2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography in primary extranodal lymphomas: treatment response evaluation and prognosis.

BACKGROUND: We evaluated the role of [18F]FDG PET/CT in tumor response assessment and prognosis of primary extranodal lymphoma (PEL) patients. METHODS: We examined retrospectively, 56 PEL patients: 31 with aggressive diffuse large B cell lymphoma (DLBCL) and 25 with indolent lymphoma (20 mucosa-associated lymphoid tissue lymphoma and five follicular lymphoma). All patients had undergone [18F]FDG PET/CT at diagnosis (PET-I) and 50 of them also after therapy (PET-II). Moreover, 52 patients were subjected to a mean follow-up period of 76 months. RESULTS: PET-I was positive in 50 (89%) patients (mean SUVmax 10.3±6.7). In the assessment of tumor response, according to Lugano classification, 45 patients showed complete metabolic response (CMR), four patients had partial metabolic response (PMR) and one had progressive metabolic disease (PMD). Based on 66% ΔSUVmax cut-off, among CMR patients, 41 showed a ΔSUVmax>66% whereas among non-responders, four patients showed a ΔSUVmax<66%. At follow-up, univariate analysis showed that age, performance status, prognostic index, ΔSUVmax and Lugano classification predicted progression-free survival (PFS) (P<0.05), while, performance status, prognostic index, ΔSUVmax and Lugano classification predicted overall survival (OS) (P<0.05). At multivariate analysis only Lugano classification was retained in the model for prediction of both PFS (P<0.05) and OS (P<0.05). By Kaplan-Meier analysis and log-rank testing both PFS and OS were significantly better in patients in CMR as compared to patients in PMR or PMD according to Lugano classification (P<0.01). CONCLUSIONS: [18F]FDG PET/CT represents a useful tool in the detection of disease response and in the evaluation of outcome in PEL patients.

C-reactive protein levels are associated with paraoxonase polymorphism L55M in patients undergoing cardiac SPECT imaging.

BACKGROUND: Oxidation and inflammation are linked processes playing an important role in the development and progression of coronary artery disease (CAD). The relation between oxidation and inflammation markers with myocardial ischemia is still controversial. We assessed the association between paraoxonase (PON) polymorphisms (rs854560, rs662, rs7493) and high sensitivity C-reactive protein levels with stress-induced ischemia in patients with suspected CAD. MATERIALS AND METHODS: Patients (n = 203; 78 men; mean age 59 ± 10 years), with suspected CAD underwent on the same day stress/rest Tc-99m sestamibi cardiac single-photon emission computed tomography and venous blood samples collection, to assess PON polymorphisms, lipid profile and high sensitivity C-reactive protein levels. RESULTS: At cardiac tomography, 43 (21%) patients had stress-induced myocardial ischemia and 160 (79%) did not. At logistic regression analysis, diabetes (p < 0.005), sex (p = 0.020) and high-density lipoprotein (HDL)-cholesterol levels (p < 0.050) were independently associated with stress-induced ischemia. No differences of PON1 and PON2 genotype frequencies were observed between patients with and without stress-induced ischemia. Multiple linear regression analysis showed that LL genotype for PON1 (p < 0.03), high body mass index (BMI) values (p < 0.001) and low HDL-cholesterol levels (p < 0.05) are associated with high C-reactive protein levels independently from presence of stress-induced ischemia, age, sex, diabetes, hypertension, statin therapy, smoking and total cholesterol levels. CONCLUSIONS: The results of this study identified a weak association between the M55L polymorphism in PON1 gene and C-reactive protein levels. BMI showed a major role in the determination of C-reactive protein levels. No association between PON polymorphisms and stress-induced ischemia was found.

Recent Advances in Nuclear Imaging of Receptor Expression to Guide Targeted Therapies in Breast Cancer.

Breast cancer remains the most frequent cancer in women with different patterns of disease progression and response to treatments. The identification of specific biomarkers for different breast cancer subtypes has allowed the development of novel targeting agents for imaging and therapy. To date, patient management depends on immunohistochemistry analysis of receptor status on bioptic samples. This approach is too invasive, and in some cases, not entirely representative of the disease. Nuclear imaging using receptor tracers may provide whole-body information and detect any changes of receptor expression during disease progression. Therefore, imaging is useful to guide clinicians to select the best treatments for each patient and to evaluate early response thus reducing unnecessary therapies. In this review, we focused on the development of novel tracers that are ongoing in preclinical and/or clinical studies as promising tools to lead treatment decisions for breast cancer management.

18F-FDG PET/CT, 99mTc-MIBI, and MRI in evaluation of patients with multiple myeloma.

UNLABELLED: New imaging techniques have been introduced to assess the extent and severity of disease in multiple myeloma (MM) patients. The aim of our study was to compare newer imaging modalities-such as (18)F-FDG PET/CT, (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) scintigraphy, and MRI-to assess their relative contribution in the evaluation of MM patients at diagnosis. METHODS: Thirty-three newly diagnosed patients with MM were prospectively studied. Diagnosis and staging were made according to standard criteria. All patients underwent whole-body (18)F-FDG PET/CT, whole-body (99m)Tc-MIBI, and MRI of the spine and pelvis within 10 d, and imaging findings were compared. RESULTS: (18)F-FDG PET/CT was positive in 32 patients (16 focal uptake, 3 diffuse uptake, 13 focal and diffuse uptake), (99m)Tc-MIBI was positive in 30 patients (6 focal, 11 diffuse, 13 focal and diffuse uptake), and MRI of the spine and pelvis was positive in 27 patients (6 focal, 13 diffuse, 8 focal and diffuse uptake). (18)F-FDG PET/CT showed a total of 196 focal lesions (178 in bones and 18 in soft tissues), of which 121 were in districts other than the spine and pelvis, whereas (99m)Tc-MIBI visualized 63 focal lesions (60 in bones and 3 in soft tissues), of which 53 were in districts other than the spine and pelvis. In the spinal and pelvic regions, (18)F-FDG PET/CT detected 75 focal lesions (35 in spine and 40 in pelvis), (99m)Tc-MIBI visualized 10 focal lesions (1 in spine and 9 in pelvis), and MRI detected 51 focal lesions (40 in spine and 11 in pelvis). CONCLUSION: In whole-body analysis, (18)F-FDG PET/CT performed better than (99m)Tc-MIBI in the detection of focal lesions, whereas (99m)Tc-MIBI was superior in the visualization of diffuse disease. In the spine and pelvis, MRI was comparable to (18)F-FDG PET/CT and (99m)Tc-MIBI in the detection of focal and diffuse disease, respectively. Because myelomatous lesions may often occur out of spinal and pelvic regions, MRI should be reserved to the evaluation of bone marrow involvement of these districts, whereas (18)F-FDG PET/CT can significantly contribute to an accurate whole-body evaluation of MM patients. Finally, whole-body (99m)Tc-MIBI, despite its limited capacity in detecting focal lesions, may be an alternative option when a PET facility is not available.

Metastasis to the Sellar/Suprasellar Region in a Patient With Endometrial Carcinoma Detected by 18F-FDG PET/CT.

Metastases to pituitary gland, suprasellar region or skull base from endometrial carcinoma are an extremely rare occurrence. We report the case of a 77-year-old woman with metastasis to the sellar/suprasellar region from endometrial carcinoma revealed by F-FDG PET/CT and confirmed by subsequent CT and MRI of the brain. This case highlights the usefulness of a whole-body imaging methodology such as F-FDG PET/CT in the detection of distant and/or atypical sites of metastasis therefore being of help in guiding towards the correct diagnosis.

Prognostic role of FDG PET/CT in patients with differentiated thyroid cancer treated with 131-iodine empiric therapy.

BACKGROUND: To assess the long-term prognostic value of F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in patients with differentiated thyroid carcinoma (DTC) undergoing empiric radioiodine (RAI) therapy due to raising values of thyroglobulin (Tg). METHODS: Forty-nine patients with histological diagnosis of DTC (31 with papillary and 18 with follicular carcinoma) follow-up for a mean period of 7.9 ±â€Š5 years after empiric RAI therapy were retrospectively analyzed. RESULTS: FDG-PET/CT was negative in 15 (30.6%) patients and positive in 34 (69.4%), whereas postradioiodine therapy whole body scan (t-WBS) was negative in 16 (32.7%) and positive in 33 (67.3%) patients. FDG-PET/CT and t-WBS were in agreement in 32 patients (7 both negative and 25 both positive); on the contrary, in 17 patients there was disagreement between FDG-PET/CT and t-WBS (P =ns). At short-term follow-up, Tg normalized in 19 (38.8%) patients and was unchanged or increased in 30 (61.2%). Of the 15 patients with negative FDG-PET/CT, 11 (73.3%) showed Tg normalization, whereas of the 34 patients with positive FDG-PET/CT, only 8 (23.5%) had Tg normalization (χ =8.9, P < .005). At multivariate analysis, FDG-PET/CT and Tg normalization at short-term follow-up were independent predictors of disease-free survival (χ =26.3, P < .0001), while Tg normalization was the only variable associated with overall survival χ =7.2, P < .01). CONCLUSION: FDG-PET/CT in association with Tg normalization at short-term follow-up may be useful for long-term prognostic stratification in DTC patients.

Functional imaging of multidrug resistance in breast cancer.

Intrinsic or acquired multidrug resistance is the major cause of treatment failure in many human cancers. Multiple cellular mechanisms may contribute to the development of multidrug resistance including overexpression of P-glycoprotein (Pgp). The use of 99mTc-labeled lipophilic cations, which are transport substrate of Pgp, raised the possibility to predict the tumor response to treatment and to identify patients who will become refractory to subsequent therapy. Among these agents, 99mTc-MIBI is the most widely evaluated tracer and may serve as a paradigm of this class of compounds. In particular, many studies have shown the prognostic value of 99mTc-MIBI scan in different types of malignancy including breast cancer and the correlation with the expression of Pgp. However, additional mechanisms of cell resistance, mainly involving alterations of apoptosis, may also affect 99mTc-MIBI uptake in tumors. In particular, overexpression of the anti-apoptotic protein Bcl-2 prevents tumor cells to enter apoptosis and inhibits tracer accumulation into mitochondria. Therefore, while an absent or reduced early tracer uptake in large breast carcinomas reflects the existence of a defective apoptotic program, an enhanced tracer clearance in 99mTc-MIBI positive lesions reflects the activity of drug transporters such as Pgp. The existence of two different mechanisms underlying the predictive role of 99mTc-MIBI scan may be important to establish whether individual patients may benefit from Pgp inhibitors or Bcl-2 antagonists.

Detection of Leptomeningeal Involvement by 18F-FDG-PET/CT in a Patient With Non-Hodgkin Lymphoma.

Leptomeningeal infiltration of the brain or spinal cord by neoplastic cells may occur as complication of solid or hematopoietic tumors such as non-Hodgkin lymphoma. Previously rare, this event is becoming increasingly common as newer therapies can prolong survival but may not achieve therapeutic concentration in the central nervous system. Although prognosis is poor, early diagnosis and aggressive treatment may lead to prolonged survival and/or improvement of quality of life. We report a case of a 69-year-old man with leptomeningeal infiltration by non-Hodgkin lymphoma revealed by F-FDG-PET/CT and confirmed by subsequent spinal MRI and cerebrospinal fluid cytology.

Multimodal imaging with (18)F-FDG-PET/CT and (111)In-Octreotide SPECT in patients with metastatic medullary thyroid carcinoma.

OBJECTIVE: The aim of our study was to determine the role of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG-PET/CT) and indium-111 Octreotide single photon emission tomography ((111)In-Octreotide SPECT) in the evaluation of metastatic medullary thyroid carcinoma (MMTC). METHODS: Twenty-five MMTC patients were retrospectively evaluated. All patients had undergone whole-body (18)F-FDG-PET/CT including 20 who had also undergone (111)In-Octreotide SPECT within a maximum interval of 6 weeks. Diagnostic contrast-enhanced computed tomography (CT) alone or as part of (18)F-FDG-PET/CT examination was performed in all patients. RESULTS: Contrast-enhanced CT detected a total of 131 lesions including 79 enlarged lymph nodes and 14 bone lesions. (18)F-FDG-PET/CT visualized a total of 92 true positive lesions (SUVmax range 1.1-10.0, mean 4.0 ± 1.7) including 66 lymph nodes, 7 of which were not enlarged on CT, and 8 bone metastases. In the 20 patients studied with both techniques, a total of 64 and 46 true positive lesions were detected by (18)F-FDG-PET/CT and (111)In-Octreotide SPECT, respectively. In particular, (18)F-FDG uptake was found in 43 lymph nodes and in 7 bone metastases whereas (111)In-Octreotide uptake was detected in 27 lymph nodes and in 10 bone metastases. CONCLUSIONS: In MMTC patients, (18)F-FDG-PET/CT provides a useful contribution mainly in evaluating lymph node involvement whereas (111)In-Octreotide SPECT can contribute to the detection and somatostatin receptor characterization especially of bone lesions.

Prognostic role of 18F-FDG PET/CT in the postoperative evaluation of differentiated thyroid cancer patients.

PURPOSE: The aim of this study was to evaluate the role of F-FDG PET/CT performed after surgery but before radioiodine therapy in patients with differentiated thyroid cancer. PROCEDURES: FDG PET/CT was performed off l-thyroxine in 60 newly diagnosed differentiated thyroid cancer patients. Clinical and hematological evaluation as well as high-resolution neck ultrasound were performed. All patients underwent a complete follow-up (range, 6-67 months; mean [SD], 31.7 [20.6] months). The date of recurrence or the most recent office visit was recorded. Progression-free survival (PFS) is the primary end point of this study. Analysis was performed by Cox proportional hazards model. Survival curves were generated using Kaplan-Meier estimates, and the log-rank test was used to assess significance. RESULTS: FDG PET/CT was negative in 63% of patients, 20% had FDG thyroid bed uptake, 5% distant metastases, and 12% lymph node FDG uptake. In patients with positive FDG PET/CT scan (ie, those with distant metastases or lymph node uptake), a higher rate of recurrence was observed (50% vs 6%, P < 0.05). Thyroglobulin, neck ultrasound, stage, and FDG PET/CT correlated with PFS at univariate analysis. At multivariate analysis, only thyroglobulin and FDG PET/CT continued to be predictors of PFS. Patients with a negative FDG PET/CT scan have a better PFS either in the whole group or in those with elevated thyroglobulin level (both >2 ng/mL and >10 ng/mL). CONCLUSIONS: FDG PET/CT was abnormal in 17% of patients. Moreover, FDG PET/CT has an independent prognostic role, with a better PFS in patients with a negative scan.

18F-FDG PET/CT, 99mTc-MIBI, and MRI in the prediction of outcome of patients with multiple myeloma: a comparative study.

PURPOSE: The aim of this study was to compare the relative contribution of 18F-FDG PET/CT, 99mTc-MIBI, and MRI in predicting progression-free survival (PFS) and overall survival (OS) in multiple myeloma (MM) patients. PATIENTS AND METHODS: Thirty-three newly diagnosed MM patients had been evaluated in a previous study by 18F-FDG PET/CT, 99mTc-MIBI, and spine and pelvis MRI reporting focal lesions and diffuse bone marrow involvement. Twenty-seven patients were then subjected to a mean follow-up period of 58 months, whereas 6 patients were lost. RESULTS: 18F-FDG PET/CT, 99mTc-MIBI, and MRI were positive in 26, 24, and 22 patients, respectively, showing diffuse bone marrow involvement in 12, 21, and 17 patients and a total of 185, 56, and 39 focal lesions, respectively. At follow-up, 18 patients showed complete or partial remission, whereas 9 patients developed progressive disease, 7 of which died of myeloma. Univariate and subsequent multivariate analysis showed that F-FDG PET/CT focal uptake and Tc-MIBI focal and diffuse uptake predicted PFS (P = 0.0006), whereas 18F-FDG PET/CT focal uptake and 99mTc-MIBI focal uptake predicted OS (P = 0.0010). Although MRI diffuse pattern predicted PFS at univariate analysis (P = 0.0376), it was not retained in the model at multivariate analysis. Receiver operating characteristic curve analysis showed that the number of focal lesions best discriminating for PFS and OS prediction was 4 and 11 for 18F-FDG PET/CT and 2 in both cases for 99mTc-MIBI, respectively. By Kaplan-Meier analysis and log-rank testing, PFS and OS at follow-up were significantly better in patients showing a number of focal lesions at F-FDG PET/CT or Tc-MIBI lower than the respective cutoff (P = 0.03, P = 0.004, and P < 0.0001, respectively). Finally, PFS was significantly better in patients showing absent/faint diffuse Tc-MIBI uptake than in those having moderate/intense diffuse uptake (P = 0.0012). CONCLUSIONS: 18F-FDG PET/CT and 99mTc-MIBI may be useful in predicting PFS and OS in myeloma patients.

Determinants of physiologic 18F-FDG uptake in brown adipose tissue in sequential PET/CT examinations.

PURPOSE: The aim of this study was to assess independent predictors of 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) uptake in brown adipose tissue (BAT) in patients undergoing repeated positron emission tomography (PET)/computed tomography (CT) scans. PROCEDURES: Eight hundred forty-eight (mean age 50.9 ± 16 years) patients in whom PET/CT scan was repeated (mean interval 5 ± 1.5 months) constituted the study group. (18)F-FDG uptake in characteristic areas of BAT, with CT density of adipose tissue, greater than background soft-tissue activity was considered as evidence of BAT uptake. Both distribution and maximum standardized uptake values (SUVmax) were registered. Clinical and anamnestic data were collected for each patient. RESULTS: (18)F-FDG uptake in BAT was present in 8.6% patients at first scan. Independent predictors of presence of uptake were age (younger), gender (female), body mass index (lower), and maximum outdoor temperature (lower). Age was the only independent predictor of BAT (18)F-FDG uptake distribution, while SUVmax was related to both age and outdoor temperature. Independent determinants of persistence of BAT (18)F-FDG uptake at second PET/CT were outdoor temperature at time of second scan and extension of metabolically active BAT at first scan. CONCLUSIONS: Age, body mass index, and outdoor temperature are significant determinants of BAT evidence at (18)F-FDG PET/CT. Moreover, extension of BAT and outdoor temperature are the strongest determinants of persistence of BAT evidence on (18)F-FDG PET/CT in repeated scan.

PET/CT colonography in patients with colorectal polyps: a feasibility study.

PURPOSE: To examine: (1) the feasibility of PET/CT colonography (PET/CTc) in patients with colorectal polyps; (2) the impact of metabolic information on CTc interpretation and, conversely, the impact of morphological information on PET characterisation of focal colorectal uptake. METHODS: Ten patients with colorectal polyps underwent PET/CTc, followed within 3 h by therapeutic conventional colonoscopy (CC). A radiologist and a nuclear medicine physician analysed the PET/CTc images. The agreement of morphological and metabolic information in the colon and rectum was evaluated. The sensitivity and specificity of PET, CT and PET/CT were calculated for colorectal polyps. RESULTS: Seventeen polypoid lesions were identified at CC: six< or =5 mm, six between 6 and 9 mm, and five > or =10 mm (four hyperplastic polyps, 11 tubular adenomas, one adenocarcinoma and one submucosal lipoma). A total of 20 scans (supine and prone) were performed in the ten patients: the agreement of morphological and metabolic information was excellent in 17 scans, good in two and moderate in one. PET/CTc showed a sensitivity of 91% for lesions > or =6 mm and a specificity of 100%. The metabolic information did not disclose any further polyps missed on CTc. The morphological information permitted correct classification of all eight instances of focal radiotracer uptake. CONCLUSION: PET/CTc is a feasible study. Adding a colonographic protocol to PET/CT images seems to allow correct characterisation of all cases of colorectal focal radiotracer uptake. The metabolic information does not seem to increase the accuracy of CTc.

Sestamibi and FDG-PET scans to support diagnosis of jaw osteonecrosis.

Osteonecrosis of the maxillary or mandibular bone is an infrequent but often severe event occurring in patients who undergo prolonged treatment with bisphosphonates. Histology is in some cases mandatory to differentiate it from neoplastic osteolysis, but a biopsy can further contribute to bone damage. Functional imaging obtained by a tracer that shows oncotropic properties, such as Tc99m-sestamibi, in comparison to a non-tumor-specific substance such as FDG-PET, can support the differential diagnosis, thus avoiding invasive procedures. Four patients affected by multiple myeloma and jaw osteonecrosis were prospectively evaluated by sestamibi and FDG-PET scans. Local diagnosis was performed by clinical, radiological and, in some cases, histological evaluations. Each patient was studied by Tc99m-sestamibi, performed by planar anterior and posterior whole-body scans and SPECT of the head and neck, and by PET/CT. Two nuclear medicine physicians, unaware of the final diagnosis, reviewed the images. No sestamibi uptake was evident in the four patients with jaw osteonecrosis, while FDG-PET/CT showed focal uptake in all of them. Our study suggests that the combined use of sestamibi scintigraphy and FDG-PET/CT could support the clinical diagnosis of oral osteonecrosis avoiding the risks of a surgical biopsy. Studies on higher number of patients are necessary to validate these preliminary observations.

Short-term outcome of differentiated thyroid cancer patients receiving a second iodine-131 therapy on the basis of a detectable serum thyroglobulin level after initial treatment.

PURPOSE: The aim of this study was to evaluate the usefulness of high-dose 131I therapy administered only on the basis of raised serum Tg levels. METHODS: Among patients treated with total or near-total thyroidectomy and 131I ablation, 76 (54 women and 22 men) with differentiated thyroid cancer (41 with follicular and 35 with papillary cancer) showed a detectable (i.e. >1.5 ng/ml) serum Tg level on L: -thyroxine therapy during follow-up and were included in the study. In these patients, a further 131I therapy was scheduled (range 3.7-9.25 GBq, mean 6.087+/-1.705). Five to seven days after this radioiodine therapy, patients underwent 131I post-therapy whole-body scan (131I t-WBS). The serum Tg value at 12 months after 131I therapy was evaluated as an indicator of short-term response to radioiodine. RESULTS: At evaluation after 12 months, 21 (27.6%) of the 76 patients had a Tg value < or =1.5 ng/ml, 12 (15.8%) showed a Tg decrease of at least 50%, 22 (29%) had only a minor decrease in Tg (<50%) and 21 (27.6%) did not show any decrease in Tg. 131I t-WBS was positive in 52 patients (68%, group A) and negative in 24 (32%, group B). Normalisation of Tg was observed in 15 patients (29%) of group A and in six patients (25%) of group B. Overall, 23 (44%) patients of group A and ten (42%) of group B showed a > or =50% decrease in the Tg. Of the 52 patients of group A, 19 (36%) had local recurrence at 131I t-WBS, 18 (35%) showed lung involvement and 15, (29%) bone metastasis. On a patient basis, two (13%) of 15 patients with bone metastases, six (33%) of 18 patients with lung involvement and seven (37%) of 19 patients with local recurrence had Tg values at follow-up of < or =1.5 ng/ml (p NS). Overall, seven (37%) patients with local recurrence, eight (44%) with lung involvement and eight (53%) with bone metastases showed a > or =50% decrease in Tg. CONCLUSION: The findings of the present study suggest that the administration of therapeutic 131I only on the basis of elevated Tg levels has a definite therapeutic effect, at least in the short term. In addition, the possibility of obtaining a post-therapeutic 131I WBS can lead to better strategy definition for these patients.

Tc99m-sestaMIBI uptake in nonsecretory multiple myeloma.

Staging and monitoring of multiple myeloma (MM) is mainly based on monoclonal component quantification; the absence of such a parameter renders difficult follow up of patients with nonsecretory MM (nsMM). In this study our aims were to determine the specificity and sensitivity of Tc99m-sestaMIBI scintigraphy at diagnosis and during follow up of nsMM patients. Nine nsMM patients were prospectively studied at diagnosis and during treatment for a mean time of 33 months (range: 12-65+). Tc99m-sestaMIBI (MIBI) scintigraphy was compared to conventional imaging (CI: X ray with CAT or NMR details) at diagnosis and during follow up. At diagnosis, CI and MIBI were concordant in three patients; CI showed more focal lesions than MIBI in four patients, while MIBI revealed more focal lesions than CI in two patients. During the follow up, MIBI uptake was normal in the four patients who achieved remission. Five patients did not achieve remission: CI and MIBI were concordant in three, while MIBI was falsely negative in two patients. In conclusion, Tc99m-sestaMIBI scintigraphy has high sensitivity (no false positive cases) and 78% specificity (2/9 false negative cases) in tracing active nsMM lesions; it should be considered complementary to CI for monitoring this rare disease.