tomography in active crohns disease

HM-PAO-labeled leukocyte scintigraphy in pediatric patients with inflammatory bowel disease

Leukocyte scintigraphy (LS) was performed in 20 pediatric patients with inflammatory bowel disease (IBD: 10 with ulcerative colitis, 2 with indeterminate colitis, and 8 with Crohn disease) in different stages of clinical activity. Leukocytes were separated from 15 to 60 ml venous blood and were labeled in vitro with [99mTc]HM-PAO. The segmental extent (small intestine; ascending, transverse, and descending colon; and recto-sigmoideum) of the process was determined by LS. The uptake of each bowel segment was scored in relation to the bone marrow uptake. The scintigraphic activity, calculated by summing the segment scores, was compared with laboratory parameters. The mean labeling efficacy was 76% (60-86%). The segmental extent of the process determined by LS was compared with the results of barium enema or colonoscopy with regard to 32 bowel segments. The sensitivity, specificity, and accuracy of LS were 93, 88, and 91%, respectively. Two extraintestinal manifestations (abdominal abscess and joint involvement) were also detected by LS. These lesions were verified by computed tomography (CT) (abscess) and on the basis of the clinical outcome (arthritis). The scintigraphic activity correlated with the C-reactive protein (CRP) level (r = 0.82, p < 0.001), the alpha 2-globulin level (r = 0.63, p < 0.02), the sedimentation rate (r = 0.51, p < 0.05), and the fS iron level (r = -0.66, p < 0.005). LS is applicable in pediatric patients. The method is an excellent technique for assessment of the extent of IBD in children. Extraintestinal manifestations of IBD can also be investigated by LS. The scintigraphic activity is a useful parameter for determination of the activity of IBD in children.

Anti-granulocyte immunoscintigraphy and [99mTc]hexamethylpropyleneamine-oxime-labeled leukocyte scintigraphy in inflammatory bowel disease

A prospective study was carried out on 13 patients with ulcerative colitis and 11 with Crohns disease to compare the value of radioimmunoscintigraphy involving99mTc-labeled antigranulocyte monoclonal antibody (BW 250/183) with that of hexamethylpropyleneamine-oxime-labeled leukocyte scintigraphy. The extent of the process (various segments of the small bowel; ascending, transverse, and descending colon; and rectosigmoideum) was determined in 115 segments by means of radioimmunoscintigraphy and leukocyte scintigraphy and compared with the results of enteroclysis and colonoscopy in 64 segments. The scintigraphic activity, calculated by summing the segment scores, was compared with clinical and laboratory parameters. During radioimmunoscintigraphy, the 24-hr fecal excretion of the antibody was measured. The two methods revealed a different extent of the process (P<0.01). The segmental sensitivity and specificity were 63% and 96% in radioimmunoscintigraphy, and 87% and 94% in leukocyte scintigraphy. Leukocyte scintigraphy proved to be superior in cases with small intestine involvement, but the methods are of similar value in cases with large bowel involvement. The scintigraphic activity determined by radioimmunoscintigraphy and the fecal excretion of monoclonal antibody correlated with seven parameters, while that determined by leukocyte scintigraphy did so with 12 variables. Both methods are of similar value for the detection of large bowel involvement, but leukocyte scintigraphy was the better method for determination of the involved segments in the small intestine. The scintigraphic activity proved a useful parameter, correlating well with the clinical and laboratory variables.

Technetium-99m hexamethylpropylene amine oxime labelled leucocyte scintigraphy in ulcerative colitis and Crohn's disease

Technetium-99m hexamethylpropylene amine oxime labelled leucocyte scintigraphy (LS) was performed on 45 occasions in 30 patients with ulcerative colitis and on 53 occasions in 34 patients with Crohns disease. Serial images were taken following re-injection of the labelled leucocytes. The segmental extent of the inflammation and the grade of the leucocyte uptake were calculated, and compared with the laboratory results and colonoscopy findings. The sensitivity and specificity of LS proved higher in ulcerative colitis (87% and 93%) than in Crohns disease (53% and 89% in cases with large intestine involvement, and 82% and 100% in cases with small intestine involvement). The activity of the process determined by LS correlates with the α2 globulin level (r=0.47), fibrinogen level (r=0.50), fS iron level (r=−0.57), sedimentation (r=0.44), leucocyte count (r=0.38), platelet count (r=0.34) and Best index (r=0.31) in ulcerative colitis, but not in Crohns disease.

Prognostic role of 99mTc-HM-PAO-leukocyte scintigraphy in acute pancreatitis and in patients with pancreatic pseudocysts

Fifty-five leukocyte scintigraphies were performed. Thirty-five patients (group 1) with acute pancreatitis in the early phase and 20 patients (group 2) with pancreatic chronic pseudocysts following acute pancreatitis were tested. The clinical features, laboratory parameters, and Ranson classifications were registered during hospitalization. In group 1, most of the cases with a severe clinical outcome gave positive leukocyte scintigraphic results (10/12). Leukocyte accumulation was also detected in patients with mild acute pancreatitis (4/23), but at a lower frequency. In the acute phase, significant differences in laboratory parameters (sedimentation rate and leukocyte count) were found in the leukocyte scintigraphy-positive versus -negative cases. The scintigraphic activity correlated with the sedimentation rate, leukocyte count, fever, and duration of hospitalization. In group 2 there were five cases with a positive leukocyte scan. A pancreatic abscess was found in four of them during surgery. In seven patients with a normal scintigram, surgery revealed a noninfected pancreatic pseudocyst. Leukocyte infiltration of the pancreas can be demonstrated by leukocyte scintigraphy. A positive leukocyte scan indicated a severe course of acute pancreatitis. The method also seems useful for differentiation between infected and noninfected chronic pancreatic pseudocysts.

Tc-99m HMPAO leukocyte and Tc-99m nanocolloid scintigraphy in posttraumatic bone infection

Posttraumatic osteomyelitis was investigated in 23 patients using nuclear medicine techniques. Tc-99m hexamethylpropilene amine oxime (HMPAO)-labeled leukocyte scintigraphy was performed in 11 patients, and Tc-99m nanocolloid scanning was performed in the other 12 patients. The scintigraphic findings were compared with clinical, laboratory, radiologic, and bacteriologic results. The findings on leukocyte imaging were consistent with the clinical symptoms in 7 of 11 patients, with the laboratory pattern in 7 of 10 patients, with the radiologic findings in 7 of 11 patients, and with the results of bacteriology in 6 of 7 patients. The findings on nanocolloid scintigraphy corresponded with the clinical symptoms in 9 of 12 patients, with the laboratory pattern in 8 of 10 patients, with the radiologic findings in 8 of 12 patients, and with the bacteriology in 4 of 5 patients. The results suggest that both methods were of similar value for the detection of chronic posttraumatic osteomyelitis regardless of whether the process was active. Conversely, on the basis of semiquantitative analysis of the images, leukocyte scintigraphy seemed to characterize the grade of inflammation better than did nanocolloid scintigraphy.

Validation of CT doses of SPECT/CT and PET/CT hybrid devices: Lessons learned

The aim of the study was to check the validity of computed tomographic (CT) doses exhibited by SPECT/CT and PET/CT hybrid devices. Dose measurements were taken from four SPECT/CT and four PET/CT cameras commercially available from different manufacturers. A calibrated ionization chamber was placed in whole-body or head phantoms for the acquisition of CT images with clinically used parameters. Computed tomography dose index (CTDIvol) values were calculated according to the IEC 60601-2-44:1999 formula. The measured CTDIvol doses were compared with those preprogrammed by the manufacturer. In the case of the whole-body phantom, the differences between the measured and displayed values varied between −31 and +24% [European document RP162 (2012) sets up the limit for acceptance criterion as ±20%]. The head phantom data showed either an agreement between −10 and +24%, or an underestimation by two-fold. The latter seemed to be because, while preprogramming the doses, the manufacturer had used the whole-body phantom instead of a proper head phantom. The results of the work demonstrate the need for individual dosimetric calibration of every single X-ray tube. Dosimetric checks should be included in the regular quality control programmes of the SPECT/CT and PET/CT devices. Special attention should be paid to head-and-neck and paediatric protocols, in which the use of a head phantom is recommended for dose calibration.

Leukocyte labeling with 99mTc-HMPAO. The role of the in vitro stability of HMPAO on the labeling efficacy and image quality

Abstract 99m Tc-HMPAO was prepared by incubating for different times (range of 7–90 min) and was then used for in vitro leukocyte labeling. The effects of the variation of incubation time and cell concentration in the labeling suspension on the yield of the lipophilic complex, the labeling efficacy and the image quality were determined. The yield of lipophilic complex decreased with an increase of incubation time ( r = −0.5335). A weak correlation was observed between the incubation time and the labeling efficacy ( r = −0.2275) and between the lipophilic complex yield and the labeling efficacy ( r = −0.1960). The cell concentration in the labeling suspension appeared to be the most important factor affecting the labeling efficacy ( r = −0.4996). Variation of incubation time did not exert a change in quality of the images. The 99m Tc-HMPAO kit containing a stabilizing agent can be used for multiple leukocyte labeling after incubation for 7–90 min.

An Isotope-Diagnostic Approach to Erdheim-Chester's Disease of the Heart

Erdheim-Chesters disease is a form of histiocytic granulomatosis afflicting the skeletal system and various inner organs. Apart from incidental findings of involvement of various structures and tissues, a complete diagnostic workup to evaluate afflicted bodily parts is not known. The authors we present several specific isotope-diagnostic techniques of a case to support the identification of this rare multisystem infiltrative disease.