A Comparative Study of 511 keV SPECT and PET Using Separate 370 MBq F-18-FDG Doses on Different Days

All previously reported comparative studies of 511 keV single-photon emission computed tomography (SPECT) and positron emission tomography (PET) have used one fluorine-18-fluorodeoxyglucose (FDG) dose, followed by PET and SPECT on the same day. This approach is inherently biased against the second imaging study. Therefore, we prospectively compared conventional PET and 511 keV SPECT in 23 patients with proven malignancy using separate 370 MBq FDG doses on different days employing an ECAT 951/31R PET scanner and a Trionix XLT-20 for SPECT. Discrepancies were evident in twelve of 23 patients (52%). In eight of these (66%) findings were seen exclusively on PET and represented the only metabolic evidence of disease. Thirty-seven of the 52 lesions (71%) detected at PET were also defined by SPECT, most above 2 cm. In 4 cases of extrahepatic abdominal disease (3 colorectal, 1 melanoma), both PET and SPECT missed small recurrent omental and perivesical lesions; several lesions up to 1.2 cm were also missed by CT and MRI.     

Intraocular tumors: evaluation with MR imaging

Sixty-seven ocular tumors were studied with magnetic resonance (MR) imaging and computed tomography (CT). These tumors included primary uveal melanoma (n = 55), circumscribed choroidal hemangioma (n = 3), diffuse choroidal hemangioma (n = 1), retinal capillary hemangioma (n = 1), medulloepithelioma (n = 1), choroidal nevus (n = 1), retinoblastoma (n = 1), and choroidal metastases (n = 4). MR imaging demonstrated all these lesions, while CT demonstrated 88%. Associated retinal detachment was more easily distinguished from the neoplasms with MR imaging. Extrascleral extension of melanoma and hemorrhagic cystic necrosis within the melanoma were clearly demonstrated with MR imaging, but not with CT. Ninety-three percent of melanomas were markedly hyperintense, compared with the intensity of the vitreous body, on T1-weighted images and hypointense on T2-weighted images. All metastatic lesions were isointense on T1-weighted images and hypointense on T2-weighted images. The circumscribed choroidal hemangiomas were hyperintense on T1-weighted images and isointense on T2-weighted images. MR imaging is superior to CT in detection of intraocular tumors and may be more specific in diagnosis.     

Detectability of liver metastases in malignant melanoma: prospective comparison of magnetic resonance imaging and positron emission tomography

PURPOSE: We evaluated the diagnostic accuracy of magnetic resonance imaging (MRI) and positron emission tomography (PET) for detection of liver metastases in malignant melanoma. MATERIAL AND METHODS: Thirty-five patients with 39 combined unenhanced MRI and fluorine-18 deoxyglucose (F-18 FDG) PET scans were prospectively studied. In discordant imaging findings final diagnosis was proven by clinical follow-up >6 months and demonstration of progressive liver metastases by at least one imaging method. Sensitivities and specificities were compared and the influence of lesion size and melanin content on diagnostic accuracy was determined. RESULTS: MRI and PET were concordantly negative for presence and number of liver metastases in 28 patients and positive in four patients. PET and MRI were false positive in one patient each. In one patient MRI showed a single metastases not seen by PET and in one patient MRI demonstrated more metastases at the first examination. In follow-up investigations MRI revealed more metastases than PET in both patients. The sensitivities for lesion detection were 47% (16/34) for PET and 100% for MRI. Lesion detectability by PET was related to lesion size (P < 0.0001) but not to melanin content. CONCLUSION: MRI is more sensitive in the detection of liver metastases in patients with malignant melanoma. Small lesions are easily missed by PET, while melanin content does not influence detectability by PET.     

Preliminary clinical assessment of dynamic 18F-fluorodeoxyglucose positron emission tomography/computed tomography for evaluating lymph node metastasis in patients with lung cancer: a prospective study

Annals of Nuclear Medicine - We assessed the diagnostic capacity of dynamic fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and dual-time-point...     

Intraocular metastases: differential diagnosis from uveal melanomas with high-resolution MRI using a surface coil

Magnetic resonance imaging with dedicated surface coils plays a pivotal role in differential diagnosis and staging of intraocular tumors. The purpose of this study was to establish MRI criteria for the differential diagnosis of uveal melanomas and intraocular metastases. In a prospective study 44 eyes in 36 patients with intraocular metastases and 200 patients with uveal melanomas were investigated with MRI using a 1.5-T scanner and a 5-cm surface coil. Both quantitative and qualitative evaluation of the resulting images was performed. The MR signal intensities typically expected for metastases (slightly hyperintense on non-contrast T1-weighted images and hypointense on T2-weighted images compared to the vitreous body) were seen in only 23.1%. The typical melanoma signal of either moderate or strong hyperintensity on T1-weighted images and hypointensity on T2-weighted images was seen in 69.4% of the proven melanomas. Contrast enhancement was observed in both metastases and melanomas. Morphological differences between metastases and melanomas were detected in tumor size, shape, position, frequency of retinal detachment, and homogeneity of the tumor. Differentiation between intraocular metastases and uveal melanoma is limited by overlap of signal intensities. Some improvement is achieved with morphologic criteria.     

Hepatic metastases studied with MR and CT

Examinations of the liver using magnetic resonance (MR) and computed tomography (CT) were performed on 50 patients with hepatic metastases. MR and CT were comparable in their ability to detect metastases, which generally appeared hypointense compared with normal liver parenchyma on T1-weighted MR images and hyperintense on T2-weighted images. The MR imaging techniques that were most reliable in detecting metastases were inversion recovery and a relatively T2-weighted, spin-echo technique (TR = 1,500 msec, TE = 60 msec). We conclude that CT, because of its shorter imaging time, greater spatial resolution, and lower cost, should remain the preferred screening test for hepatic metastases. MR imaging should be reserved for patients with equivocal CT findings and for patients in whom there is persistent clinical suspicion of hepatic metastases despite a negative CT examination.     

A variety of appearances of malignant melanoma in the head: a review.

Imaging is frequently requested to evaluate patients with malignant melanoma for metastases. When melanoma metastasizes to the head, the lesions can have a variety of appearances and can occur in a variety of locations. The usual appearances of malignant melanoma on magnetic resonance images include the melanotic and amelanotic patterns. The melanotic pattern consists of high signal intensity on T1-weighted images and low signal intensity on T2-weighted images. In the amelanotic pattern, the lesion is hypointense or isointense to the cortex on T1-weighted images and hyperintense or isointense to the cortex on T2-weighted images. However, there is frequent deviation from these patterns. Other patterns include small and rapidly growing metastases, miliary metastases, and subependymal metastases. Although the brain is the most common site of metastases to the head from melanoma, melanoma can metastasize to almost any intracranial or extracranial structure. Structures in the head that can be involved by metastases from melanoma include bone, muscle, the nasopharynx and mucosa, the parotid gland, the meninges, the choroid plexus, the internal auditory canal, and the orbit. The radiologist needs to be aware of these varied appearances and the relatively ubiquitous sites of involvement to better detect these lesions.     

A seldom case of primary urethral malignant melanoma and breast cancer detected by (18)F-FDG PET/CT

In the 1(st )issue of HJNM for 2012 we read with interest a case where 3 different cancers were detected. Synchronous second malignancy can be incidentally detected in routine fluorine-18-fluoro-deoxy-glucose positron emission tomography/computed tomography ( (18)F-FDG PET/CT) imaging in approximately 1% of cancer patients with lungs being the most frequent site. We report the (18)F-FDG PET/CT scan for staging of the primary malignant melanoma of the urethra and for the detection of another malignancy in the breast in the same patient, since primary malignant melanoma of urethra is very seldom. A 65 years old post-menopausal woman presented with increased frequency of micturition, dysuria and a gradually enlarging mass protruding from the external urethral meatus. Fine needle aspiration cytology (FNAC) performed from the mass revealed malignant melanoma. On cystourethrescopy examination, a 4x4 cm blackish mass was noted at the external urethral meatus with a satellite nodule in the bladder trigone. Contrast enhanced CT (CeCT) of the pelvis showed soft tissue thickening along the urethra infiltrating urinary bladder neck and vagina. Analysis of (18)F-FDG PET/CeCT was performed to assess the extent of the disease. Intensely (18)F-FDG avid soft tissue mass (SUV(max): 20.1) was noticed along the entire length of the urethra with hypermetabolic right inguinal and left external iliac lymph nodes. In addition to (18)F-FDG uptake in the bladder wall and the vaginal wall, intense (18)F-FDG uptake was also seen in two soft tissue nodules in the right breast and in the axillary lymph nodes suggestive of a second primary in the breast. Cytological diagnosis of intraductal breast carcinoma was made after FNAC from the breast nodule. Urethral melanoma was treated with anterior exenteration and ileal conduit. Histopathology confirmed the diagnosis of primary malignant melanoma of urethra infiltrating the urinary bladder and anterior vaginal wall. Postoperative histopathology from the right inguinal and left external iliac lymph nodes revealed metastatic disease. The diagnostic contribution of PET/CT was crucial. Melanotic melanoma cells have a distinctive MRI signal, which may be helpful in diagnosis. In this case whole body MRI could have been of equal value for accurate staging of urethral melanoma, but whole body MRI is a cumbersome procedure and often is not practical. Primary urethral carcinoma is very rare and an annual ageadjusted incidence rate of 4.3 per 106 in males and 1.5 per 106 in females has been reported in USA. Primary malignant melanoma of the urethra is rare, representing less than 1% of all melanomas and 4% of urethral cancers. Furthermore, the incidence of two primary cancers is rare and is reported to be between 0.3% and 4.3%. Primary malignant melanoma of the urethra has a worse prognosis than its cutaneous counterpart, partly due to delayed diagnosis. At the time of diagnosis, urethral melanoma is usually deeply invasive and locally extended to the vagina or vulva or the corpora cavernosa. Inguinal lymph node metastases are present at diagnosis in half of the cases and distant metastases in one third of them. Positron emission tomography demonstrates specificity and accuracy of 94.7% and 73% respectively in detecting lymph nodal metastases. Sensitivity, specificity and accuracy of (18)F-FDG PET/CT in detecting metastases in high risk patients were 85%, 96%, 91% while for (18)F-FDG PET/CT with dedicated CT interpretation were 98%, % and 96%, respectively. Recently, the role of (18)F-FDG PET/CT in treatment response evaluation of melanoma patients has also been demonstrated. Incidental (18)F-FDG uptake in the breasts is rare, and the lesion may be malignant in up to 57% of the cases. To our knowledge no published literature is available on synchronous breast carcinoma and urethral melanoma. The reason why some patients are more prone to develop multiple cancers remains obscure. One possibility may be of a genetic predisposition linking the two cancers. Research suggests that mutations in CDKN2A, a gene that indicates high risk of developing melanoma, also puts carriers at an up to 3.8 times greater risk of breast cancer. Similarly, mutations in the gene of breast cancer susceptibility, BRCA2, increase carriers' risk of melanoma by as much as 2.58 times. In conclusion, we describe a case of two primary carcinomas: a unique urethral malignant melanoma and a breast carcinoma, detected and staged by (18)F-FDG PET/CT.     

Visceral metastases from melanoma: findings on MR imaging.

Typical ocular and CNS melanomas are hyperintense on T1-weighted MR images and hypointense on T2-weighted MR images. We performed MR imaging in 48 patients with melanoma metastatic to visceral organs. Images were reviewed retrospectively in order to determine whether there were predominant MR features specific for visceral melanoma and to see if visceral metastases have MR characteristics similar to metastases in the CNS. Eleven patients also were examined after injection of gadopentetate dimeglumine to evaluate the enhancement characteristics of these tumors. Two hundred sixty-one lesions were found. Lesions were classified according to their signal intensities relative to uninvolved liver on T1-weighted, T2-weighted, and short TI inversion recovery (STIR) pulse sequences. Most commonly, lesions were either hypointense or isointense on T1-weighted sequences and hyperintense on T2-weighted and STIR sequences (185 lesions). Less frequently, lesions were hyperintense on T1-weighted sequences and hypointense or isointense on T2-weighted and STIR sequences (59 lesions). A mixed pattern was seen on T1- and T2-weighted sequences in 17 lesions. The patterns did not correlate with lesion size. Of the three sequences studied by subjective comparison, the STIR sequence in our series had the highest sensitivity for lesion detection and yielded the highest lesion conspicuity. Injection of gadopentetate dimeglumine in 11 patients did not increase either the number or the conspicuity of lesions seen. Our results show that visceral metastases from melanoma have a wide variety of appearances on MR images. The STIR sequence appears to be optimal, and the metastases do not enhance with gadopentetate dimeglumine.     

Primary and metastatic breast carcinoma: initial clinical evaluation with PET with the radiolabeled glucose analogue 2-[F-18]-fluoro-2-deoxy-D-glucose

The authors assessed whether breast cancers can be detected by means of positron emission tomography (PET) with the positron-emitter-labeled glucose analogue 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG). In 12 patients with primary and/or metastatic breast cancer, PET images of F-18 distribution in vivo were obtained approximately 1 hour after intravenous injection of 10 mCi of FDG. Scan findings were correlated with other imaging data and physical examination and biopsy results. Ten of 10 primary breast cancers were imaged by means of FDG PET with a tumor:background FDG uptake ratio of 8.1 (median). Ten of 10 bone metastases were imaged with a tumor:normal bone uptake ratio of 6.05 (median). Five of five known soft-tissue metastases and four previously unsuspected nodal lesions were found with PET. No false-positive foci of FDG uptake were demonstrated. In two cases with negative mammograms due to dense breast parenchyma, FDG PET clearly delineated the primary tumors. These preliminary data demonstrate the feasibility and substantial potential of PET scanning with FDG to detect and localize both primary and metastatic breast cancers.     

Fluor-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in malignant melanoma. Diagnostic comparison with conventional imaging methods

Purpose: To assess the diagnostic value of fluor-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in screening for melanoma metastases.Material and Methods: The case records of 94 melanoma patients who had been examined by whole-body FDG-PET between 1995 and 1999 were evaluated retrospectively. Forty patients showed evidence of lymphogenous and 42 of hematogenous metastasis. The maximal interval between PET and the diagnostic procedure under comparison was 2 weeks. Confirmation of the findings was based on histology or the clinical or radiological course.Results: In 24 patients, all diagnostic examinations including CT had been performed within 2 weeks from PET. In no case did PET change the staging. In 13 patients, PET agreed with morphological diagnosis in the number of metastatically invaded organs. This included 3 patients without metastases. The estimated number of organs invaded by metastases was higher with PET in 5 patients and higher with morphological imaging techniques in 6 patients. Among the PET findings with higher or equivocal counts of organs with metastases there were 2 confirmed false-positive findings.Conclusion: In a selected patient population, FDG-PET was found to be inferior to CT for diagnosing lung and liver metastases. The supplementary use of FDG-PET is not generally of value once metastasis has been established.     

MR imaging of hepatic metastasis in patients with malignant melanoma: evaluation of suspected lesions screened at contrast-enhanced CT

Purpose

To evaluate the magnetic resonance (MR) imaging feature of suspected hepatic metastasis in patients with malignant melanoma which showed intermediate findings on screened contrast-enhanced computed tomography (CECT).

Materials and methods

MR imaging was performed in 38 patients (22 men, 16 women; mean age, 58 years) whose CECT findings were intermediate. Hepatic metastases had been diagnosed on MR imaging in 23 of the 38 patients. Verification of hepatic metastasis was made by histological examination: ultrasonographic-guided needle biopsy (n = 3), autopsy (n = 3), and surgical resection (n = 1), or by an obvious progression in number and/or size of the lesions on follow-up MR imaging (n = 24). Two diagnostic radiologists reviewed MR images by consensus. The median follow-up duration was 14.2 months.

Results

Abnormal findings were detected in 31 patients on MR images, and undetected in the remaining seven patients resulting in false-positive on CECT. The mean size of the lesion was 11.0 mm. False-positive results were obtained in two lesions which disappeared on follow-up MR imaging. In six patients, lesions were considered as hepatic cysts on MR images. As a result, a total of 35 hepatic metastases were detected on MR images. Of these, 18 patients demonstrated typical melanotic appearance on MR images which showed shortened T1 and T2 relaxation times, and five patients demonstrated atypical melanotic appearance. In 16 patients, extra-hepatic metastases were also developed.

Conclusion

MR imaging could rule out hepatic metastasis in patients with malignant melanoma which showed intermediate findings on screened CECT, and could detect additional extra-hepatic metastases.     

Use of fluorine-18 fluorodeoxyglucose positron emission tomography in the detection of silent metastases from malignant melanoma

Correct staging is crucial for the management and prognosis of patients with malignant melanoma. The aim of this prospective study was to compare staging by whole-body positron emission tomography using fluorine-18 fluorodeoxyglucose (18F-FDG) with staging by conventional methods. Thirty-eight patients with malignant melanoma of clinical stage II (local recurrence, in-transit and regional lymph node metastases) or III (metastases to other sites than in stage II) were included in the study. The results of the PET scans were compared with those obtained by clinical examination, computed tomography, ultrasound, radiography, and liver function tests and histology or clinical follow-up. With 18F-FDG PET we found for all foci a sensitivity of 97% and a specificity of 56%, compared with 62% and 22%, respectively, when using routine methods. For intra-abdominal foci, the sensitivity and specificity were 100% for both 18F-FDG PET and routine methods. Corresponding figures for pulmonary/intrathoracic foci were 100% and 33%, respectively. Of the patients included in this study, 34% would not have been staged correctly by conventional methods alone. We conclude from this study that 18F-FDG PET is a sensitive method superior to conventional methods for detecting widespread metastases from malignant melanoma. Mutilating surgery of no benefit can thereby be avoided. 18F-FDG PET is useful as a supplement to clinical examination in melanoma staging.     

Retrospective review: usefulness of a number of imaging modalities including CT, MRI, technetium-99m pertechnetate scintigraphy, gallium-67 scintigraphy and F-18-FDG PET in the differentiation of benign from malignant parotid masses

Objective The aim of this study is to evaluate an imaging approach using computed tomography (CT), magnetic resonance imaging (MRI), technetium-99m pertechnetate scintigraphy (^99mTc pertechnetate scintigraphy), gallium-67 scintigraphy (⁶⁷Ga scintigraphy) and fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET). Material and Methods We reviewed retrospectively 59 patients with parotid masses. CT, MRI,⁶⁷Ga scintigraphy,^99mTc pertechnetate scintigraphy, and¹⁸F-FDG PET were performed. Results All of the benign tumors had smooth margins on CT and MRI. Patients with inflammatory lesions and malignant lesions showed well-defined margins or ill-defined margins. All Warthin's tumors showed high technetium accumulation. Many of malignant tumors showed high FDG accumulation. Both pleomorphic adenomas and Warthin's tumors showed high accumulation in some cases on¹⁸F-FDG PET. Among 15 patients with pleomorphic adenoma, 14 patients showed marked hyperintensity relative to CSF on T2-weighted images and partial enhancement on contrast-enhanced T1-weighted images. Combination of several imaging modarity offered usefulness of differential diagnosis for parotid masses. Conclusion An efficient combination of imaging methods may be helpul for achieve the correct diagnosis.     

Metastatic brain lesions may demonstrate photopenia on FDG-PET

Metastatic brain lesions generally demonstrate hypermetabolic foci on fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) images. A large area of photopenia of the brain on FDG-PET is most likely consistent with a benign etiology. The author reports 2 cases of cerebral metastases from lung cancers, which display complete photopenia on FDG-PET. The brain is a special organ with high background uptake on PET and significant cytotoxic edema surrounding the metastatic deposits. In some cases, it is a dilemma to identify malignant intracranial foci on PET. Anatomic imaging, for example, MRI or CT correlation is needed for proper interpretation of brain PET on evaluation of metastases.     

Evaluation of hemangioma by positron emission tomography: role in a multimodality approach

PURPOSE: The relative utility of various preoperative diagnostic imaging modalities for the evaluation of hemangioma of the extremities, including positron emission tomography (PET) (using 18F-fluoro-2-deoxy-D-glucose [FDG] and fluorine-18 alpha-methyltyrosine [FMT]), computed tomography (CT), magnetic resonance imaging (MRI), and digital subtraction angiography (DSA), was investigated. METHODS: Imaging findings in 16 patients with 16 histopathologically documented hemangiomas of the extremities were retrospectively reviewed. Preoperative imaging included: FDG-PET (n = 16), FMT-PET (n = 12), MRI (n =16), CT (n =11), and DSA (n =14). RESULTS: All 16 lesions examined by PET with FDG and/or FMT showed accumulation. The standardized uptake values (SUVs) for FDG-PET for the 16 examined tumors ranged from 0.7 to 1.67; for FMT-PET, they ranged from 0.14 to 1.00. The SUVs with both tracers indicated the benign nature of the tumor. Computed tomography demonstrated variable attenuation and phleboliths in two patients. The MRI signal characteristics were relatively consistent: heterogeneous signals were slightly higher than those of skeletal muscle on T1-weighted images and brighter than those of subcutaneous fat on T2-weighted images. The pooling and cotton-wool staining depicted in DSA was found to be significantly correlated with FDG accumulation, suggesting that localized blood retention-induced ischemia may accelerate anaerobic glycolysis, which leads to high FDG uptake. CONCLUSION: Although plain radiography, CT, MRI, and angiography may provide anatomic extent and be pathognomonic, FDG-PET and FMT-PET may be the most reliable among the studied imaging modalities for differentiating benign hemangiomas from other soft tissue tumors, especially malignant neoplasms.     

Imaging features of primary and recurrent esophageal cancer at FDG PET.

Because of the poor prognosis for patients with esophageal cancer and the risks associated with surgical intervention, accurate staging is essential for optimal treatment planning. Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) is a useful adjunct to more conventional imaging modalities in this setting. FDG PET is not an appropriate first-line diagnostic procedure in the detection of esophageal cancer and is not helpful in detecting local invasion by the primary tumor, and further studies are required to determine its efficacy in the detection of local nodal metastases. However, FDG PET is superior to anatomic imaging modalities in the ability to detect distant metastases. Metastases to the liver, lungs, and skeleton can readily be identified at FDG PET. In addition, FDG PET has proved valuable in determining the resectability of disease and allows scanning of a larger volume than is possible with computed tomography. Recurrent disease is readily diagnosed and differentiated from scar tissue with FDG PET. In addition, FDG PET may play a valuable role in the follow-up of patients who undergo chemotherapy and radiation therapy, allowing early changes in treatment for unresponsive tumors. The management of most patients with esophageal cancer can be improved with use of FDG PET.     

PET/CT and MRI of intra-osseous haemangioma of the tibia

Intra-osseous haemangioma is a rare, benign neoplasm that usually involves the vertebrae and craniofacial bones. Furthermore, its occurrence in the long bones is extremely rare. We report the findings of fluorine-18-fludeoxyglucose ((18)F-FDG) positron emission tomography (PET)/CT and MRI in a patient with intra-osseous haemangioma in the proximal tibia, who was initially misdiagnosed as having a malignancy based on (18)F-FDG PET/CT. (18)F-FDG PET/CT showed a well-marginated osteolytic lesion with abnormal FDG uptake. The mass demonstrated low signal intensity on T(1) weighted MRI. On T(2) weighted images, the lesion appeared as a cluster of high signal intensity lobules and showed strong enhancement on contrast-enhanced T(1) weighted images. Surgical curettage was performed and histopathological examination of the excised tissue confirmed a cavernous haemangioma.     

Diagnostic accuracy of <Superscript>18</Superscript> F-FDG-PET and PET/CT in patients with Ewing sarcoma family tumours: a systematic review and a meta-analysis

Objective  

To systematically review and meta-analyse literature data on the diagnostic performance of fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) and positron emission tomography/computed tomography (PET/CT) in patients with Ewing sarcoma family tumours (ESFT).     

MRI of carcinoid tumors: spectrum of appearances in the gastrointestinal tract and liver

The purpose of this study was to evaluate the spectrum of appearances of gastrointestinal carcinoid tumors at magnetic resonance imaging (MRI) and to elucidate patterns of appearances of carcinoid liver metastases on precontrast and postgadolinium images. The MR examinations of 29 patients (11 men, 18 women; age range, 33-87 years) with histologically confirmed gastrointestinal carcinoid tumors, representing our complete 9.5 years of experience with this entity, were retrospectively reviewed. Twelve patients had MR examinations prior to resection or biopsy of the primary tumor (preoperative group); 17 patients were imaged postsurgically (postoperative group). All MR studies were performed at 1.5 T and comprised T1-weighted spoiled gradient echo (SGE), T2-weighted fat-suppressed turbo spin echo, HASTE, and serial postgadolinium T1-weighted SGE sequences without and with fat suppression. Morphology, signal intensity, and contrast enhancement of primary tumors and of metastases to the mesentery, peritoneum, and liver were evaluated. Primary tumors were visualized in 8 of 12 patients and best demonstrated on postgadolinium T1-weighted fat-suppressed images. The appearance of primary tumors was a nodular mass originating from the bowel wall (4 of 12 patients) or regional uniform bowel wall thickening (4 of 12 patients) with moderate intense enhancement on postgadolinium images. In 4 of 12 patients the primary tumor was prospectively not seen. Mesenteric metastases, seen in eight patients, presented as nodular masses and were associated with mesenteric stranding in seven patients. A total of 156 liver metastases were evaluated in 16 patients. On precontrast T1- and T2-weighted images, 117 metastases (75%) were hypointense and hyperintense, respectively. A total of 146 metastases (94%) were hypervascular, showing moderate intense enhancement during the hepatic arterial phase, and 9 metastases (6%) were hypovascular. Twenty-three metastases (15%) were visible only on immediate postgadolinium images. MRI is able to demonstrate findings in carcinoid tumors, including the primary tumor, mesenteric metastases, and liver metastases. Liver metastases are commonly hypervascular and may be demonstrable only on immediate postgadolinium images.