Bayesian penalized likelihood PET reconstruction impact on quantitative metrics in diffuse large B-cell lymphoma.

Evaluate the quantitative, subjective (Deauville score [DS]) and reader agreement differences between standard ordered subset expectation maximization (OSEM) and Bayesian penalized likelihood (BPL) positron emission tomography (PET) reconstruction methods. A retrospective review of 104 F-18 fluorodeoxyglucose PET/computed tomography (CT) exams among 52 patients with diffuse large B-cell lymphoma. An unblinded radiologist moderator reviewed both BPL and OSEM PET/CT exams. Four blinded radiologists then reviewed the annotated cases to provide a visual DS for each annotated lesion. Significant (P < .001) differences in BPL and OSEM PET methods were identified with greater standard uptake value (SUV) maximum and SUV mean for BPL. The DS was altered in 25% of cases when BPL and OSEM were reviewed by the same radiologist. Interobserver DS agreement was higher for OSEM (>1 cm lesion = 0.89 and ≤1 cm lesion = 0.84) compared to BPL (>1 cm lesion = 0.85 and ≤1 cm lesion = 0.81). Among the 4 readers, average intraobserver visual DS agreement between OSEM and BPL was 0.67 for lesions >1cm and 0.4 for lesions ≤1 cm. F-18 Fluorodeoxyglucose PET/CT of diffuse large B-cell lymphoma reconstructed with BPL has higher SUV values, altered DSs and reader agreement when compared to OSEM. This report finds volumetric PET measurements such as metabolic tumor volume to be similar between BPL and OSEM PET reconstructions. Efforts such as adoption of European Association Research Ltd accreditation should be made to harmonize PET data with an aim at balancing the need for harmonization and sensitivity for lesion detection.

Safety and Efficacy of CT-Guided Percutaneous Biopsy of Suspicious Subcentimeter Pelvic and Retroperitoneal Lymph Nodes Detected by 11C-Choline PET in Patients With Prostate Cancer.

BACKGROUND. In patients with prostate cancer, PET using targeted radiotracers can identify increased activity in small morphologically normal lymph nodes, facilitating earlier detection of metastatic disease. OBJECTIVE. The purpose of this article was to assess the efficacy and safety of CT-guided biopsy of suspicious pelvic and retroperitoneal lymph nodes measuring smaller than 1 cm detected by 11C-choline PET in patients with prostate cancer, with comparison with nodes measuring 1 cm or larger. METHODS. This retrospective study included patients with prostate cancer who underwent CT-guided percutaneous biopsy of suspicious pelvic or retroperitoneal lymph nodes detected by 11C-choline PET/CT or PET/MRI (performed because of a rising or elevated PSA level or known recurrent or metastatic disease) between June 1, 2012, and March 20, 2020. Patient, lymph node, and procedural characteristics, as well as biopsy outcomes and complications, were recorded. Biopsies of lymph nodes measuring smaller than 1 cm and of lymph nodes measuring 1 cm and larger were compared. RESULTS. A total of 269 patients (mean age, 68.7 ± 6.8 [SD] years) were included. A total of 156 patients underwent biopsy of lymph nodes measuring smaller than 1 cm (range, 3-9 mm); 113 patients underwent biopsy of lymph nodes measuring 1 cm or larger (range, 10-35 mm). Lymph nodes smaller than 1 cm and lymph nodes 1 cm and larger showed no significant difference in diagnostic yield (89.7% vs 92.9%; p = .40). Diagnostic yield was not significantly different between nodes smaller than 1 cm and nodes 1 cm and larger for any individual anatomic location within the pelvis or retroperitoneum (all p > .05). Malignant yield was lower for nodes smaller than 1 cm than for nodes 1 cm and larger (44.9% vs 63.7%; p = .003). The single biopsied 3-mm node had a nondiagnostic specimen. Diagnostic yield and malignant yield were 100.0% and 40.0%, respectively, for 4-mm nodes, and 95.5% and 45.5%, respectively, for 5-mm nodes. Patients with nodes smaller than 1 cm and nodes 1 cm and larger showed no significant difference in minor (12.8% vs 7.1%; p = .16) or major (0.6% vs 2.7%; p = .31) complication rate. CONCLUSION. The findings support the safety and efficacy of CT-guided biopsy of suspicious subcentimeter pelvic and retroperitoneal lymph nodes detected on 11C-choline PET in patients with prostate cancer. CLINICAL IMPACT. Earlier diagnosis of metastatic lymphadenopathy will impact prognostic assessment and management decisions in patients with recurrent prostate cancer.

Atypical Metastases in the Abdomen and Pelvis From Biochemically Recurrent Prostate Cancer: 11C-Choline PET/CT With Multimodality Correlation.

PET with targeted radiotracers has become integral to mapping the location and burden of recurrent disease in patients with biochemical recurrence (BCR) of prostate cancer (PCa). PET with 11C-choline is part of the National Comprehensive Cancer Network and European Association of Urology guidelines for evaluation of BCR. With advances in PET technology, increasing use of targeted radiotracers, and improved survival of patients with BCR because of novel therapeutics, atypical sites of metastases are being increasingly encountered, challenging the conventional view that prostate cancer rarely metastasizes beyond bones or lymph nodes. The purpose of this article is to describe such atypical metastases in the abdomen and pelvis on 11C-choline PET (including metastases to the liver, pancreas, genital tract, urinary tract, peritoneum, abdominal wall, and perineural spread) and to present multimodality imaging features and relevant imaging pitfalls. Given atypical metastases' inconsistent relationship with the serum PSA level and the nonspecific presenting symptoms, atypical metastases are often first detected on imaging. Awareness of their imaging features is important because their detection affects clinical management, patient counseling, prognosis, and clinical trial eligibility. Such awareness is particularly critical because the role of radiologists in the imaging and management of BCR will continue to increase given the expanding regulatory approvals of other targeted and theranostic radiotracers.

Phase II Evaluation of Stereotactic Ablative Radiotherapy (SABR) and Immunity in 11C-Choline-PET/CT-Identified Oligometastatic Castration-Resistant Prostate Cancer.

PURPOSE: Outcomes for resistant metastatic castration-resistant prostate cancer (CRPC) are poor. Stereotactic ablative radiotherapy (SABR) induces antitumor immunity in clinical and preclinical studies, but immunologic biomarkers are lacking. PATIENTS AND METHODS: Eighty-nine patients with oligometastatic CRPC were identified by 11C-Choline-PET (Choline-PET) from August 2016 to December 2019 and treated with SABR. Prespecified coprimary endpoints were 2-year overall survival (OS) and PSA progression. Secondary endpoints included 2-year SABR-treated local failure and 6-month adverse events. Correlative studies included peripheral blood T-cell subpopulations before and after SABR. RESULTS: 128 lesions in 89 patients were included in this analysis. Median OS was 29.3 months, and 1- and 2-year OS were 96% and 80%, respectively. PSA PFS was 40% at 1 year and 21% at 2 years. Local PFS was 84.4% and 75.3% at 1 and 2 years, respectively, and no grade ≥3 AEs were observed. Baseline high levels of tumor-reactive T cells (TTR; CD8+CD11ahigh) predicted superior local, PSA, and distant PFS. Baseline high levels of effector memory T cells (TEM; CCR7-CD45RA-) were associated with improved PSA PFS. An increase in TTR at day 14 from baseline was associated with superior OS. CONCLUSIONS: This is the first comprehensive effector T-cell immunophenotype analysis in a phase II trial before and after SABR in CRPC. Results are favorable and support the incorporation of immune-based markers in the design of future randomized trials in patients with oligometastatic CRPC treated with SABR.

Repeat Sentinel Lymph Node Surgery in Recurrent Breast Cancer: Peritumoral vs. Periareolar Injections.

BACKGROUND: In the setting of recurrent cancer, there is no standard methodology regarding the technical aspects of repeat sentinel lymph node (rSLN) surgery. We analyzed our institutional experience with attempted rSLN surgery to determine the optimal injection technique. MATERIALS AND METHODS: Single site, retrospective review of patients with prior lumpectomy for breast cancer who presented with recurrent or new ipsilateral breast cancer and underwent attempt at rSLN surgery from 2008 to 2017. Patients with prior mastectomy or no prior ipsilateral axillary operation were excluded. RESULTS: A total of 141 patients were included; 103 (73%) underwent successful rSLN biopsy procedure. Lymphoscintigraphy showed aberrant drainage in 32 (26%). Periareolar (PA) injection resulted in failed mapping in 23/99 (23%) and aberrant drainage in 25/85 (29%). By comparison, peritumoral (PT) injection had a 14/38 (37%) incidence of failed mapping and 7/37 (19%) aberrant drainage (P = .11 and .23, respectively). Of the patients with successful sentinel lymph node (SLN) biopsy procedure via PA injection, 11/76 (14%) were positive for metastatic disease as compared with 2/24 (8%) in PT injection. Sixteen patients had lymph node metastases; 13 (81%) were SLNs, including 3 positive aberrant SLNs. Five-year regional recurrence rates were 11.4% (95% confidence interval, 0%-21.5%) and 0% for PA and PT injection techniques, respectively. CONCLUSION: PA and PT injections had a similar incidence of SLN identification and aberrant drainage. Preoperative lymphoscintigraphy is beneficial in patients with recurrent breast cancer given the higher incidence of aberrant drainage in this population. Patients who underwent PA injections had a higher incidence of regional recurrences but this difference was not statistically significant.

FDG PET/CT and MRI Features of Pathologically Proven Schwannomas.

PURPOSE: The aim of this study was to examine the MRI and FDG PET/CT imaging features of pathologically proven schwannomas. PATIENTS AND METHODS: This institutional review board-approved retrospective study examined biopsy-proven schwannomas that underwent FDG PET/CT and/or MRI at our institution between January 1, 2002, and April 1, 2018. PET/CT features analyzed included SUVmax, metabolic ratios, volumetric metabolic measures, presence of calcification, and pattern of FDG activity. MRI features included T1/T2 signal, enhancement pattern, margins, perilesional edema, presence of muscular denervation, and size. RESULTS: Ninety-five biopsy-proven schwannomas were identified (40 with both PET and MRI, 35 with PET only, and 20 with MRI only), 46 females and 49 males, average age of 57.7 ± 15.3 years. The average largest dimension was 4.6 ± 2.7 cm, the average SUVmax was 5.4 ± 2.7, and lesion SUVmax/liver SUVmean was 2.2 ± 1.2. Eleven (15%) of 75 lesions had SUVmax greater than 8.1, 26/75 (35%) had SUVmax greater than 6.1, and 14/75 (19%) had lesion SUVmax/liver SUVmean greater than 3.0. On MRI, 29/53 (55%) demonstrated internal nonenhancing areas. Twenty-eight (70%) of 40 lesions with both MRI and PET demonstrated at least 1 imaging feature concerning for malignant peripheral nerve sheath tumor (irregular margins, internal nonenhancement, perilesional edema, heterogeneous FDG uptake, or SUVmax >8.1). Lesions with heterogeneous FDG activity had higher SUVmax (6.5 ± 0.5 vs 4.7 ± 0.4, P = 0.0031) and more frequent internal nonenhancement on MRI (P = 0.0218). CONCLUSIONS: Schwannomas may be large, be intensely FDG avid, and demonstrate significant heterogeneity, features typically associated with malignant peripheral nerve sheath tumors. A significant proportion exhibit FDG activity above cutoff levels previously thought useful in differentiating malignant from benign peripheral nerve sheath tumors.

11C-choline positron emission tomography/computed tomography for detection of disease relapse in patients with history of biochemically recurrent prostate cancer and prostate-specific antigen ≤0.1 ng/ml.

OBJECTIVES: The objective was to evaluate the diagnostic performance of surveillance11 C-choline positron emission tomography/computed tomography (PET/CT) for the detection of disease relapse in patients with a history of biochemically recurrent (BCR) prostate cancer (PCa) and prostate-specific antigen (PSA) ≤0.1 ng/ml. MATERIALS AND METHODS: We included patients who had been treated for BCR PCa and had a surveillance11 C-choline PET/CT at serum PSA ≤0.1 ng/ml. Positive surveillance PET/CT was defined as a study that identified a new tracer-avid lesion or new tracer uptake in a previously treated lesion or both. Findings were confirmed against a composite radiologic-pathologic gold standard. Time to recurrence association analyses were performed for disease relapse risk with the use of Cox proportional hazards regression. RESULTS: In total, 13 (12.1%) of the 107 patients had positive surveillance PET/CT scans, confirmed on pathologic assessment (n = 5) and subsequent imaging (n = 8). Among these 13 patients, ten had distant metastases, two had local recurrence, and one had both. Nine of the ten patients with metastases had oligometastatic disease defined as the presence of ≤3 metastases. Serum PSA became detectable again in only seven patients with positive surveillance PET/CT, after a mean interval from surveillance PET/CT of 292 days (range: 105-543 days). We identified an association of N stage with increased risk of recurrence (hazard ratio = 3.85; P = 0.036) although this was not significant after accounting for multiple testing. CONCLUSIONS: Surveillance11 C-choline PET/CT can detect early disease relapse at serum PSA ≤0.1 ng/ml in patients with a history of BCR PCa.

Percutaneous Image-Guided Nodal Biopsy After 11C-Choline PET/CT for Biochemically Recurrent Prostate Cancer: Imaging Predictors of Disease and Clinical Implications.

PURPOSE: Management of recurrent prostate cancer necessitates timely diagnosis and accurate localization of the sites of recurrent disease. The purpose of this study was to assess predictors of histologic outcomes after 11C-choline positron emission tomography/computed tomography (CholPET) to increase the positive predictive value and specificity of CholPET in identifying imaging predictors of malignant and benign nodal disease to better inform clinical decision making regarding local therapy planning. MATERIALS AND METHODS: Retrospective review of patients undergoing CholPET followed by percutaneous core needle biopsy between January 1, 2010 and January 1, 2016. A total of 153 patients were identified who underwent 166 biopsy procedures. Patient, CholPET, procedural, and pathologic characteristics were recorded. RESULTS: A total of 157 biopsies were technically successful, and 110 (70.1%; 95% confidence interval, 62.2-77.1) yielded histologic results abnormal for metastatic prostate cancer. Lesion location, lesion maximum standardized uptake value (SUVmax), SUV ratio (calculated as the ratio of SUVmax to SUV mean in the right atrium), prostate-specific antigen, lesion short axis length, total Gleason score, and castration resistance were all associated with abnormal biopsy results (P values <.001, <.001, <.001, .02, .02, .02, and .015, respectively). External iliac, common iliac, and inguinal sites were associated with much lower rates of histologic positivity (mean [95% confidence interval], 51.2% [35.1-67.1], 46.2% [19.2-74.9], and 33.3% [7.5-70.1]), respectively. CONCLUSIONS: In a cohort of patients in whom core needle biopsy was performed after CholPET, characteristics of choline localization including node location, SUVmax, lesion-to-blood pool SUV ratio, prostate-specific antigen, total Gleason score, and castration resistance were significantly associated with abnormal biopsy results for metastatic disease on CholPET. Relatively high false positive rates were found in common iliac, external iliac, and inguinal lymph node locations. Histologic confirmation of these sites should be strongly considered in the appropriate clinical scenario before designing additional local therapy plans.

Multimodal Imaging Aids in the Diagnosis of Perineural Spread of Prostate Cancer.

BACKGROUND: The perineural spread of prostate cancer into pelvic peripheral nerves is a rare, but increasingly recognized, entity. This form of metastasis invades the lumbosacral plexus via the splanchnic nerves innervating the prostate. The prevalence of perineural spread is likely underappreciated, and further imaging-based studies are needed to elucidate its true frequency. METHODS: A retrospective review was performed using an institutional radiology database. Medical reports from patients with prostate cancer who had undergone positron emission tomography (PET) imaging were queried for terms suggestive of perineural spread. PET and magnetic resonance imaging (MRI) from the identified patients were blindly reviewed for peripheral nerve involvement by 2 nuclear medicine and 2 musculoskeletal radiologists. RESULTS: A total of 22 patients were identified. After review by the radiologists, 16 patients had positive findings of perineural spread found on PET and 15 had abnormalities found on MRI involving lumbosacral plexus neural elements. All patients with biopsy-proven neoplastic perineural spread (including 1 patient with malignant peripheral nerve sheath tumor) had positive findings on both PET and MRI. All patients with biopsy-proven inflammatory lesions had negative PET and variable MRI findings. CONCLUSIONS: The perineural spread of prostate cancer might be more common than previously thought. The use of multimodal imaging for patients suspected of having perineural spread should be a part of the treatment algorithm. Targeted fascicular biopsy might be indicated for patients with progressive neurological deficit and an unclear diagnosis.

Diagnostic performance of unenhanced computed tomography and 18 F-fluorodeoxyglucose positron emission tomography in indeterminate adrenal tumours.

OBJECTIVE: Evidence on the diagnostic performance of adrenal imaging is limited. We aimed to assess the diagnostic performance of unenhanced computed tomography (CT) and 18 F-fluorodeoxyglucose (18 FDG) positron emission tomography (PET)/CT imaging in a high-risk population for adrenal malignancy using an optimal reference standard. DESIGN: Retrospective cohort study. METHODS: Imaging studies of patients with adrenal nodules who underwent adrenal biopsy and/or adrenalectomy between 1994 and 2014 were reviewed and compared to the reference standard of histology. Eighty % of patients presented with known or suspected extra-adrenal malignancy. RESULTS: Unenhanced abdominal CT was performed in 353 patients with adrenal lesions; median size was 3 (0.7-15) cm and median radiodensity was 33 (-21-78) Hounsfield units (HU). Radiodensity of >10 HU diagnosed malignancy with a sensitivity of 100%, specificity of 33%, positive predictive value (PPV) of 72% and negative predictive value (NPV) of 100%. 18 FDG-PET/CT was performed in 89 patients; median tumour size was 2.1 (0.7-9.2) cm. Maximum standardized uptake (SUV max) was higher in malignant lesions when compared to benign lesions (median=10 [2.3-29.4] vs 3.7 [1.4-24.5], respectively, P<.0001). Similarly, median SUV max lesion to SUV max liver ratio (ALR) in malignant lesions was higher than in benign lesions (median=3 [0.74-13.4] vs 1.2 [0.5-6.6], respectively, P<.0001). 18 FDG-PET/CT ALR >1.8 diagnosed malignancy with a sensitivity of 87%, specificity of 84%, PPV of 85% and NPV of 86%. CONCLUSION: Noncontract CT radiodensity of ≤10 HU excludes malignancy even in a high-risk population. For indeterminate adrenal lesions, given a superior specificity, 18 FDG-PET/CT could be considered as a second stage imaging study.

Pittsburgh compound B (PiB) PET imaging of meningioma and other intracranial tumors.

Meningiomas are the most common intracranial tumors. Diagnosis by MRI is generally straightforward, but lack of imaging specificity can present a diagnostic dilemma, particularly in patients with cancer. We report our experience with meningioma identification on Pittsburgh compound B (PiB) PET/CT. Patients who underwent PiB PET/CT from 2006 to 2015 were reviewed to identify those with intracranial tumors. Tumor types were classified by MR appearance, or by pathology when available. Maximum standardized uptake value (SUVmax) measurements of tumor PiB activity were compared across tumor types. 2472 patients underwent PiB PET/CT in the period of interest; 45 patients (1.8%) had probable or definite intracranial tumor. Tumor types were meningioma (29/45, 64%), vestibular schwannoma (7/45, 16%), pituitary macroadenoma (4/45, 9%), metastatic disease (2/45, 4%), and others (3/45, 7%). In patients with meningioma, the mean lesion SUVmax was 2.05 (SD 1.37), versus 1.00 (SD 0.42) in patients with non-meningioma tumors (p < 0.01). A receiver operating curve was created for lesion:cerebellum SUVmax ratio, with an area under the curve of 0.91 for a value of 1.68. At or above this ratio, specificity for meningioma was 100% (95% CI 79-100%) and sensitivity was 76% (95% CI 57-90%). PiB PET activity within an intracranial tumor is a highly specific and reasonably sensitive marker of meningioma. Further prospective evaluation is warranted to validate this result as well as to assess the performance of commercially available beta-amyloid radiotracers in meningioma identification.

Patterns of Recurrence After Postprostatectomy Fossa Radiation Therapy Identified by C-11 Choline Positron Emission Tomography/Computed Tomography.

PURPOSE: To evaluate C-11 choline positron emission tomography/computed tomography (CholPET) in staging and determining patterns of recurrence in prostate cancer patients with rising prostate-specific antigen levels after prostatectomy radiation therapy (RT). METHODS AND MATERIALS: The study includes patients with biochemical failure after postprostatectomy RT who underwent CholPET between 2008 and 2015. Patient and disease characteristics were examined in relation to sites of recurrence. All RT dosimetry records were reviewed, and recurrences were mapped on a representative computed tomography dataset with their relationship relative to the irradiated fossa field as out of field (OOF), edge of field (EOF; recurrence within <45-Gy isodose lines), or in field (IF; recurrence within ≥45-Gy isodose lines). RESULTS: Forty-one patients were identified with 121 sites of recurrence (median 2 sites; interquartile range [IQR], 1-4). The median prostate-specific antigen level at CholPET was 3.1 (IQR, 1.9-5.6) ng/mL. Median interval from RT to biochemical failure was 24 (IQR, 10-46) months, with recurrence identified on CholPET at a median of 15 (IQR, 7-28) months from biochemical failure. Histologic confirmation of recurrence was obtained in 20 patients (49%), with the remainder confirmed by treatment response. Five patients (12%) had IF recurrences, 10 patients (24%) had EOF recurrences (median dose 10 Gy; IQR, 5-30 Gy), and 36 patients (88%) had OOF recurrences. Ten patients had combination failures: 6 (15%) EOF/OOF and 4 (10%) IF/OOF. Fifty-seven recurrences (47%) were pelvic nodal sites inferior to the L5-S1 interspace, of which 52 (43%) were within a pelvic RT field. Eighty-one recurrences (67%) were nodal and inferior to the aortic bifurcation. CONCLUSIONS: Using CholPET, we found that the majority of patients evaluated for biochemical failure recurred outside of the postprostatectomy RT field. Furthermore, most recurrence sites were nodal and inferior to the aortic bifurcation. These results provide data that may be useful for examining strategies that include elective lymph node irradiation in postprostatectomy patients.

Identification of Site-specific Recurrence Following Primary Radiation Therapy for Prostate Cancer Using C-11 Choline Positron Emission Tomography/Computed Tomography: A Nomogram for Predicting Extrapelvic Disease.

BACKGROUND: Management of recurrent prostate cancer (CaP) after radiotherapy (RT) is dependent on accurate localization of the site of recurrent disease. OBJECTIVE: To describe the anatomic patterns and clinical features associated with CaP recurrence following RT identified on advanced imaging. DESIGN, SETTING, AND PARTICIPANTS: Retrospective review of 184 patients with a rising prostate-specific antigen (PSA) after RT for CaP. INTERVENTION: C-11 choline positron emission tomography/computed tomography (CholPET). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Recurrence patterns were classified as pelvic soft tissue only (as a surrogate for potentially salvageable disease) versus any extrapelvic disease, and clinical features were compared between patterns. Multivariable logistic regression was used to generate a predictive nomogram for extrapelvic recurrence. Discrimination was assessed with a c-index. RESULTS AND LIMITATIONS: Recurrence site was identified in 161 (87%) patients, with 95 (59%) sites histologically confirmed. Factors associated with the detection of recurrence included the difference between PSA nadir and PSA at CholPET (odds ratio: 1.30, p<0.01) and National Comprehensive Cancer Network high-risk classification (odds ratio: 10.83, p=0.03). One hundred (54.3%) patients recurred in the pelvic soft tissue only, while 61 (33%) had extrapelvic recurrence. Of 21 patients who underwent CholPET prior to meeting the Phoenix criteria of biochemical failure, 15 (71%) had recurrence identified on CholPET with 11 localized to the pelvis. On multivariable analysis, the difference between PSA nadir and PSA at CholPET, time from RT, and National Comprehensive Cancer Network risk group were predictive of recurrence outside of the pelvis, and a nomogram was generated with a c-index of 0.79. CONCLUSIONS: CholPET identified the site of recurrence in 87% of patients with a rising PSA after RT; most commonly within the pelvis in potentially salvageable locations. A predictive nomogram was generated, and pending external validation, this may aid in assessing the risk of disease beyond the pelvis. These findings underscore the importance of advanced imaging when considering management strategies for patients with a rising PSA following primary RT. PATIENT SUMMARY: We identified anatomic patterns of recurrence in patients with a rising prostate-specific antigen after radiotherapy using C-11 choline positron emission tomography/computed tomography. Most recurrences were localized to the pelvis and we were able to generate a tool to aid in disease localization prior to evaluation with advanced imaging.

Utility of 18F-FDG PET for Predicting Histopathologic Response in Esophageal Carcinoma following Chemoradiation.

INTRODUCTION: For patients with esophageal cancer undergoing neoadjuvant chemoradiation (CRT) followed by surgical resection, complete histopathologic response (pCR) is associated with favorable overall survival (OS). The aim of this study was to evaluate the correlation between 18F-fluorodeoxyglucose positron emission tomography (FDG PET) response to neoadjuvant CRT and pCR. METHODS: Maximum standardized uptake values and standardized uptake ratios (SURs) were measured before and after CRT. SUR was normalized to liver uptake and mediastinal blood pool uptake. FDG PET complete response was defined as metabolic activity normalization to hepatic and blood pool activity. The correlation between FDG PET parameters and pCR was examined through logistic regression analyses. RESULTS: In total, 193 patients were monitored for a median of 3.6 years after initiation of CRT. Most tumors were adenocarcinoma (85%) and stage T3 (75%). Complete FDG PET response and pCR occurred in 27% and 34% of patients, respectively. Histologic findings, chemotherapy type, tumor stage, and radiation dose were not significantly associated with complete radiographic response. The rates of pCR in patients with and without radiographic complete response were 42% and 31% (p = 0.17), respectively. No predictive correlation was found between pCR and change in maximum standardized uptake value (p = 0.25), in SUR normalized to blood pool uptake (p = 0.20), or in SUR normalized to liver uptake (p = 0.15). The 5-year OS rate was 46% for patients with a complete FDG PET response versus 44% without a complete response (p = 0.78). The 5-year OS rate of patients who achieved pCR was 49% versus 43% for patients with residual tumor (p = 0.04). CONCLUSION: For patients with esophageal cancer who received neoadjuvant chemoradiation, pretreatment and posttreatment FDG PET parameters did not correlate with pCR or OS.

Procedural and clinical outcomes of percutaneous adrenal biopsy in a high-risk population for adrenal malignancy.

OBJECTIVE: The role of percutaneous adrenal biopsy in a high-risk population for adrenal malignancy has not been fully investigated. Our aim was to describe the clinical presentation leading to the adrenal biopsy and evaluate the diagnostic performance, complications and non diagnostic rate of adrenal biopsy. DESIGN: Single-centre, retrospective cohort study. PATIENTS AND MEASUREMENTS: Medical records of patients who underwent adrenal biopsy between 1994 and 2014 were reviewed. Adrenal biopsy outcome was compared to a predefined reference standard. RESULTS: Biopsy was performed in 418 patients [62% men, median age 69 years (range, 15-91)] on 419 adrenal lesions, median size 3·1 cm (range, 0·6-24). The main indication for adrenal mass biopsy was (349/419, 83%) suspected adrenal metastasis from a known or suspected extra-adrenal primary source. Only 116 of 419, 28% of cases had prebiopsy biochemical testing for pheochromocytoma. Biopsy-related complications occurred in 4% of the patients. Histology revealed a metastasis in 231 of 419 (55%), benign adrenal tissue in 137 of 419 (33%), adrenocortical carcinoma in eight of 419 (2%), other lesions in 23 of 419 (5%) including seven cases of pheochromocytoma and six cases of infectious process. Biopsy was nondiagnostic in 20 of 419 (5%). All adrenal masses with unenhanced radiodensity ≤10 HU (42/137, 31%) proved to be benign adrenal adenomas. Adrenal biopsy diagnosed malignancy with a sensitivity of 88·5%, specificity of 91·5%, positive predictive value of 93·4% and negative predictive value of 85·5%. CONCLUSION: When used in the appropriate clinical setting, adrenal biopsy is a powerful tool in the diagnostic algorithm of the evaluation of adrenal masses with features suspicious for malignancy. Efforts to increase awareness to perform biochemical testing for pheochromocytoma prior to adrenal biopsy are needed.

Comparison of facet joint activity on 99mTc-MDP SPECT/CT with facet joint signal change on MRI with fat suppression.

PURPOSE: We compared signal change on magnetic resonance imaging (MRI) with fat suppression and bone scan activity of lumbar facet joints to determine if these two imaging findings are correlated. METHODS: We retrospectively identified all patients who underwent imaging of the lumbar spine for pain evaluation using both technetium-99m methylene disphosphonate single-photon emission computed tomography/computed tomography (99mTc-MDP SPECT/CT) and MRI with at least one fat-suppressed T2- or T1-weighted sequence with gadolinium enhancement within a 180-day interval, at our institution between 1 January 2008 and 19 February 2013. Facet joint activity on 99mTc-MDP SPECT/CT and peri-facet signal change on MRI were rated as normal or increased. Agreement between the two examination types were determined with the κ and prevalence-adjusted bias-adjusted κ (PABAK) statistics. RESULTS: This study included 60 patients (28 male, 47%), with a mean age of 49±19.7 years (range, 12-93 years). The κ value indicated no agreement between 99mTc-MDP SPECT/CT and MRI (κ=-0.026; 95% confidence interval: -0.051, 0.000). The PABAK values were fair to high at each spinal level, which suggests that relatively low disease prevalence lowered the κ values. Together, the κ and PABAK values indicate that there is some degree of intermodality agreement, but that it is not consistent. CONCLUSION: Overall, facet joint signal change on fat-suppressed MRI did not always correlate with increased 99mTc-MDP SPECT/CT activity. MRI and 99mTc-MDP SPECT/CT for facet joint evaluation should not be considered interchangeable examinations in clinical practice or research.

Evaluation of (18)F-FDG PET and MRI in differentiating benign and malignant peripheral nerve sheath tumors.

OBJECTIVE: To compare 18F-FDG PET/CT and MRI for differentiating benign and malignant peripheral nerve sheath tumors (BPNSTs and MPNSTs) and correlate imaging characteristics with histopathology. MATERIALS AND METHODS: Patients with pathologically proven PNSTs undergoing 18F-FDG PET/CT were retrospectively reviewed. PET/CTs and, if available, MRIs were analyzed, noting multiple imaging characteristics and likely pathology (benign or malignant). RESULTS: Thirty-eight patients with 23 BPNSTs and 20 MPNSTs were analyzed. MPNSTs had higher SUVmax (10.1 ± 1.0, 4.2 ± 0.4, p < 0.0001), metabolic tumor volume (146.5 ± 39.4, 21.7 ± 6.6 cm(3), p = 0.01), total lesion glycolysis (640.7 ± 177.5, 89.9 ± 23.2 cm(3)*g/ml, p = 0.01), and SUVmax/LiverSUVmean (5.3 ± 0.5, 2.0 ± 0.2, p < 0.0001). All lesions with SUVmax < 4.3 were benign. All lesions with SUVmax > 8.1 were malignant. SUVmax cutoff of 6.1 yielded 90.0 % sensitivity and 78.3 % specificity for MPNSTs. SUVmax/LiverSUVmean cutoff of 3.0 yielded 90.0 % sensitivity and 82.6 % specificity. MPNSTs more commonly had heterogeneous FDG activity (p < 0.0001), perilesional edema (p = 0.004), cystic degeneration/necrosis (p = 0.015), and irregular margins (p = 0.004). There was no difference in lesion size, MRI signal characteristics, or enhancement. Expertly interpreted MRI had 62.5-81.3 % sensitivity and 94.1-100.0 % specificity while PET had 90.0-100.0 % sensitivity and 52.2-82.6 % specificity for diagnosing MPNSTs. CONCLUSIONS: FDG PET and MRI play a complementary role in PNST evaluation. Multiple metabolic parameters and MRI imaging characteristics are useful in differentiating BPNSTs from MPNSTs. This underscores the potential critical role of PET/MRI in these patients.

BRAF Inhibitor-Induced Panniculitis: Appearance on 18F-FDG PET/CT.

BRAF inhibitors vemurafenib and dabrafenib have become the standard of care for treatment of stage IV metastatic melanoma harboring a BRAF mutation. Panniculitis is a rare but known adverse side effect of these agents and presents with tender erythematous nodules. These nodules may demonstrate uptake on F-FDG PET/CT, which may mimic metastatic disease in patients undergoing treatment. We present a case of BRAF inhibitor-induced panniculitis in a patient with stage IV metastatic melanoma and discuss the imaging findings on F-FDG PET/CT.