Analysis of Mechanical Loading after Anatomic Anterior Cruciate Ligament Reconstruction Using Combined Single-Photon Emission Computerized Tomography and Conventional Computerized Tomography

PURPOSE: This study was to evaluate changes of the mechanical loading pattern after anatomic anterior cruciate ligament (ACL) reconstruction by analyzing uptake patterns using combined single-photon emission computerized tomography and conventional computerized tomography (SPECT/CT). MATERIALS AND METHODS: On SPECT/CT, high signal intensity of the articular surface which shows biological activity and mean increase of mechanical loading was compared with that of the tibiofemoral shaft as a comparative signal. The proportion of positive signals was evaluated in all compartments of the operated knee. Analysis was performed according to combined injury. RESULTS: A relatively high proportion of positive signals was detected in the posterior zone of the lateral tibial plateau (23.5%) and trochlear groove (23.5%) although increased signal intensity was detected in all compartments. There was no statistical difference depending on the presence of combined injury and between single-bundle and double-bundle ACL reconstruction. CONCLUSIONS: Following anatomic ACL reconstruction, higher signal intensity was detected, particularly in the posterior part of the lateral tibial plateau and trochlear groove. Close observation for further signal changes or osteoarthritic changes would be required even if there was no combined injury and anatomic reconstruction was performed.

Practical Use of Bone Scan in Patients with an Osteoporotic Vertebral Compression Fracture

Rib fractures are one of main causes of chest or flank pain when related to an osteoporotic vertebral compression fracture (OVCF). The authors investigated the incidence and risk factors of rib fracture in 284 patients with OVCF using bone scans and evaluated the feasibility as to whether bone scans could be utilized as a useful screening tool. Hot uptake lesions on ribs were found in 122 cases (43.0%). The factors analyzed were age, sex, number and locations of fractured vertebrae, BMD, and compression rates as determined using initial radiography. However, no statistical significances were found. In 16 cases (5.6%), there were concurrent multiple fractures of both the thoracic and lumbar spines not detected by single site MRI. Sixty cases (21.1%) of OVCF with the a compression rate of less than 15% could not be identified definitely by initial plain radiography, but were confirmed by bone scans. It is concluded that a bone scan has outstanding ability for the screening of rib fractures associated with OVCF. Non-adjacent multiple fractures in both thoracic and lumbar spines and fractures not identified definitely by plain radiography were detected on bone scans, which provided a means for determining management strategies and predicting prognosis.

Practical Use of Bone Scan in Patients with an Osteoporotic Vertebral Compression Fracture

Rib fractures are one of main causes of chest or flank pain when related to an osteoporotic vertebral compression fracture (OVCF). The authors investigated the incidence and risk factors of rib fracture in 284 patients with OVCF using bone scans and evaluated the feasibility as to whether bone scans could be utilized as a useful screening tool. Hot uptake lesions on ribs were found in 122 cases (43.0%). The factors analyzed were age, sex, number and locations of fractured vertebrae, BMD, and compression rates as determined using initial radiography. However, no statistical significances were found. In 16 cases (5.6%), there were concurrent multiple fractures of both the thoracic and lumbar spines not detected by single site MRI. Sixty cases (21.1%) of OVCF with the a compression rate of less than 15% could not be identified definitely by initial plain radiography, but were confirmed by bone scans. It is concluded that a bone scan has outstanding ability for the screening of rib fractures associated with OVCF. Non-adjacent multiple fractures in both thoracic and lumbar spines and fractures not identified definitely by plain radiography were detected on bone scans, which provided a means for determining management strategies and predicting prognosis.

Medical Image Retrieval: Past and Present / 대한의료정보학회지

With the widespread dissemination of picture archiving and communication systems (PACSs) in hospitals, the amount of imaging data is rapidly increasing. Effective image retrieval systems are required to manage these complex and large image databases. The authors reviewed the past development and the present state of medical image retrieval systems including text-based and content-based systems. In order to provide a more effective image retrieval service, the intelligent content-based retrieval systems combined with semantic systems are required.

Review of Semantically Interoperable Electronic Health Records for Ubiquitous Healthcare / 대한의료정보학회지

In order to provide more effective and personalized healthcare services to patients and healthcare professionals, intelligent active knowledge management and reasoning systems with semantic interoperability are needed. Technological developments have changed ubiquitous healthcare making it more semantically interoperable and individual patient-based; however, there are also limitations to these methodologies. Based upon an extensive review of international literature, this paper describes two technological approaches to semantically interoperable electronic health records for ubiquitous healthcare data management: the ontology-based model and the information, or openEHR archetype model, and the link to standard terminologies such as SNOMED-CT.

Radiopharmaceuticals Used in Cardiac Imaging / 핵의학분자영상

Many radiopharmaceuticals have been developed and wildy used in the imaging cardiac function. Myocardial perfusion imaging (MPI) is a well established noninvasive method of assessing coronary blood flow and has been widely used in patients diagnosed or suspected with coronary artery diseases. The innovation of radiopharmaceuticals used in the cardiac imaging is one of the most important contributors to the development of nuclear cardiology. Thallium-201 and various technetium-99m agents have been globally used for myocardial perfusion SPECT, and N-13 ammonia (13NH3), rubidium-82 (82Rb), O-15 water (H215O) for myocardial perfusion PET. As well as the cardiac perfusion studies, new radiopharmaceuticals that visualize fat metabolism or receptors of the sympathetic nervous system have successfully been applied to clinical practice. Useful information can be obtained for diagnosing coronary artery disease, evaluating patients' condition, or assessing therapeutic effects. In this review, we describe the characteristics and clinical usefulness of radiopharmaceuticals used for cardiac SPECT and PET.

Added Value of 3D Cardiac SPECT/CTA Fusion Imaging in Patients with Reversible Perfusion Defect on Myocardial Perfusion SPECT / 핵의학분자영상

PURPOSE: Integration of the functional information of myocardial perfusion SPECT (MPS) and the morphoanatomical information of coronary CT angiography (CTA) may provide useful additional diagnostic information of the spatial relationship between perfusion defects and coronary stenosis. We studied to know the added value of three dimensional cardiac SPECT/CTA fusion imaging (fusion image) by comparing between fusion image and MPS. MATERIALS AND METHODS: Forty-eight patients (M:F=26:22, Age: 63.3+/-10.4 years) with a reversible perfusion defect on MPS (adenosine stress/rest SPECT with Tc-99m sestamibi or tetrofosmin) and CTA were included. Fusion images were molded and compared with the findings from the MPS. Invasive coronary angiography served as a reference standard for fusion image and MPS. RESULTS: Total 144 coronary arteries in 48 patients were analyzed; Fusion image yielded the sensitivity, specificity, negative and positive predictive value for the detection of hemodynamically significant stenosis per coronary artery 82.5%, 79.3%, 76.7% and 84.6%, respectively. Respective values for the MPS were 68.8%, 70.7%, 62.1% and 76.4%. And fusion image also could detect more multi-vessel disease. CONCLUSION: Fused three dimensional volume-rendered SPECT/CTA imaging provides intuitive convincing information about hemodynamic relevant lesion and could improved diagnostic accuracy.

Evaluation of Myocardial Oxygen Consumption with 11C-Acetate and 3D PET/CT: By Applying Recirculation Correction Method and Modified One-Compartmental Tracer Kinetic Modeling / 핵의학분자영상

PURPOSE: We intended to evaluate myocardial oxygen consumption (MVO2) by applying recirculation correction and modified one-compartment model to have a reference range of MVO2 in normal young population and to reveal the effect of recirculation on time-activity curve (TAC). Materials and METHODS: In nine normal male volunteers with mean age of 26.3+/-4.0, MVO2 was estimated with 925 MBq (25mCi) of 11C-Acetate (Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Korea) and PET/CT (Biograph 6, Siemens Medical Solution, Germany). Analysis software such as MATLAB(R) v7.1 (Mathworks, Inc., United States), Excel(R) 2007 (Microsoft, United States), and SPSS(R) v12.0 (Apache Software Foundation, United States) were used. Twenty three frames were of 12 x 10, 5 x 60, 3 x 120, 2 x 300's duration, respectively. The modified one-compartmental model and the recirculation correction method were applied. Statistical analysis was performed by using Test of Normality, ANOVA and Post-Hoc (Scheffe's) analysis, and p-value less than 0.05 was considered as significant. RESULTS: The normal reference ranges of MVO2 were presented as 3.18-4.64 x 10(-4) ml/g/sec, 1.91-3.94 x 10(-4) ml/g/sec, 4.31-6.40 x 10(-4) ml/g/sec, 2.84-4.53 x 10(-4) ml/g/sec and 3.42-5.00 x 10(-4) ml/g/sec in the septum, the inferior wall, the lateral wall, the anterior wall and the entire wall, respectively. In addition, it was noted that the dual exponentiality of the clearance curve is due to the recirculation effect and that the characteristic of the curve is essentially mono-exponential. CONCLUSION: 11C-Acetate is a radiotracer worthwhile to assess MVO2. Re-circulated 11C can influence TAC of 11C in myocadia and so the recirculation correction must be considered when measuring MVO2.

Erratum: Bone scan appearance and biochemical markers of the bone metabolism in hemodialysis patients / 대한내과학회지

No abstract available.

Diagnostic Performance of Combined Single Photon Emission Computed Tomographic Scintimammography and Ultrasonography Based on Computer-Aided Diagnosis for Breast Cancer / 핵의학분자영상

PURPOSE: We investigated whether the diagnostic performance of SPECT scintimammography (SMM) can be improved by adding computer-aided diagnosis (CAD) of ultrasonography (US). MATERIALS AND METHODS: We reviewed breast SPECT SMM images and corresponding US images from 40 patients with breast masses (21 malignant and 19 benign tumors). The quantitative data of SPECT SMM were obtained as the uptake ratio of lesion to contralateral normal breast. The morphologic features of the breast lesions on US were extracted and quantitated using the automated CAD software program. The diagnostic performance of SPECT SMM and CAD of US alone was determined using receiver operating characteristic (ROC) curve analysis. The best discriminating parameter (D-value) combining SPECT SMM and the CAD of US was created. The sensitivity, specificity and accuracy of combined two diagnostic modalities were compared to those of a single one. RESULTS: Both SPECT SMM and CAD of US showed a relatively good diagnostic performance (area under curve = 0.846 and 0.831, respectively). Combining the results of SPECT SMM and CAD of US resulted in improved diagnostic performance (area under curve =0.860), but there was no statistical differerence in sensitivity, specificity and accuracy between the combined method and a single modality. CONCLUSION: It seems that combining the results of SPECT SMM and CAD of breast US do not significantly improve the diagnostic performance for diagnosis of breast cancer, compared with that of SPECT SMM alone. However, SPECT SMM and CAD of US may complement each other in differential diagnosis of breast cancer.

Bone scan appearance and biochemical markers of the bone metabolism in hemodialysis patients / 대한내과학회지

BACKGROUND: The gold standard for a diagnosis of ROD is performing a bone biopsy. We need other non-invasive diagnostic techniques because of this procedure's invasiveness. In this study, we evaluated the value of a radionucleotide bone scan and the various biochemical markers for determining the bone metabolism in hemodialysis patients . METHODS: This study evaluated 118 hemodialysis patients who underwent 99mTc-MDP bone scanning and blood tests for such biochemical markers as osteocalcin and c-terminal telopeptide of type I collagen. Two nuclear medicine physicians read the bone scan images semi-quantitatively for six bone areas and the soft tissue, and they assigned a score of 0, 1 or 2 to the findings. RESULTS: The patients were categorized into 3 classes: iPTH or =200 pg/mL. For the group with a iPTH > or =200 pg/mL, the Ca, P product, alkaline phophatase and osteocalcin levels were increased, and the serum aluminum level was decreased compared to the other groups. When the bone scans were analyzed, the sum of the bone uptake scores was higher in the group with an iPTH > or =200 pg/mL while the soft tissue uptake score was higher in the group with an iPTH <50 pg/mL. The most common type of patient was a patient with an iPTH <50 pg/mL, and adynamic bone disease may be the most prevalent type of ROD. CONCLUSIONS: The bone scan findings correlated with the iPTH level in hemodialysis patients. Bone scans can provide additional information if this is combined with other biological markers. We stillneed to confirm its usefulness by conducting a comparative study with using bone biopsy.

A Static Scintigraphy for Imaging Aspiration Using Semi-Solid Food / 핵의학분자영상

PURPOSE: Aspiration scintigraphy is a procedure of nuclear imaging to evaluate aspiration and of quantifying the amount of aspirate. The ultimate goal of our study is to define the correlation between aspiration and aspiration pneumonia by aspiration scintigraphy, and this is a preliminary report of its trial. MATERIALS AND METHODS: Ten patients with positive findings by videofluoroscopy were selected. The patients ingested semi-solid food containing Tc-99m tin colloid 92.5 MBq (2.5 mCi) and images were acquired immediately after the ingestion and 3 hrs later. A fraction of aspiration to the ingested was calculated using an equation with a decay correction. RESULTS: Five patients were interpreted positive by aspiration scintigraphy. Four patients were positive at initial images and the fractions of aspiration were 0.11%, 0.11%, 0.81%, and 0.11%. The one patient who was shown aspirated at both images had initial 5.82% and delayed 2.26%. CONCLUSION: Aspiration scintigraphy enables us to localize the aspiration at any desired time of the test and to quantify its amount. Follow-up studies are warranted.

Multifocal Peritoneal Splenosis in Tc-99m-Labeled Heat-Denatured Red Blood Cell Scintigraphy / 핵의학분자영상

A 44-year-old man with a past medical history of splenectomy came to hospital because of epigastric pain. Abdominopelvic computed tomography(CT) showed a soft tissue mass and multifocal variable-sized nodules as well as findings suggestive of cholecystitis. Subsequently, he underwent Tc-99m-labeled heat-denatured red blood cell(RBC) scintigraphy to evaluate the mass and nodules. The scintigraphy confirmed multifocal peritoneal splenosis in the abdominopelvic cavity.

Reducing the Scan Time in Gastric Emptying Scintigraphy by Using Mathematical Models / 대한핵의학회잡지

PURPOSE: Gastric emptying scan (GES) is usually acquired up to 2 hours. Our study investigated whether a fraction of meal-retention in the stomach at 120 minutes (FR120) was predicted from the data measured for 90 minutes by using non-linear curve fitting. We aimed at saving the delayed imaging by utilizing mathematical models. MATERIALS AND METHODS: Ninety-six patients underwent GES immediately after taking a boiled egg with 74 MBq (2 mCi) Tc-99m DTPA. The patients were divided into Group I (T1/2 < or=90 min) and Group II (90 min< T1/2< or=120 min). Group I (n=51) had 21 men and 30 women, and Group II (n=45) 15 men and 30 women. There was no significant difference in age and sex between the two groups. Simple exponential, power exponential, and modified power exponential curves were acquired from the measured fraction of meal-retention at each time (0, 15, 30, 45, 60, 75, and 90 min) by non-linear curve fitting (MATLAB (R) 5.3) and another simple exponential fitting was performed on the fractions at late times (60, 75, and 90 min). A predicted FR120 was calculated from the acquired functional formulas. A correlation coefficient between the measured FR120 and the predicted FR120 was computed (MedCalc (R) 6.0). RESULTS: Correlation coefficients (r) between the measured FR120 and the predicted FR120 of each mathematical functions were as follows: simple exponential function (Group I: 0.8858, Group II: 0.5982, p< 0.0001), power exponential function (Group I: 0.8755, Group II: 0.6008, p< 0.0001), modified power exponential function (Group I: 0.8892, Group II: 0.5882, p< 0.0001), and simple exponential function at the late times (Group I: 0.9085, Group II: 0.6832, p< 0.0001). In all the fitting models, the predicted FR120 were significantly correlated with the measured FR120 in Group I but not in Group II. There was no statistically significant difference in correlation among the 4 mathematical models. CONCLUSION: In the cases with T1/2 < or=90 min, the predicted FR120 is significantly correlated with the measured FR120. Therefore, FR120 can be predicted from the data measured for 90 minutes by using non-linear curve fitting, saving the delayed imaging after 90 minutes when T1/2 < or=90 min is ascertained.

Useful Lateral Views of Sacrococcygeal Region in Skeletal Scintigraphy / 대한핵의학회잡지

A tail-on-detector (TOD) view has been used to see the symphysis pubis or sacrococcyx in skeletal scintigraphy, but it is inconvenient to acquire because a patient must sit or lean on a detector. The TOD views are still frequently performed in training hospitals in Korea, although it is becoming almost impossible to sit on a camera in this age of dual-headed cameras. The authors show cases with lateral views obtained in supine position that were acquired for the same reason; they are easier and more useful than the TOD views.

Development of an angiogenesis-focused cDNA chip and validation of its functionality

DNA chip has been used as a powerful tool to study the genetic reprogramming of cells and its link to cellular phenotype such as angiogenesis. To evaluate the angiogenesis related genetic reprogramming more efficiently, we here developed an angiogenesis- focused cDNA chip containing 153 angiogenesis related genes arrayed in duplicate on a slide glass. In order to validate the functionality of the angiogenesis-focused cDNA chip, we examined gene expression profiles in HT1080 cells treated with either fetal bovine serum, a well known pro-angiogenic factor, or trichostatin A, a known angiogenesis inhibitor, using the cDNA chip. All duplicate data from the analysis are well matched with each other and gene expression profiles are well consistent with previously reported data. These results demonstrate that the angiogenesis-focused cDNA chip developed here can be a useful tool towards angiogenesisrelated researches.

Diagnostic Accuracy of Quantitative Scintimammography Using Tc-99m Tetrofosmin according to ROC Curve Analysis for Breast Cancer / 한국유방암학회지

PURPOSE: Tc-99m Tetrofosmin is a new alternative to Tc- 99m MIBI for nuclear breast imaging. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the feasibility of Tc-99m Tetrofosmin quantitative scintimammography (SMM) (qSMM) and to compare with previously reported Tc-99m MIBI qSMM data [J Kor Surg 1999;57(5):638-644)]. METHODS: Prone anterior, lateral planar and supine SPECT images were taken from 135 cases in 131 female patients (mean ages=44 yr) with breast mass (size> or =0.2 cm) after 30mCi intravenous injection of Tc-99m Tetrofosmin. 70 malignant and 65 benign lesions were histologically proven. Three regions of interest (ROIs) were drawn over designated areas: the Lesion (L), the Normal breast opposite the lesion (NL) and the right Chest wall (CW). L/NL and L/CW ratios on both the SPECT and the planar images were analyzed. RESULTS: ROC curve analysis revealed that the planar L/NL ratio and the SPECT L/NL and L/CW ratios had higher diagnostic accuracy for detecting breast cancer than he planar L/CW ratio did (P<0.05). The qSMM (mean), which is an arithmetic mean of the planar L/NL ratio, the SPECT L/NL ratio and the SPECT L/CW ratio, the sensitivity, the specificity, accuracy and area under curve (AUC) were 82.9%, 81.5%, 82.2% and 0.879 respectively. Presence of axillary lymph node metastasis showed a slightly higher qSMM (mean) value (2.79 {n=23} vs 2.75 {n=27} P=0.06). These are comparable with previously reported Tc-99m MIBI qSMM data of 84.4%, 76.6%, 81.0% and 0.847 respectively, and the presence of axillary lymph node metastasis showed a higher qSMM(mean) value (4.09 {n=17} vs 3.09 {n=28}, P=0.06) [J Kor Surg 1999; 57(5):638-644)]. CONCLUSION: Tc-99m Tetrofosmin qSMM (mean) is a useful and objective method for differentiating malignant from benign breast lesion and has the comparable diagnostic accuracies of Tc-99m MIBI qSMM.

Evaluation of Endothelium-dependent Myocardial Perfusion Reserve in Healthy Smokers: Cold Pressor Test using H2 (15) O PET / 대한핵의학회잡지

PURPOSE: Much evidence suggests long-term cigarette smoking alters coronary vascular endothelial response. In this study, we applied nonnegative matrix factorization (NMF), an unsupervised learning algorithm, to CO-less H2 (15) O-PET to investigate coronary endothelial dysfunction caused by smoking noninvasively. MATERIALS AND METHODS: This study enrolled eighteen young male volunteers consisting of 9 smokers (23.8 +/- 1.1 yr; 6.6 +/- 2.5 pack-years) and 9 nonsmokers (23.8 +/- 2.9 yr). They do not have any cardiovascular risk factor or disease history. Myocardial H2 (15) O-PET was performed at rest, during cold (5degrees C) pressor stimulation and during adenosine infusion. Left ventricular blood pool and myocardium were segmented on dynamic PET data by NMF method. Myocardial blood flow (MBF) was calculated from input and tissue functions by a single compartmental model with correction of partial volume and spillover effects. RESULTS: There were no significant difference in resting MBF between the two groups (Smokers: 1.43 0.41 ml/g/min and non-smokers: 1.37 +/- 0.41 ml/g/min; p = NS). during cold pressor stimulation, MBF in smokers was significantly lower than that in non-smokers (1.25 +/- 0.34 ml/g/min vs 1.59 +/- 0.29 ml/g/min ; p=0.019). The difference in the ratio of cold pressor MBF to resting MBF between the two groups was also significant (p=0.024; 90 +/- 24% in smokers and 122 +/- 28% in non-smokers.). During adenosine infusion, however, hyperemic MBF did not differ significantly between smokers and non-smokers (5.81 +/- 1.99 ml/g/min vs 5.11 +/- 1.31 ml/g/min ; p=NS). CONCLUSION: In smokers, MBF during cold pressor stimulation was significantly lower compared with nonsmokers, reflecting smoking-induced endothelial dysfunction. However, there was no significant difference in MBF during adenosine-induced hyperemia between the two groups.

Accumulation and Aberrant Modifications of alpha-Crystallins in Anterior Polar Cataracts

Crystallins are the major proteins found in the lens, and the localization of specific crystallins is well known. Overexpression and accumulation of alphaB-crystallin has been observed in response to stress conditions or in certain diseases, such as brain tumors and neurodegenerative diseases. The purpose of this study was to examine whether alpha-crystallins are modified during pathological myofibroblastic changes in lens epithelial cells. Lens epithelial cells attached to the anterior capsules of patients with nuclear or anterior polar cataracts were analyzed quantitatively for alpha-crystallin proteins and mRNAs using Western blot and RT-PCR analysis., respectively. The degree of modification of alpha-crystallins was determined by 2-dimensional gel electrophoresis followed by Western blotting. Higher molecular weight protein bands that were immunoreactive to anti-alphaA- and anti-alphaB-crystallin antibodies around 45 kDa accumulated more in the anterior polar cataract samples than in those with the nuclear type of cataracts. Also monomeric alphaB-crystallins accumulated more in lens epithelial cells of patients with anterior polar cataracts. By comparison, no significant changes were found in the levels of the mRNAs encoding alphaA- and alphaB-crystallins in the different types of cataracts. Both alphaA- and alphaB-crystallin proteins seemed to undergo more extensive modification in anterior polar cataracts. Conclusion. In addition to fibrotic changes, which accompany increased levels of extracellular matrix molecules, accumulation and abnormal modification of alpha-crystallins might be implicated in the pathogenic mechanism of this type of cataract.

Clinical Value of Whole Body F-18 FDG PET in The Management of Recurrent Colorectal Malignancy / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The aim of this study was to evaluate the clinical value of whole body 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in the patient with a recurrence of a previously treated colorectal malignancy. MATERIALS AND METHODS: Fifty-eight cases were scanned using PET at the PET Center of Seoul National University Hospital between May 1995 and Aug 2002. All the patients had had a previous operation for a colorectal malignancy. The PET scans were performed for the following reasons: - investigation of a recurrence (n=12), investigation of the operability (n=38) and clinical follow up (n=8). In these 58 cases, 47 of the CT scans and 55 of the CEA (Carcinoembryonic antigen) were checked prior to the FDG- PET. The accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the PET scans were calculated, and compared with those of conventional CT scan and CEA, which were also compared with the previous reported data. Eight cases, whose managements were influenced by the PET findings, were analyzed. RESULTS: Recurrences, or metastases, of colorectal cancer developed in 51 cases, with 49 of these being detected by the PET. The accuracy, sensitivity and specificity of the PET were 96.6 (56/58), 96.1 (49/51) and 100% (7/7), respectively. The PPV and NPV of the PET were 100 (49/49) and 77.8% (7/9), respectively. The accuracy and sensitivity of the PET were higher than those of the CT (85.1 and 88.1%), with the differences being statistically significant (p-value 0.001 and 0.003, respectively). CONCLUSION: It is concluded that a FDG-PET scan is a more accurate and sensitive diagnostic tool than a CT scan for the detection of a recurrence or metastasis in a colorectal malignancy. In addition, a FDG-PET may alter the management of patients with recurrent colorectal cancer. Therefore, it is recommended that a PET should be considered when a tumor recurrence is suspected during conventional follow up.