CT "halo sign" in pulmonary tuberculoma.

The CT halo sign has been described as the CT finding of a low-attenuation zone surrounding a pulmonary nodule. It is an early clue to the diagnosis of invasive pulmonary aspergillosis. We describe a case of CT halo sign associated with a pulmonary tuberculoma. Therefore, we think that a diagnosis other than invasive pulmonary aspergillosis should be considered in the presence of the CT halo sign in immunocompetent patients.     

CT morphological features of the reversed halo sign in pulmonary paracoccidioidomycosis

Objective:

The purpose of this study was to identify morphological characteristics of the reversed halo sign (RHS) on chest CT in patients with pulmonary paracoccidioidomycosis (PCM) that may aid the diagnosis of this fungal disease.

Methods:

We retrospectively reviewed chest CT images from 23 patients with proven pulmonary PCM who demonstrated the RHS. Two chest radiologists analysed the morphological characteristics of the lesions and reached decisions by consensus.

Results:

We identified 64 RHSs on CT images from the 23 patients. Multiple lesions were observed in all cases, with middle and lower lung zone predominance occurring in 17 patients (73.9% of cases). 34 (53.1%) RHSs were round and 30 (46.9%) were oval. Outer borders of the RHSs were smooth in 32 (50%) lesions, nodular in 16 (25%) lesions and irregular/spiculated in 16 (25%) lesions. Ground-glass opacity was observed inside 63 (98.4%) lesions.

Conclusion:

Our data suggest that morphological characteristics of the RHS on chest CT, such as the presence of multiple lesions, middle and lower lung zone predominance and a spiculated RHS ring, as well as the association with other parenchymal patterns, should lead radiologists to include PCM in the differential diagnosis of PCM in endemic areas.

Advances in knowledge:

This is the largest series of patients with RHS due to PCM and is also the first study to report RHS lesions with spiculated or irregular walls. The study adds information regarding morphological characteristics of the RHS that may raise suspicion of PCM on chest CT, particularly in endemic areas of the disease.     

The CT halo: a new sign in active pulmonary sarcoidosis

A case of pulmonary sarcoidosis is presented characterized by multiple coalescent nodules and peripheral ground glass halos, which were fully reversible under repeat systemic glucocorticoid treatment. The differential diagnostic aspects of the pulmonary CT halo sign and its potential for indicating active reversible disease in patients with sarcoidosis is discussed.     

The reversed halo sign on high-resolution CT in infectious and noninfectious pulmonary diseases

OBJECTIVE: The purpose of this article is to describe diseases that may present with the reversed halo sign on high-resolution CT. We emphasize the tomographic features most frequently associated with this sign and correlate them with histologic findings. CONCLUSION: A wide spectrum of infectious and noninfectious diseases may present with the reversed halo sign on chest CT. The nonspecific nature of this sign should not cloud an otherwise fairly straightforward diagnosis, especially when associated background findings are typical. Although a rigorous analysis of associated CT findings may help with the differential diagnosis, histologic assessment is often needed for a definitive determination of the cause.     

Assessing response to therapy of spinal metastases with gadolinium-enhanced MR imaging.

The utility of gadolinium-enhanced magnetic resonance (MR) imaging in assessing the response of spinal metastases to therapy was evaluated. Fifteen patients (62 affected vertebral bodies) with spinal metastases were evaluated with gadopentetate dimeglumine-enhanced imaging before and after irradiation or chemotherapy. Signal intensities of the lesions and of adjacent normal vertebral bodies were compared. Before therapy, metastatic foci enhanced significantly more than did normal vertebral bodies. After therapy, the lesions were divided into 37 responding lesions (group 1) and 25 nonresponding lesions (group 2). In group 1, lesion enhancement diminished considerably and the patients with these lesions remained clinically asymptomatic for 2-6 months. In group 2, lesion enhancement did not diminish much, and the difference between the groups was significant. Gadolinium-enhanced MR imaging may thus be a useful method for assessing the effectiveness of therapy for spinal metastases.     

Sonographic target sign and rim enhancement on magnetic resonance imaging in metastatic melanoma to the breast

We report a target sign on ultrasound and peripheral rim enhancement on gadolinium (Gd)-enhanced MRI images in metastasis to the breast from melanoma. These classic signs, as reported in the liver (ultrasound target sign) and in primary breast cancers (Gd rim enhancement), are probably also of value in cases of metastatic lesions to the breast.     

Reversed halo sign on thin-section CT in a patient with non-specific interstitial pneumonia

We present a case of non-specific interstitial pneumonia (NSIP) with reversed halo sign on thin-section CT. A 52-year-old female presented with a cough and New York Heart Association (NYHA) class 2 dyspnoea of 4 months duration. A chest radiograph showed poorly defined, patchy ground-glass opacities in both lungs. Thin-section CT demonstrated the reversed halo sign, which is a central ground-glass opacity surrounded by crescent or ring-shaped areas of consolidation in multifocal areas. Multifocal patchy ground-glass opacity and consolidation and enlarged paratracheal, hilar and subcarinal lymph nodes were also shown. Video-assisted thoracic surgical (VATS) lung biopsy was performed, and histopathology revealed cellular NSIP.     

Target-shaped combined halo and reversed-halo sign,an atypical chest CT finding in COVID-19

Typical chest CT findings in COVID-19 have been described as bilateral peripheral ground glass opacities, with or without consolidation. Halo sign and reversed halo sign have been reported as atypical imaging findings in this disease. However, to the best of our knowledge, combined presence of these signs has never been reported before. Herein, we present a COVID-19 patient with numerous atypical target-shaped, combined halo and reversed halo pulmonary lesions, in the absence of any other underlying disease.     

CT evaluation for pulmonary metastases in patients with extrathoracic malignancy

Computed tomography (CT) is clearly more sensitive than chest radiography or conventional linear tomography in the detection of pulmonary metastases. Routine chest CT scans may reveal peripheral nodules as small as 2-3 mm, and high-resolution CT may demonstrate lymphangitic carcinomatosis. Specificity remains a problem, but attention to clinical factors, such as the type of extrathoracic malignancy (ETM), epidemiology, patient age, and prior treatment, should be of assistance. CT is useful in the evaluation of an apparent solitary pulmonary nodule or an equivocal radiographic finding. For single or multiple nodules, CT is essential for planning invasive procedures such as biopsy or surgical resection. Routine CT scanning to screen for occult metastases is indicated only for patients with ETMs that have a high propensity for metastasizing to the lungs and for which detection of pulmonary metastases would influence therapy--bone and soft-tissue sarcomas, most pediatric tumors, choriocarcinoma, nonseminomatous testicular carcinoma, and possibly advanced melanoma. Future large prospective studies evaluating individual malignancies are needed to assess the impact on long-term survival of early detection of pulmonary metastases with CT.     

Comparison of FDG-PET/CT and contrast-enhanced CT for monitoring therapy response in patients with metastatic breast cancer

Purpose

The aim of this study was to compare fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) and contrast-enhanced computed tomography (CE-CT) for the prediction of progression-free survival (PFS) and disease-specific survival (DSS) in patients with stage IV breast cancer undergoing systemic therapy.

Methods

Sixty-five patients with metastatic breast cancer treated with first- or second-line systemic therapy in prospective clinical trials were included. Response to treatment was evaluated by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 for CE-CT and by PET Response Criteria in Solid Tumors (PERCIST), respectively.

Results

All responders by RECIST (n = 22) were also responders by PERCIST, but 40% (17/43) of non-responders by RECIST were responders by PERCIST. Responses according to RECIST and PERCIST both correlated with PFS, but PERCIST showed a significantly higher predictive accuracy (concordance index for PFS: 0.70 vs. 0.60). One-year PFS for responders vs. non-responders by RECIST was 59% vs. 27%, compared to 63% vs. 0% by PERCIST. Four-year DSS of responders and non-responders by RECIST was 50% and 38%, respectively (p = 0.2, concordance index: 0.55) as compared to 58% vs. 18% for PERCIST (p < 0.001, concordance index: 0.65). Response on PET/CT was also a significantly better predictor for DSS than disease control on CE-CT.

Conclusions

In patients with metastatic breast cancer, tumor response on PET/CT appears to be a superior predictor of PFS and DSS than response on CE-CT. Monitoring tumor response by PET/CT may increase the power of clinical trials using tumor response as an endpoint, and may improve patient management in clinical routine.

     

以肌无力为首发症状的肺内结外NK/T细胞淋巴瘤PET/CT显像一例

笔者报道了一例以四肢乏力为首发症状入院的病例,分别从患者的临床症状、相关实验室检查、CT、18F-FDG及68Ga-1, 4, 7, 10-四氮杂十二烷-N, N, N, N-四乙酸-D-苯丙氨酸1-酪氨酸3-苏氨酸-8-奥曲肽PET/CT影像学诊断等方面分析了该病例的特点,并对原发性肺内结外NK/T细胞淋巴瘤的影像学诊断方法进行了文献回顾。由于该病发生率低,笔者意在提示影像医师在遇到类似病例时,应把握整体,避免先入为主的思维,从而提高诊断水平。     

Functional imaging as an aid to decision-making in metastatic paraganglioma

Malignant paraganglioma is a rare and slow growing tumour of neuroendocrine origin. At the time of diagnosis, the tumour is usually widespread, with limited therapeutic options. A variety of functional imaging studies are available for staging the disease, guiding therapy and monitoring treatment response. These include 123I-MIBG or 131I-MIBG, 111In-pentetreotide or 111In-lanreotide (somatostatin analogues), and 18F-FDG positron emission tomography. Various radionuclides, including 131I and 90Y, can be targeted to the tumour using MIBG or pentetreotide. Such targeted radionuclide therapy may provide valuable long-term palliation in such patients. We present two cases with metastatic paragangliomas who had widespread soft tissue and bone metastases. One patient was treatment naive and the second had received previous chemotherapy. The functional imaging work-up performed and the targeted radionuclide therapies considered in these patients are described. Both patients were treated with 131I-MIBG. Partial tumour response and complete symptomatic and hormonal response was achieved in one patient; in the second patient there was no change.     

99mTc- and 111In-labeled alpha-melanocyte-stimulating hormone peptides as imaging probes for primary and pulmonary metastatic melanoma detection.

It is highly desired to develop new imaging probes for early detection of melanoma as early diagnosis and prompt surgical removal are a patient's best hope for a cure. The purpose of this study was to determine whether (99m)Tc- and (111)In-labeled alpha-melanocyte-stimulating hormone (alpha-MSH) peptides could be used as imaging probes for primary and metastatic melanoma using dual-modality micro-SPECT/CT detection. METHODS: [Cys(3,4,10),d-Phe(7),Arg(11)]alpha-MSH(3-13) [(Arg(11))CCMSH] and [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]Re(Arg(11))CCMSH [DOTA-Re(Arg(11))CCMSH] were labeled with (99m)Tc and (111)In. The pharmacokinetics of (99m)Tc-(Arg(11))CCMSH were examined in B16/F1 flank and B16/F10 pulmonary metastatic murine melanoma-bearing C57 mice. The biodistribution of (111)In-DOTA-Re(Arg(11))CCMSH was performed in B16/F10 pulmonary metastatic murine melanoma-bearing C57 mice. SPECT/CT of (99m)Tc-(Arg(11))CCMSH and (111)In-DOTA-Re(Arg(11))CCMSH was determined in B16/F1 flank and B16/F10 pulmonary metastatic murine melanoma-bearing C57 mice. RESULTS: (99m)Tc-(Arg(11))CCMSH and (111)In-DOTA-Re(Arg(11))CCMSH exhibited high tumor uptakes (14.03 +/- 2.58 percentage injected dose/gram [%ID/g] at 1 h after injection and 17.29 +/- 2.49 %ID/g at 2 h after injection) in B16/F1 melanoma-bearing mice, and the flank melanoma tumors were clearly imaged by micro-SPECT/CT. Nontarget organ uptakes were considerably lower except for the kidneys. B16/F10 pulmonary melanoma metastases were also clearly visualized by micro-SPECT/CT using (99m)Tc-(Arg(11))CCMSH or (111)In-DOTA-Re(Arg(11))CCMSH as the imaging probe. (99m)Tc-(Arg(11))CCMSH exhibited images with greater resolution of metastatic melanoma lesions compared with (111)In-DOTA-Re(Arg(11))CCMSH. CONCLUSION: The favorable tumor imaging properties of (99m)Tc-(Arg(11))CCMSH and (111)In-DOTA-Re(Arg(11))CCMSH highlighted their potential as novel probes for primary and metastatic melanoma detection.     

Invasive pulmonary aspergillosis in acute leukemia: characteristic findings on CT, the CT halo sign, and the role of CT in early diagnosis

Invasive pulmonary aspergillosis (IPA) in immunocompromised patients is often difficult to diagnose. Many pathogens present initially with similar, nonspecific pulmonary findings. Air crescent formation has been reported to be highly suggestive of IPA in the appropriate clinical setting, but this is a late sign in an otherwise rapidly fatal infection. The authors reviewed the available chest computed tomography (CT) scans of nine patients with acute leukemia and documented IPA, including four patients with serial scans obtained during the course of infection. Typical CT findings of IPA were multiple inflammatory nodules, often with one large dominant mass, or a single peripheral masslike infiltrate. Cavitation or air crescent formation occurred late in the course of infection, usually at the time of bone marrow recovery from chemotherapy. CT scans obtained early in the course of infection in two patients demonstrated a distinctive feature of one or more pulmonary masslike infiltrates surrounded by a halo of low attenuation. These lesions subsequently progressed to cavitation or air crescent formation typical of IPA. While this CT halo sign may not be pathognomonic for Aspergillus, seen in the appropriate host, it may suggest early on the possibility of IPA.     

Imaging response to systemic therapy for bone metastases

In patients with osteotropic primary tumours such as breast and prostate cancer, imaging treatment response of bone metastases is essential for the clinical management. After treatment of skeletal metastases, morphological changes, in particular of bone structure, occur relatively late and are difficult to quantify using conventional X-rays, CT or MRI. Early treatment response in these lesions can be assessed from functional imaging techniques such as dynamic contrast-enhanced techniques by MRI or CT and by diffusion-weighted MRI, which are quantifiable. Among the techniques within nuclear medicine, PET offers the acquisition of quantifiable parameters for response evaluation. PET, therefore, especially in combination with CT and MRI using hybrid techniques, holds great promise for early and quantifiable assessment of treatment response in bone metastases. This review summarises the classification systems and the use of imaging techniques for evaluation of treatment response and suggests parameters for the early detection and quantification of response to systemic therapy.